| | 1 | CDECK ID>, INFORM. |
| | 2 | |
| | 3 | H E R W I G |
| | 4 | |
| | 5 | a Monte Carlo event generator for simulating |
| | 6 | +---------------------------------------------------+ |
| | 7 | | Hadron Emission Reactions With Interfering Gluons | |
| | 8 | +---------------------------------------------------+ |
| | 9 | G. Marchesini, Dipartimento di Fisica, Universita di Milano |
| | 10 | I.G. Knowles(*), M.H. Seymour(+) and B.R. Webber, |
| | 11 | Cavendish Laboratory, Cambridge |
| | 12 | ------------------------------------------------------------------------ |
| | 13 | with Deep Inelastic Scattering and Heavy Flavour Electroproduction by |
| | 14 | G.Abbiendi(@) and L.Stanco, Dipartimento di Fisica, Universita di Padova |
| | 15 | ------------------------------------------------------------------------ |
| | 16 | and Jet Photoproduction in Lepton-Hadron Collisions |
| | 17 | by J. Chyla, Institute of Physics, Prague |
| | 18 | ------------------------------------------------------------------------ |
| | 19 | (*)present address: Dept. of Physics & Astronomy, University of Glasgow |
| | 20 | ------------------------------------------------------------------------ |
| | 21 | (+)present address: Theory Division, CERN |
| | 22 | ------------------------------------------------------------------------ |
| | 23 | (@)present address: DESY, Hamburg |
| | 24 | ------------------------------------------------------------------------ |
| | 25 | Version 5.9 - 22nd July 1996 |
| | 26 | ------------------------------------------------------------------------ |
| | 27 | Main reference: |
| | 28 | G.Marchesini, B.R.Webber, G.Abbiendi, I.G.Knowles, M.H.Seymour, |
| | 29 | and L.Stanco, Computer Physics Communications 67 (1992) 465. |
| | 30 | ------------------------------------------------------------------------ |
| | 31 | Please send e-mail about this program to one of the authors at the |
| | 32 | following addresses: |
| | 33 | Decnet : 19616::webber, vxdesy::abbiendi, 19800::knowles |
| | 34 | Internet : webber@hep.phy.cam.ac.uk, knowles@v2.ph.gla.ac.uk, |
| | 35 | seymour@surya11.cern.ch, abbiendi@vxdesy.desy.de |
| | 36 | ------------------------------------------------------------------------ |
| | 37 | |
| | 38 | ****** CONTENTS ****** |
| | 39 | |
| | 40 | 1. INTRODUCTION |
| | 41 | 2. NEW FEATURES OF THIS VERSION |
| | 42 | 3. FEATURES NOT YET INCLUDED |
| | 43 | 4. PROGRAM STRUCTURE |
| | 44 | 5. BEAMS AND PROCESSES |
| | 45 | 6. INPUT PARAMETERS |
| | 46 | 7. COMMON BLOCK FILE |
| | 47 | 8. FORM FACTOR FILE |
| | 48 | 9. EVENT DATA |
| | 49 | 10. STATUS CODES |
| | 50 | 11. EVENT WEIGHTS |
| | 51 | 12. HEAVY FLAVOUR DECAYS |
| | 52 | 13. SPACE-TIME STRUCTURE OF EVENTS |
| | 53 | 14. COLOUR REARRANGEMENT MODEL |
| | 54 | 15. QCD HARD SUBPROCESSES |
| | 55 | 16. DIRECT PHOTON SUBPROCESSES |
| | 56 | 17. QCD HIGGS PLUS JET SUBPROCESSES |
| | 57 | 18. ELECTROWEAK SUBPROCESSES |
| | 58 | 19. INCLUDING NEW SUBPROCESSES |
| | 59 | 20. ERROR CONDITIONS |
| | 60 | 21. SAMPLE OUTPUT |
| | 61 | 22. GUIDE TO SAMPLE OUTPUT |
| | 62 | |
| | 63 | ------------------------------------------------------------------------ |
| | 64 | |
| | 65 | ****** 1. INTRODUCTION ****** |
| | 66 | |
| | 67 | HERWIG is a general-purpose event generator for high energy hadronic |
| | 68 | processes, with particular emphasis on the detailed simulation of |
| | 69 | QCD parton showers. The program has the following special features: |
| | 70 | |
| | 71 | * Simulation of any combination of hard lepton, hadron or photon |
| | 72 | scattering and soft hadron-hadron collisions in one package. |
| | 73 | |
| | 74 | * Colour coherence of partons (initial and final) in hard subprocesses |
| | 75 | |
| | 76 | * Heavy flavour hadron production and decay with QCD coherence effects |
| | 77 | |
| | 78 | * QCD jet evolution with soft gluon interference via angular ordering |
| | 79 | |
| | 80 | * Backward evolution of initial-state partons including interference |
| | 81 | |
| | 82 | * Azimuthal correlations within and between jets due to interference |
| | 83 | |
| | 84 | * Azimuthal correlations within jets due to gluon polarization |
| | 85 | |
| | 86 | * Cluster hadronization of jets via non-perturbative gluon splitting |
| | 87 | |
| | 88 | * A complete space-time picture from parton showers to hadronic decays |
| | 89 | |
| | 90 | * A colour rearrangement model based on an events space-time structure |
| | 91 | |
| | 92 | * A similar cluster model for soft and underlying hadronic events |
| | 93 | |
| | 94 | Further details may be found in the references cited above and at the |
| | 95 | end of this section, and in comments distributed throughout the code. |
| | 96 | |
| | 97 | The program operates by setting up parameters in common blocks and |
| | 98 | then calling a sequence of subroutines to generate an event. Para- |
| | 99 | meters not set in the main program HWIGPR are set to default values |
| | 100 | in the main initialisation routine HWIGIN. |
| | 101 | |
| | 102 | To generate events the user must first set up the beam particle names |
| | 103 | PART1, PART2 (type CHARACTER*8) in the common block /HWBEAM/, and the |
| | 104 | beam momenta PBEAM1, PBEAM2 (in GeV/c), a process code IPROC and the |
| | 105 | number of events required MAXEV in /HWPROC/. See section 5 for beams |
| | 106 | and processes available. |
| | 107 | |
| | 108 | All analysis of generated events (histogramming, etc.) should be |
| | 109 | performed by the user-provided routines HWABEG (to initialise), |
| | 110 | HWANAL (to analyse an event) and HWAEND (to terminate). At present |
| | 111 | HWANAL writes event information and stable particle data on unit |
| | 112 | LWEVT defined in HWIGIN (or simply returns if LWEVT=0). See HWANAL |
| | 113 | for details of event information written. Note that HWANAL should |
| | 114 | always begin with the line |
| | 115 | IF (IERROR.NE.0) RETURN |
| | 116 | to prevent it being executed for incomplete events. |
| | 117 | |
| | 118 | A detailed event summary is printed out for the first MAXPR events |
| | 119 | (default MAXPR=1). Set IPRINT=2 to list the particle identity codes |
| | 120 | and (simplified) particle decay schemes used in the program. |
| | 121 | |
| | 122 | The programming language is standard Fortran 77 as far as possible. |
| | 123 | However, the following may require modification for running on |
| | 124 | computers other than Vax's: |
| | 125 | |
| | 126 | * Most common blocks are inserted by INCLUDE 'HERWIG59.INC' Vax |
| | 127 | Fortran statements (see below for contents of HERWIG59.INC) |
| | 128 | |
| | 129 | * Subroutine HWUTIM (returning CPU time left) is machine dependent. |
| | 130 | |
| | 131 | The principal references are: |
| | 132 | |
| | 133 | G.Marchesini and B.R.Webber, Nucl. Phys. B310 (1988) 461; I.G. |
| | 134 | Knowles, Nucl. Phys. B310 (1988) 571; S.Catani, G.Marchesini and |
| | 135 | B.R.Webber, Nucl. Phys. B349 (1991) 635; G.Abbiendi and L.Stanco, |
| | 136 | Comp.Phys.Comm. 66 (1991) 16, Zeit. Phys. C51 (1991) 81; |
| | 137 | M.H.Seymour, Zeit. Phys. C56 (1992) 161. |
| | 138 | |
| | 139 | |
| | 140 | Some additional relevant references are: |
| | 141 | |
| | 142 | A.Bassetto, M.Ciafaloni and G.Marchesini, Phys. Rep. 100 (1983) 201; |
| | 143 | G. Marchesini and B.R. Webber, Nucl. Phys. B238 (1984) 1; Phys. |
| | 144 | Rev. D38 (1988) 3419; B. R. Webber, Nucl. Phys. B238 (1984) 492; |
| | 145 | Ann. Rev. Nucl. Part. Sci. 36 (1986) 253; I.G. Knowles, Nucl. Phys. |
| | 146 | B304 (1988) 794; Computer Phys. Comm. 58 (1990) 271. |
| | 147 | ------------------------------------------------------------------------ |
| | 148 | |
| | 149 | ****** 2. NEW FEATURES OF THIS VERSION ****** |
| | 150 | |
| | 151 | * The common block file HERWIG59.INC has been significantly rearranged |
| | 152 | and tidied up. |
| | 153 | |
| | 154 | * Many new hadrons have been added. All S & P wave mesons are present |
| | 155 | including the 1^P_0 & 3^P_1 states and many new, excited B^**, B_c & |
| | 156 | quarkonium states. Also all D wave kaons and some `light' I=3 states |
| | 157 | [pi_2, rho(1700) & rho_3]. All the baryons (singlet/octet/decuplet) |
| | 158 | containing up to one heavy (c,b) quark are included. |
| | 159 | |
| | 160 | --- Consequently the default parameters require retuning --- |
| | 161 | |
| | 162 | * New 8-character particle names have been introduced and the revised |
| | 163 | 7 digit PDG numbering scheme, as advocated in the LEP2 report, has |
| | 164 | been adopted. |
| | 165 | |
| | 166 | * The layout of HWUDAT has been altered to make it easier to identify |
| | 167 | and modify particle propeties. Three new arrays have been introduced |
| | 168 | RLTIM, RSPIN & IFLAV. These are: the particle's lifetime (ps), spin, |
| | 169 | and a code which specifies the flavour content of each hadron - used |
| | 170 | (in HWURES) to create sets of iso-flavour hadrons for cluster decay. |
| | 171 | Using the standard numbering of quark flavours the convention is: |
| | 172 | |
| | 173 | mesons: n_q n_qbar Eg. pi^+: 21, pi^-: 12 |
| | 174 | baryons: +/-n_q1 n_q2 n_q3 Eg. Xi^0: 332, Xi^0bar: -332 etc. |
| | 175 | (-ve for antibaryons; digits in decreasing order) |
| | 176 | |
| | 177 | Light, neutral mesons are identified as: 11 if I=1: pi^0,rho^0,... |
| | 178 | 33 if I=0: eta, eta'.. etc. |
| | 179 | |
| | 180 | Some parts of the program have been automated so that it is possible |
| | 181 | for the user to add new particles by specifying their properties via |
| | 182 | the arrays in /HWPROP/ & /HWUNAM/ and increasing NRES appropriately: |
| | 183 | this should be done before a call to HWUINC. |
| | 184 | |
| | 185 | As an example following lines add an isoscalar, spin pi state 'STAN' |
| | 186 | and a (very light) stable toponium state 'BEER' with the decay mode: |
| | 187 | STAN ---> BEER+BEER+BEER. |
| | 188 | |
| | 189 | NRES=NRES+1 |
| | 190 | RNAME(NRES)='STAN ' |
| | 191 | IDPDG(NRES)=666 |
| | 192 | IFLAV(NRES)=11 |
| | 193 | ICHRG(NRES)=0. |
| | 194 | RMASS(NRES)=0.5 |
| | 195 | RLTIM(NRES)=1.000D-10 |
| | 196 | RSPIN(NRES)=3.142 |
| | 197 | NRES=NRES+1 |
| | 198 | RNAME(NRES)='BEER ' |
| | 199 | IDPDG(NRES)=66 |
| | 200 | IFLAV(NRES)=66 |
| | 201 | ICHRG(NRES)=0. |
| | 202 | RMASS(NRES)=0.1 |
| | 203 | RLTIM(NRES)=1.000D+30 |
| | 204 | RSPIN(NRES)=0.0 |
| | 205 | CALL HWMODK(666,1.D0,0,66,66,66,0,0) |
| | 206 | |
| | 207 | |
| | 208 | * The mixing angles of all the light, I=0 mesons can now be set using: |
| | 209 | |
| | 210 | ETAMIX: eta <-> eta' F0MIX: f_0(1300) <-> f_0(980) |
| | 211 | PHIMIX: omega <-> phi, F1MIX: f_1(1285) <-> f_1(1510) |
| | 212 | H1MIX: h_1(1170) <-> h_1(1380) F2MIX: f_2 <-> f_2' |
| | 213 | |
| | 214 | * Using the logical arrays VTOCDK & VTORDK the production of specified |
| | 215 | particles can be stopped in both cluster decays and via the decay of |
| | 216 | other unstable resonances. |
| | 217 | |
| | 218 | * A priori weights for the relative production rates in cluster decays |
| | 219 | of mesons and baryons differing only via their S & L quantum numbers |
| | 220 | can be supplied using SNGWT & DECWT for singlet (i.e. Lambda-like) & |
| | 221 | decuplet baryons and REPWT for mesons. The old VECWT now corresponds |
| | 222 | to REPWT(0,1,0) and TENWT to REPWT(0,2,0). |
| | 223 | |
| | 224 | * The default masses of the c and b quarks have been lowered to 1.55 & |
| | 225 | 4.95 repectively: this corresponds to the mass of the lightest meson |
| | 226 | minus the u/d quark mass. This increases the number of heavy mesons, |
| | 227 | and hence total multiplicities, and slightly softens their momentum |
| | 228 | spectrum. The rate of photoproduced charm states increases and B-pi |
| | 229 | momentum correlations become smoother. |
| | 230 | |
| | 231 | * The resonance decay tables supplied in the program have been largely |
| | 232 | revised. Measured/expected modes with branching fraction at or above |
| | 233 | 1 per mille are given, including 4 & 5 body decays. To print the new |
| | 234 | tables call HWUDPR. |
| | 235 | |
| | 236 | * The arrays FBTM, FTOP & FHVY which stored the branching fractions of |
| | 237 | the bottom, top & heavier quarks' `partonic' decays are now nolonger |
| | 238 | used. Such decays are specified in the same way as all other decay |
| | 239 | modes: this permits different decays to be given to individual heavy |
| | 240 | hadrons. Partonic decays of charm hadrons and quarkonium states are |
| | 241 | also now supported. The products' order in a partonic decay mode is |
| | 242 | significant. For example if the decay is: Q --> W+q --> (f+fbar')+q, |
| | 243 | occuring inside a Q-sbar hadron the required ordering is: |
| | 244 | |
| | 245 | Q+sbar --->(f+fbar')+(q+sbar) |
| | 246 | or (q+fbar')+(f+sbar) `colour rearranged' |
| | 247 | |
| | 248 | In both cases the (V-A)^2 ME^2 is proportional to: p_0.p_2 * p_1*p_3 |
| | 249 | |
| | 250 | * The structure of the program has been altered so that secondary hard |
| | 251 | subrocess and subsequent fragmentation associated with each partonic |
| | 252 | heavy hadron decay appear separately. Thus pre-hadronization t quark |
| | 253 | decays are treated individually as are any subsequent bottom hadron |
| | 254 | partonic decays. |
| | 255 | |
| | 256 | * Additionally decays of heavy hadrons to exclusive non-partonic final |
| | 257 | states are supported. No check against double counting from partonic |
| | 258 | modes is included. However this isn't expected to be a major problem |
| | 259 | for the semi-leptonic and 2-body hadronic modes supplied. |
| | 260 | |
| | 261 | * An array NME has been introduced to enable a possible matrix element |
| | 262 | to be specified for each decay mode. |
| | 263 | |
| | 264 | NME = 0 Isotropic decay |
| | 265 | 100 Free particle (V-A)*(V-A): p_0.p_2 * p_1.p_3 |
| | 266 | 101 Bound quark (V-A)*(V-A): p_0.p_2 * p_1*[p_3 - xs*p_0] |
| | 267 | xs = m_Q/M_0 - spectator quark momentum fraction |
| | 268 | 130 Ore & Powell ortho-positronium ME^2: onium --> gg+g/gamma. |
| | 269 | |
| | 270 | The list of matrix elements presently supported is modest, users are |
| | 271 | urged to contact an author to have other MEs implimentated. |
| | 272 | |
| | 273 | * The decay tables can be written to/read from a file by using HWIODK, |
| | 274 | adopting the format advocated in the LEP2 report. In addition to the |
| | 275 | PDG numbering of particles the HERWIG numbers or character names can |
| | 276 | be used. This permits easy alteration of the decay tables. In HWUINC |
| | 277 | a call is made to HWUDKS which sets up HERWIGs internal pointers and |
| | 278 | performs some basic checks of the decay tables. Each decay mode must |
| | 279 | conserve charge and be kinematically allowed and not contain vetoed |
| | 280 | decay products. The sum of a particles branching ratios is set to 1. |
| | 281 | Also a warning is printed if an antiparticle does not have all the |
| | 282 | charge conjugate decays modes of the particle. |
| | 283 | |
| | 284 | * HWMODK enables changes to the decay tables to be made by alterating/ |
| | 285 | adding single decay modes including on an event by event basis. This |
| | 286 | can be done before HWUINC, in which case when altering the BR and/or |
| | 287 | ME code of an existing mode a warning is given of a duplicate second |
| | 288 | mode which supercedes the first. BRs set below 10^-6 are eliminated, |
| | 289 | whilst if one mode is within 10^-6 of 1 all other modes are removed. |
| | 290 | Note that some forethought is required if the BRs of 2 modes of the |
| | 291 | same particle are changed since the operation of rescaling to 1 the |
| | 292 | BR sum causes a non-commutativity in the order of the calls. |
| | 293 | |
| | 294 | * Production vertex information is now made available, using VHEP, for |
| | 295 | all partons, clusters and final state particles: set PRVTX=.TRUE. to |
| | 296 | print them. The vertices of partons and clusters are given wrt local |
| | 297 | coordinates associated with their individual hard sub-process. |
| | 298 | |
| | 299 | * All partonic and resonace rest frame lifetimes are generated with an |
| | 300 | exponential distribution: exp(-t/<tau>)/<tau>. The average lifetime, |
| | 301 | <tau>, is given in terms of the particles mass, width and virtuality |
| | 302 | by: |
| | 303 | hbar.sqrt(q^2) |
| | 304 | <tau>(q^2) = ----------------------------- |
| | 305 | \/(q^2-M^2)^2 + (Gamma.q^2/M)^2 |
| | 306 | |
| | 307 | = hbar/Gamma for an on-shell particle |
| | 308 | ~ hbar.q/(q^2-M^2) a highly virtual particle |
| | 309 | |
| | 310 | For partons an effective width = sqrt(VMIN2), to act as a cut-off on |
| | 311 | lifetimes, is introduced. |
| | 312 | |
| | 313 | * The space-time picture for cluster formation and splitting is partly |
| | 314 | ad hoc and partly string inspired - no physics depends upon it. |
| | 315 | |
| | 316 | * All particles with lifetimes greater than PLTCUT are set stable. |
| | 317 | |
| | 318 | * If PIPSMR=.TRUE. the primary interaction point's spatial position is |
| | 319 | is smeared according to the triple Gaussian in HWRPIP: this position |
| | 320 | is assigned to the CMF track. |
| | 321 | |
| | 322 | * If MAXDKL=.TRUE. then each putative decay is tested in HWDXLM to see |
| | 323 | that it occurs within a specified volume (cylinder/sphere for IOPDKL |
| | 324 | =1/2): if not it is set stable. |
| | 325 | |
| | 326 | * If MIXING=.TRUE. then B^0_d,s mesons are allowed to oscillate: XMIX |
| | 327 | and YMIX contain Delta-M/Gamma and Delta-gamma/2*Gamma respectively. |
| | 328 | A new particle, ISTHEP=200, is introduced giving the flavour of the |
| | 329 | neutral B meson at production in addition to the `decaying' track. |
| | 330 | |
| | 331 | * A multiple intra & inter-jet colour rearrangement model is available |
| | 332 | for CLRECO=.TRUE. The q-qbar pairings in two non-adjacent clusters |
| | 333 | are interchanged with probability PRECO if the distances between the |
| | 334 | production vertices of both q-qbar pairs when added in quadrature is |
| | 335 | reduced. EXAG can be used to artificially scale the lifetimes of any |
| | 336 | weak bosons. |
| | 337 | |
| | 338 | * A number of bugs have been corrected: in HWEPRO for weighted events; |
| | 339 | in HWSBRN affecting the reconstruction of the photon beam remnant; |
| | 340 | and in HWHEPG stopping event generation. Plus minor modifications to |
| | 341 | HWBGEN; in the use of HWHIGM by HWHIGJ; and small changes in HWHDIS |
| | 342 | & HWHEGG. |
| | 343 | |
| | 344 | * A significant bug in HWDHQK, affecting top quark decays, was present |
| | 345 | in version 5.8 ONLY. The scale of the top decay had been set to the |
| | 346 | b-quark mass, stopping gluon radiation from the b and restricting |
| | 347 | that from the W decay products to have transverse momentum less than |
| | 348 | the b mass. The scales are now correctly set for top decays. |
| | 349 | |
| | 350 | * Improved efficiency of photon generation in HWEGAM. |
| | 351 | |
| | 352 | * New hard sub-process have been added: |
| | 353 | |
| | 354 | - Compton scattering, gamma + q --> gamma + q, IPROC=5300. |
| | 355 | |
| | 356 | - Two-to-two parton scattering via exchange of a colour singlet |
| | 357 | IPROC=2400 Mueller-Tang pomeron: the fixed alpha_s and omega_0 are |
| | 358 | given by ASFIXD and OMEGA0 respectively. |
| | 359 | IPROC=2450 photon exchange, for like flavour qqbar pairs including |
| | 360 | the t-channel component of the interference with q-qbar -> q-qbar. |
| | 361 | |
| | 362 | - Drell-Yan has been extended to the production of all fermion pairs |
| | 363 | IPROC=1399; 1300 gives all quark flavours 1300+IQ a specific quark |
| | 364 | flavour, 1350 all leptons (including neutrinos) 1350+IL a specific |
| | 365 | lepton flavour. The s-channel component of the interference with |
| | 366 | like flavour q-qbar scattering is included here. |
| | 367 | |
| | 368 | - Z+jet production is included as IPROC=2150 (HWHW1J becomes HWHV1J) |
| | 369 | |
| | 370 | * Running coupling now used for prompt J/PSI production in DIS. |
| | 371 | |
| | 372 | * The phase-space limits for the momentum fraction of incoming photons |
| | 373 | in the Weizsacker-Williams approximation is now set by the variables |
| | 374 | YWWMIN & YWWMAX, allowing different ranges for the tagged and |
| | 375 | untagged photons in two-photon DIS. |
| | 376 | |
| | 377 | * Interfaced to the Schuler-Sjostrand parton distribution functions, |
| | 378 | version 2. These appear as PDFLIB sets with author group 'SaSph', |
| | 379 | but are actually implemented via a call to their SASGAM code. The |
| | 380 | value in MODPDF specifices the set (1-4 for 1D [recommended set],1M, |
| | 381 | 2D,2M), whether the Bethe-Heitler process is used for heavy flavours |
| | 382 | (add 10), whether the P^2-dependence is included (add 20), and which |
| | 383 | of their P^2 models is used (add 100 times their IP2 parameter). |
| | 384 | |
| | 385 | * New variables ANOMSC(1 or 2,IBEAM) record the evolution scale and Pt |
| | 386 | at which an anomalous (gamma* --> q+qbar) splitting was generated in |
| | 387 | the backward evolution of beam IBEAM. set 0 if no such splitting was |
| | 388 | generated. This is implemented in HWBGEN and HWSBRN. |
| | 389 | |
| | 390 | * In preparation for multiple interactions, several routines have been |
| | 391 | added or modified. New are: HWHREM for identifying and cleaning up |
| | 392 | the beam remnants; HWHSCT to administer the extra scatters. Minor |
| | 393 | modifications to: HWBGEN & HWSBRN, don't report energy conservation |
| | 394 | errors when ISLENT = -1; HWSSPC, improved approximation for remnant |
| | 395 | mass at high energies; and HWUPCM, improved safety against negative |
| | 396 | square roots. |
| | 397 | |
| | 398 | * Photon Initial State Radiation in e+e- annihilation events allowed. |
| | 399 | TMNISR sets the minimum s-hat/s value, ZMXISR sets the (arbitrary) |
| | 400 | separation between unresolved and resolved emission; using ZMXISR=0 |
| | 401 | switches off photon ISR. |
| | 402 | |
| | 403 | * Numerical integral in HWBDED now done analytically removing the need |
| | 404 | to reintegrate for each new energy; in principle allowing use in 5- |
| | 405 | jet WW events, but this is not yet implemented. |
| | 406 | |
| | 407 | * New phase-space variable WHMIN added. This sets the minimum allowed |
| | 408 | hadronic mass and affects photoproduction reactions (gamma-hadron & |
| | 409 | gamma-gamma) and DIS. In lepton-hadron DIS it is largely irrelevant |
| | 410 | since there is already a cut on Bjorken y which at fixed s is almost |
| | 411 | the same but for lepton-gamma DIS it makes a big difference. |
| | 412 | |
| | 413 | * A new treatment of running Higgs width and non-resonant diagrams, as |
| | 414 | suggested in M.H. Seymour, Phys. Lett. B354 (1995) 409. Selected by |
| | 415 | setting IOPHIG=2 or 3 (default); previous options 2 and 3 have been |
| | 416 | withdrawn. Note that including the non-resonant diagrams changes the |
| | 417 | meaning of what is generated: IOPHIG = 0 or 1, gives the s-channel |
| | 418 | diagram, an unphysical choice of part of the amplitude; IOPHIG = 2 |
| | 419 | or 3, gives the I=0 & J=0 part of the excess over the cross section |
| | 420 | expected for a zero mass Higgs boson, a physical choice of part of |
| | 421 | the cross section. The inclusion of non-resonant diagrams causes the |
| | 422 | cross section to increase below and decrease above resonance. |
| | 423 | |
| | 424 | * New treatment of the splitting in two of clusters containing hadron |
| | 425 | (or photon) remnants. Previous versions gave the 2 fragments a mass |
| | 426 | spectrum typical of soft processes: dn/dm**2 = Gaussian. In the new |
| | 427 | version the child containing the remnant is treated as before but |
| | 428 | the other cluster, containing a perturbative parton, is treated as a |
| | 429 | normal clusters: dn/dm = m**psplt. IOPREM controls this behaviour: 0 |
| | 430 | = old version, 1 = new (default). |
| | 431 | |
| | 432 | * Direct gamma+gamma* -> q+qbar is included in the hard correction for |
| | 433 | lepton-gamma DIS; plus minor bug fixed in HWBDIS. |
| | 434 | |
| | 435 | * The dummy routine IUCOMP has been removed, this avoids errors when |
| | 436 | the program is linked to CERNLIB. |
| | 437 | |
| | 438 | * It has been noticed that differences in the way quark masses are |
| | 439 | treated in different processes can cause inconsistencies between |
| | 440 | different ways of generating the same process. The most noticeable |
| | 441 | example is in direct photoproduction, where one can use process 9130 |
| | 442 | or 5000. See the note at the end of Section 5 of the documentation |
| | 443 | for more information on the strategies used in different processes. |
| | 444 | |
| | 445 | Version 5.1 of HERWIG was described in detail in Computer Physics |
| | 446 | Communications 67 (1992) 465. For completeness we list here also the |
| | 447 | main new features added in versions 5.2 - 5.7. |
| | 448 | |
| | 449 | In version 5.2: |
| | 450 | |
| | 451 | * New e+e- processes: |
| | 452 | - two photon processes, IPROC = 500+ID where ID=0-10 is the same as |
| | 453 | in Higgs processes for qqbar, llbar, and W+W-. The phase space is |
| | 454 | controlled by EMMIN,EMMAX for the CMF mass, PTMIN,PTMAX for the |
| | 455 | transverse momentum of the CMF in the lab, and CTMAX for the CMF |
| | 456 | angle of the outgoing particles. |
| | 457 | - photon-W fusion, IPROC = 550+ID where ID=0-9 is the same as in |
| | 458 | Higgs processes, except that ID=1 or 2 both give the sum of dubar |
| | 459 | and udbar etc. The phase space is controlled by EMMIN,EMMAX only. |
| | 460 | The full 2-->3 matrix elements for photon e-->f f'bar nu are used, |
| | 461 | so the cross section for real W production is correctly included. |
| | 462 | - ZZ pair production, IPROC=250 is treated just like WW production, |
| | 463 | and is based on the program kindly supplied by Zoltan Kunszt. |
| | 464 | |
| | 465 | * New ep processes: |
| | 466 | - the phase space for BGF is now controlled by EMMIN,EMMAX as above. |
| | 467 | The default values are 0 and RootS respectively, corresponding to |
| | 468 | the behaviour of version 5.1 |
| | 469 | - J/psi production from BGF, IPROC = 9104 is now available. |
| | 470 | - W W fusion to Higgs is now available in ep, IPROC = 9500+ID. |
| | 471 | |
| | 472 | * IPROC = 1600+ID now gives the sum of gluon fusion and q qbar fusion. |
| | 473 | This is especially important in e+e- if tan(beta) is large, when it |
| | 474 | is dominated by e+e- --> e+e- gamma gamma --> e+e- b bbar H. |
| | 475 | |
| | 476 | * Users can now force Z --> b bbar decays, with MODBOS(i)=7 (for a |
| | 477 | complete list see section 18). For example, IPROC=250, MODBOS(1)=7, |
| | 478 | MODBOS(2)=0 gives ZZ production with one Z decaying to b bbar. |
| | 479 | |
| | 480 | * All Higgs vertices now include an enhancement factor to account for |
| | 481 | non-SM couplings. ENHANC(ID), where ID=1-11 is the same as for Higgs |
| | 482 | production, holds the ratio of the AMPLITUDE for the given vertex to |
| | 483 | that of the SM. This of course only simulates the chargeless scalars |
| | 484 | of any extended model, and not the pseudoscalars or charged Higgses. |
| | 485 | |
| | 486 | * The heavy quark content of the photon now uses the corrections to |
| | 487 | the Drees-Grassie distribution functions for light quarks, recently |
| | 488 | calculated by C.S.Kim et al. (see M.Drees & C.S.Kim, DESY 91-039 and |
| | 489 | C.S.Kim, Durham preprint DTP/91/16). |
| | 490 | |
| | 491 | * A new structure function set, Owens1.1, similar to Duke+Owens1, but |
| | 492 | fitted to new data (Preprint FSU-HEP-910606) is available via |
| | 493 | NSTRU=5, and is now the default structure function set. |
| | 494 | |
| | 495 | In version 5.3: |
| | 496 | |
| | 497 | * O(alpha-s) jet production in ep processes has been included (IPROC= |
| | 498 | 9200 etc), with Q**2 range controlled by Q2MIN, Q2MAX and minimum |
| | 499 | jet transverse momentum (in the hard subprocess c.m. frame) set by |
| | 500 | PTMIN. The new subroutines were written by Sebastian Brandis and we |
| | 501 | are grateful to him for permission to use his code. |
| | 502 | |
| | 503 | * Minor bugs have been fixed in the backward evolution of quarks into |
| | 504 | photons, hadronic processes in e+e-, remnant hadronization in ep, |
| | 505 | and in the generation of weighted events (ie. with NOWGT=.FALSE.). |
| | 506 | |
| | 507 | In version 5.4: |
| | 508 | |
| | 509 | * A correction to hard gluon emission in e+e- events has been added |
| | 510 | and is now the default process. This uses the O(alpha-s) matrix |
| | 511 | element to add events in the `back-to-back' region of phase-space |
| | 512 | corresponding to a quark-antiquark pair recoiling from a very hard |
| | 513 | gluon. Although this is asymptotically negligible, and cannot be |
| | 514 | produced within the shower itself, it has a sizeable effect at LEP |
| | 515 | energies. As a result, the default parameters have been retuned, |
| | 516 | and show a marked improvement in agreement with OPAL data for event |
| | 517 | shapes sensitive to three-jet configurations (J.W. Gary, private |
| | 518 | communication). The uncorrected process has been retained for |
| | 519 | comparative purposes and is available as IPROC=120+IQ. |
| | 520 | |
| | 521 | * Photons are now included in time-like parton showering. The infra- |
| | 522 | red cutoff is VPCUT, which defaults to SQRT(S) corresponding to no |
| | 523 | emission. Agreement with LEP data is satisfactory if used together |
| | 524 | with the matrix element correction to produce photons in the back- |
| | 525 | to-back region. The results are insensitive to VPCUT variations |
| | 526 | in the range 0.1-1.0 GeV. |
| | 527 | |
| | 528 | * W decay correlations and width are now correctly included in W+jet |
| | 529 | production (previous versions used unpolarized, on-shell approx.). |
| | 530 | |
| | 531 | * An inconsistency in the argument used for alpha_s in the branching |
| | 532 | g -> q qbar has been removed. The change is a non-leading correction |
| | 533 | but leads to slightly more quarks in gluon jets. |
| | 534 | |
| | 535 | * A new parameter B1LIM has been introduced for B cluster hadroniz- |
| | 536 | ation. If MCL is the B cluster mass and MTH the threshold for its |
| | 537 | decay into 2 hadrons, the probability of its decay into a single B |
| | 538 | hadron is: 1 if MCL<MTH, 0 if MCL>(1+B1LIM)*MTH, with a linear |
| | 539 | interpolation i.e. 1-(MCL-MTH)/(B1LIM*MTH) if MTH<MCL<(1+B1LIM)*MTH. |
| | 540 | Thus the default value B1LIM=0 gives the same as previous versions, |
| | 541 | while B1LIM>0 gives a harder B spectrum. |
| | 542 | |
| | 543 | * B decays can now be performed by the EURODEC or CLEO Monte Carlo |
| | 544 | packages. The new variable BDECAY controls which package is used: |
| | 545 | 'HERW' for HERWIG; 'EURO' for EURODEC; 'CLEO' for CLEO. The EURODEC |
| | 546 | package can be obtained from the CERN library. The CLEO package is |
| | 547 | available by kind permission of the CLEO collaboration, and can be |
| | 548 | obtained from Luca Stanco at the address given above. |
| | 549 | |
| | 550 | In version 5.5: |
| | 551 | |
| | 552 | * The Sudakov form factors can now be calculated using the one-loop or |
| | 553 | two-loop alpha_s, according to the variable SUDORD (DEFAULT=1). The |
| | 554 | parton showering still incorporates the two-loop alpha_s in either |
| | 555 | case but if SUDORD=1 this is done using the veto algorithm, whereas |
| | 556 | if SUDORD=2 no vetoes are used in the final-state evolution. This |
| | 557 | means that the relative weight of any shower configuration can be |
| | 558 | calculated in a closed form, and hence that showers can be `forced'. |
| | 559 | For example, a package of routines should be available soon for |
| | 560 | forcing jets to contain photons, which will therefore drastically |
| | 561 | improve the efficiency of photon FSR studies. |
| | 562 | To next-to-leading order the two possibilities SUDORD=1 or 2 should |
| | 563 | be identical, but they differ at beyond-NLO, so some results may |
| | 564 | change a little. Previous versions were equivalent to SUDORD=1. |
| | 565 | |
| | 566 | * Alpha_em is now multiplied by the factor ALPFAC (DEFAULT=1) for all |
| | 567 | quark-photon vertices in jets, and in the `dead zone' in e+e-. This |
| | 568 | is a cheap way of improving the efficiency of photon FSR studies, |
| | 569 | which should not be needed once photon forcing is available. Note |
| | 570 | that results at small ycut become sensitive to ALPFAC above about 5. |
| | 571 | |
| | 572 | * A new parameter CLPOW (DEFAULT=2) is available in the cluster hadro- |
| | 573 | nization model. A cluster of mass MCL made of quarks of mass M1,M2 |
| | 574 | is split into lighter clusters before decaying if |
| | 575 | MCL**CLPOW > CLMAX**CLPOW + (M1+M2)**CLPOW |
| | 576 | Thus the previous value was CLPOW=2, like the new default. Smaller |
| | 577 | values will increase the yield of heavier clusters (and hence of |
| | 578 | baryons) for heavy quarks, without affecting light quarks much. For |
| | 579 | example, the default value gives no b-baryons (for the default value |
| | 580 | of CLMAX) whereas CLPOW=1.0 makes b-baryons/b-hadrons about 1/4. |
| | 581 | |
| | 582 | * The event record has been modified to retain entries for all partons |
| | 583 | before hadronization (with status ISTHEP=2). During hadronization, |
| | 584 | the gluons are split into quark-antiquark, while other partons are |
| | 585 | copied to a location (indicated by JDAHEP(1,*)) where their momenta |
| | 586 | may be shifted slightly, to conserve momentum, during heavy cluster |
| | 587 | splitting. Previously the original momenta were shifted, so momentum |
| | 588 | appeared not to be conserved at the parton level. |
| | 589 | |
| | 590 | * Minor improvements have been made to: NLO correction to Higgs decays |
| | 591 | to qqbar; pt spectra of outgoing electrons in two-photon processes; |
| | 592 | quark-mass effects in gamma-W fusion; WW spectrum below threshold in |
| | 593 | e+e-; t-bbar spectrum in W Drell-Yan (IPROC=1406). |
| | 594 | |
| | 595 | * Bugs preventing the use of Sudakov form factor tables from disk and |
| | 596 | gluon-> diquarks splitting option under some circumstances, together |
| | 597 | with other minor bugs and machine-dependences, have been fixed. |
| | 598 | |
| | 599 | In version 5.6: |
| | 600 | |
| | 601 | * Decays of very heavy quarks (top and higher generations) can occur |
| | 602 | either before or after hadronization. At present all top quarks will |
| | 603 | decay before/after hadronizing if the top mass is greater/less than |
| | 604 | 130 GeV. This can be changed in subroutine HWDTOP. All higher (>3) |
| | 605 | generations now decay before hadronization. Note that the new state- |
| | 606 | ment CALL HWDHQK must appear in the main program between the calls |
| | 607 | to HWBGEN and HWCFOR to carry out any decays before hadronization. |
| | 608 | |
| | 609 | * Bugs in the subroutine HWHDOA for O(alpha_s) jet production in DIS |
| | 610 | have been corrected by J. Chyla, who has also extended this process |
| | 611 | into the photoproduction region. If Q2MIN.LT.2D-6 (the new default), |
| | 612 | the kinematic lower limit on Q**2 is computed and used. New options |
| | 613 | IPROC=9250 to 9277 use various approximations to the neutral-current |
| | 614 | matrix element, as specified in the Table below. |
| | 615 | |
| | 616 | * The photoproduction processes have also been extended from the |
| | 617 | original heavy quark production program, to include all quark pair |
| | 618 | production (IPROC=9100-9106) and QCD Compton (IPROC=9110-9122), as |
| | 619 | well as the sum of the two (IPROC=9130). The possible flavours for |
| | 620 | the 9100,9110 and 9130 processes are limited by the input parameters |
| | 621 | IFLMIN and IFLMAX (defaults are 1 and 3, i.e. only u,d,s flavours). |
| | 622 | The corresponding Charged Current processes are now provided via the |
| | 623 | IPROC=9140-9144 codes. |
| | 624 | |
| | 625 | * All the DIS processes IPROC=9000-9599 are now available in e+e- as |
| | 626 | well as lepton-hadron collisions. The program generates a photon |
| | 627 | from the second beam (only) in Weizsacker-Williams approximation and |
| | 628 | uses Drees-Grassie structure functions for DIS on the photon. |
| | 629 | |
| | 630 | * Pointlike photon-hadron scattering to produce QCD jets is available |
| | 631 | as IPROC=5000. This is suitable for fixed-target photoproduction, |
| | 632 | provided events are generated in a frame in which the target has |
| | 633 | high momentum, and then boosted back to the lab. IPROC=5000+IQ gen- |
| | 634 | erates only those processes involving quark flavour IQ, using exact |
| | 635 | kinematics and light-cone momentum fraction. In both cases, after |
| | 636 | event generation the hard subprocess code IHPRO is set to 51,52 or |
| | 637 | 53 for photon+q->g+q, photon+qbar->g+qbar, or photon+g->q+qbar. |
| | 638 | |
| | 639 | * The default limits on Q**2 in DIS processes (Q2MIN,Q2MAX) have been |
| | 640 | set very small/large (0.0, 1.D10) and are reset to the kinematic |
| | 641 | limits unless changed by the user. This means the default Q2MIN is |
| | 642 | not suitable for simple NC DIS (IPROC=9000 etc), but is appropriate |
| | 643 | for jet and heavy quark photoproduction. |
| | 644 | |
| | 645 | * A new parameter NMXJET, the maximum number of outgoing partons in |
| | 646 | a hard subprocess (default 200) has been introduced in the common |
| | 647 | block file HERWIG56.INC. |
| | 648 | |
| | 649 | * For technical reasons, some HERWIG status codes ISTHEP between 153 |
| | 650 | and 165 have changed their meanings. See the Table in sect.10 below. |
| | 651 | |
| | 652 | * Bugs in the hadronization of diquark-antidiquark clusters have been |
| | 653 | fixed. Any such clusters with masses below threshold for decay into |
| | 654 | baryon-antibaryon are shifted to the threshold via a transfer of 4- |
| | 655 | momentum to a neighbouring cluster. |
| | 656 | |
| | 657 | * A bug in the default pion structure function (no gluons) is fixed. |
| | 658 | |
| | 659 | In version 5.7: |
| | 660 | |
| | 661 | - ELECTRO-WEAK COUPLINGS: New arrays QFCH(16), VFCH(16,2), AFCH(16,2) |
| | 662 | and VCKM(3,3) have been set up for couplings and CKM matrix. See the |
| | 663 | documentation file or HWIGIN for conventions. Note that universality |
| | 664 | is not assumed, so lepton axial couplings may differ for example; this |
| | 665 | is primarily to cover Z' possibilities, see below. The variable |
| | 666 | SCABI=sin^2 theta_Cabibbo is however also retained for the present. |
| | 667 | |
| | 668 | - A Z' has been introduced with PDG code 32, HERWIG identifier 202, |
| | 669 | default mass 500 GeV, width GAMZP (default 5 GeV) and name 'Z0PR'. |
| | 670 | It is invoked by setting ZPRIME=.TRUE. (default .FALSE.). |
| | 671 | |
| | 672 | - POLARISATION: incoming lepton and antilepton beam polarisations |
| | 673 | are now specified by setting two new vectors EPOLN(3) and PPOLN(3): |
| | 674 | component 3 is longitudinal and 1,2 transverse. Transverse only occurs |
| | 675 | in e+e- routines; recall that two transverse 'measurements' are needed |
| | 676 | to see an effect so it should not arise elsewhere. Note that in DIS |
| | 677 | processes you have to set either EPOLN if it is a lepton or (exclusive) |
| | 678 | PPOLN if an antilepton. |
| | 679 | |
| | 680 | Polarisation effects are now included in e+e- 2/3 jet production |
| | 681 | and Bjorken process, together with DIS processes apart from J/psi |
| | 682 | production. |
| | 683 | |
| | 684 | - NEW SUBPROCESSES: |
| | 685 | 2200 QCD direct photon pair production (inc. g+g->gamma+gamma) |
| | 686 | 5100+IQ Point-like photon/QCD heavy flavour pair production |
| | 687 | 5200+IQ Point-like photon/QCD heavy flavour single excitation |
| | 688 | The latter two replace 5000+IQ, while 5000 remains as before (ie |
| | 689 | a sum over all processes and flavours with simplified kinematics) |
| | 690 | |
| | 691 | - The kinematic reconstruction of DIS processes can now take place in |
| | 692 | the Breit frame, if BREIT=.TRUE. (the default value). Previous versions |
| | 693 | used the lab frame. Although the reconstruction is fully invariant under |
| | 694 | Lorentz boosts along the incoming hadron's direction, it is not under |
| | 695 | transverse boosts, so there should be some difference between the two |
| | 696 | frames. The boost is not performed for very small Q^2 (<10^-4) to avoid |
| | 697 | numerical instabilities, but the two frames are in any case equivalent |
| | 698 | for such small Q^2. |
| | 699 | |
| | 700 | - A new parameter PRSOF to produce an underlying event in only a fraction |
| | 701 | PRSOF of events (default=1.0). IPROC=19000 etc are thus equivalent to |
| | 702 | PRSOF=0. |
| | 703 | |
| | 704 | - Non-diffractive hadronic minimum bias events (IPROC=8000) can now be |
| | 705 | generated for a wider variety of beams (P,PBAR,PI+/-,K+/-,E+/-,MU+/-,GAMA |
| | 706 | on target P; also P and PBAR or leptons on target N). The event weight |
| | 707 | (previously set to 1.0 for this process) is the estimated cross section |
| | 708 | based on the parametrizations of Donnachie and Landshoff, CERN-TH.6635/92. |
| | 709 | The non-diffractive cross section is assumed to be 70% of the total. |
| | 710 | For lepton beams a photon is first generated using the effective photon |
| | 711 | approximation (see below) and then the on-shell photon cross section |
| | 712 | is used. |
| | 713 | |
| | 714 | - A bug has been fixed in HWBRAN and HWSBRN (present in versions 5.1 to |
| | 715 | 5.6) that led to too much transverse momentum being developed by the |
| | 716 | parton showers in hadron-hadron collisions. All radiation with pt |
| | 717 | greater than the hard process scale is now vetoed. In the case of |
| | 718 | initial-state radiation, this affects all events, while for final-state |
| | 719 | radiation it only affects those in which the two jets have a rapidity |
| | 720 | difference of more than about 3.4. |
| | 721 | |
| | 722 | - When SUDORD=2, no veto is needed for gluon splitting to quarks. This |
| | 723 | means that no vetoes are needed for final state showering, except for |
| | 724 | the previously-mentioned transverse momentum cut. The removal of |
| | 725 | vetoes allows preselection of the flavours that a jet will contain, |
| | 726 | giving a huge increase in the efficiency of rare process simulation. A |
| | 727 | package is already available to simulate heavy flavour production |
| | 728 | inside jets, and the equivalent for photons should soon be available. |
| | 729 | |
| | 730 | - Parameter BTCLM is now available to users to adjust the mass parameter |
| | 731 | in remnant formation. Its default value, 1.0, is identical to previous |
| | 732 | versions. |
| | 733 | |
| | 734 | - There is a new switch CLDIR for cluster decays. CLDIR=0 is the same as |
| | 735 | previous versions, while CLDIR=1 (the default) means that a cluster that |
| | 736 | contains a `perturbative' quark, ie one coming from the perturbative |
| | 737 | stage of the event (the hard process or perturbative gluon splitting) |
| | 738 | `remembers' its direction: when the cluster decays, the hadron carrying |
| | 739 | its flavour continues in the same direction (in the cluster c.m. frame) |
| | 740 | as the quark. This considerably hardens the spectrum of heavy hadrons, |
| | 741 | particularly of c- and b-flavoured hadrons. It also introduces a tendency |
| | 742 | for baryon-antibaryon pairs preferentially to align themselves with the |
| | 743 | event axis (the `TPC/2gamma string effect'). |
| | 744 | |
| | 745 | - The functionality of the routine HWUINE has now been split between it |
| | 746 | and a new routine, HWUFNE. A call to the latter MUST be inserted into |
| | 747 | the users main program, between the calls to HWMEVT and HWANAL. A |
| | 748 | check is built in to version 5.7 to prevent execution if this change |
| | 749 | is not made. See the documentation file for an example main program. |
| | 750 | We should also take this opportunity to remind users that the analysis |
| | 751 | routine HWANAL should begin with the line |
| | 752 | IF (IERROR.NE.0) RETURN |
| | 753 | since if an event is cancelled, each of the routines is still called |
| | 754 | in turn until reaching the end of the main loop. |
| | 755 | |
| | 756 | - If the new flag USECMF is .TRUE. (the default), events are boosted to |
| | 757 | their centre-of-mass frame before processing if necessary, and boosted |
| | 758 | back afterwards. This second boost is performed by the new routine |
| | 759 | HWUFNE, so it is essential that this is inserted in the correct place, |
| | 760 | as described above. |
| | 761 | |
| | 762 | - In hadronic processes with lepton beams (eg photoproduction in ep), |
| | 763 | the lepton->lepton+photon vertex now uses the full tranverse-momentum- |
| | 764 | dependent splitting function, with exact light-cone kinematics (i.e. |
| | 765 | the Equivalent Photon instead of the Weizsacker-Williams approximation). |
| | 766 | This means that the photon-hadron collision has a transverse momentum |
| | 767 | in the lepton-hadron frame, and must be boosted to a frame where it |
| | 768 | has no transverse momentum. Thus the cmf boost described above is |
| | 769 | always used in these processes, regardless of the value of USECMF. |
| | 770 | The correct lower energy cut-off appropriate to the hadronic process |
| | 771 | is applied to the photon, rather than the fixed cut of 5 GeV that |
| | 772 | was used in previous versions. The Q**2 of the photon is generated |
| | 773 | within the kinematically allowed limits, or the user-defined limits |
| | 774 | Q2WWMN and Q2WWMX (defaults 0 and 4) whichever is more restrictive. |
| | 775 | The momentum fraction is generated within the kinematic limits or |
| | 776 | between YBMIN and YBMAX (defaults 0 and 1). |
| | 777 | |
| | 778 | - Point-like photon processes (IPROC=5***) are now also available with |
| | 779 | lepton beams, using the Equivalent Photon Approximation. |
| | 780 | |
| | 781 | - Several minor improvements have been made to the O(as) processes in |
| | 782 | DIS (IPROC=91**): |
| | 783 | - A sign error has been corrected that led to the incorrect sign for |
| | 784 | the lepton-jet azimuthal correlation in QCD Compton processes. |
| | 785 | - An additional cut on the phase-space generation has been provided: |
| | 786 | the Bjorken-y variable (=Q^2/xs) is limited to range [YBMIN,YBMAX]. |
| | 787 | - BGSHAT=.FALSE. is now the default. |
| | 788 | - J/Psi production (IPROC=9107) now uses the EPA instead of the WWA, |
| | 789 | with the same phase-space cuts as hadronic processes with lepton |
| | 790 | beams, see above. |
| | 791 | |
| | 792 | - Many bugs have been fixed in the other O(as) process routines, HWHDOA |
| | 793 | and HWHDOM, ie for IPROC=92**. However, this process is no longer |
| | 794 | supported, and is only retained for comparative purposes. It will be |
| | 795 | withdrawn completely at the next version release. |
| | 796 | |
| | 797 | - An interface is now provided to Mark Gibbs' HERBVI package for baryon- |
| | 798 | number violation, and other multi-W production processes, IPROC=7***. |
| | 799 | |
| | 800 | - Minor bug fixes in HWHDIS, HWHEGW and HWHIGW and minor improvements in |
| | 801 | HWHHVY, HWHPHO, HWHQCD and HWHWEX hard process routines. |
| | 802 | |
| | 803 | - New fictional e+e- processes: e+e- -> gluon+gluon(+gluon), IPROC=107 |
| | 804 | & 127, treated just like e+e- -> quark+antiquark, summed over light |
| | 805 | quark flavours, for direct comparisons between quark and gluon jets. |
| | 806 | |
| | 807 | - New logical variable PRNDEC (default=.TRUE. unless NMXHEP>9999) causes |
| | 808 | track numbers in event listings to be printed in hexadecimal if.FALSE. |
| | 809 | This is necessary for very large events such as those generated by the |
| | 810 | HERBVI package (see above). |
| | 811 | |
| | 812 | - PDFLIB structure functions can now be used for the photon as well as |
| | 813 | nucleons. The new variable MODPHO acts just like MODPDF. PDFLIB calls |
| | 814 | have also been updated to allow for structure function sets with |
| | 815 | flavour-asymmetric sea contributions. |
| | 816 | |
| | 817 | - A logical inconsistency has been fixed in the decays of clusters to |
| | 818 | eta or eta' - previously all mixing was neglected, leading to double- |
| | 819 | counting and a significant over-estimate of the number of each. The |
| | 820 | new variable ETAMIX gives the eta_8/eta_0 mixing angle in degrees |
| | 821 | (default = -20). Rates are not very sensitive to its exact value, as |
| | 822 | the eta'/eta suppression is dominated by mass effects in the cluster |
| | 823 | model. |
| | 824 | |
| | 825 | - The maximum weight is now always printed in full precision (needed |
| | 826 | to be sure of generating the same events in repeated runs). |
| | 827 | |
| | 828 | - New constants: GEV2NB=389385 |
| | 829 | ALPHEM(1)=1./137(.03599) for Q^2=0. |
| | 830 | ALPHEM(2)=1./128 for Q^2~M_W^2 |
| | 831 | are introduced in various cross section formulae, and G_Fermi is |
| | 832 | eliminated. |
| | 833 | |
| | 834 | - The default top quark mass was increased to 150 GeV. |
| | 835 | |
| | 836 | In version 5.8 |
| | 837 | |
| | 838 | * A hard matrix element correction has been introduced in DIS (IPROC = |
| | 839 | 90**). This is switched on and off by the logical variable HARDME |
| | 840 | (default = .TRUE.). The method is essentially identical to the e+e- |
| | 841 | correction, generating first order matrix-element events in a |
| | 842 | phase-space region complementary to that of the parton shower. The |
| | 843 | e+e- correction is also now controlled by HARDME for consistency. |
| | 844 | |
| | 845 | * Soft matrix element corrections have been introduced in DIS and e+e- |
| | 846 | processes. These correct the distribution of emissions within the |
| | 847 | parton shower phase-space. It is similar to the method used in |
| | 848 | JETSET, except that the HARDEST emission is matched to the leading |
| | 849 | order matrix element, not the first as in JETSET. This ensures that |
| | 850 | the correction enters into the form factor, and not just the real |
| | 851 | emission probability. |
| | 852 | |
| | 853 | * In the backward evolution of initial-state radiation for photons the |
| | 854 | anomalous branching q-qbar <-- gamma has been introduced. |
| | 855 | |
| | 856 | * The treatment of forced branching of gluons and sea (anti-)quarks in |
| | 857 | backward evolution has been improved, by allowing it to occur at a |
| | 858 | random scale between the space-like cutoff QSPAC and the infrared |
| | 859 | cutoff, instead of exactly at QSPAC as before. |
| | 860 | A new option ISPAC=2 allows the freezing of structure functions at |
| | 861 | the scale QSPAC, while evolution continues to the infrared cutoff. |
| | 862 | The default, ISPAC=0 is equivalent to previous versions, in which |
| | 863 | perturbative evolution stops at QSPAC. |
| | 864 | |
| | 865 | * It is now possible to completely switch off initial-state radiation, |
| | 866 | by setting NOSPAC =.TRUE. Only the forced splitting of non-valence |
| | 867 | partons is generated. The default is (of course) NOSPAC =.FALSE. |
| | 868 | |
| | 869 | * An option to damp the parton distributions of off mass-shell photons |
| | 870 | relative on-shell photons, according to the scheme defined in Drees |
| | 871 | and Godbole MAD/PH/819 has been introduced. The adjustable parameter |
| | 872 | PHOMAS defines the crossover from the non-suppressed to suppressed |
| | 873 | regimes. Recommended values lie in the range QCDLAM to 1 GeV. The |
| | 874 | default value PHOMAS=0. corresponds to no suppression as in previous |
| | 875 | versions. |
| | 876 | |
| | 877 | * The interface to PDFLIB version 4 has been slightly changed. Instead |
| | 878 | of indicating a PDF set by a unique number, an `author group' string |
| | 879 | and set number are required. PDFLIB version 3 can still be used from |
| | 880 | HERWIG, simply by setting the author group to 'MODE'. It is also now |
| | 881 | possible to independently set the PDF set for each of the two beams. |
| | 882 | For example, if you previously used MRS D- for the proton and Gordon |
| | 883 | -Storrow set 1 for the photon, by setting |
| | 884 | MODPDF=47 |
| | 885 | MODPHO=231 |
| | 886 | You should now set |
| | 887 | AUTPDF(2)='MRS' |
| | 888 | MODPDF(2)=28 |
| | 889 | AUTPDF(1)='GS' |
| | 890 | MODPDF(1)=2 |
| | 891 | Alternatively, if you are still using PDFLIB version 3, you can set |
| | 892 | AUTPDF(2)='MODE' |
| | 893 | MODPDF(2)=47 |
| | 894 | AUTPDF(1)='MODE' |
| | 895 | MODPDF(1)=231 |
| | 896 | |
| | 897 | * In the CLDIR=1 option for cluster decays a new parameter CLSMR |
| | 898 | (default = 0.) allows a Gaussian smearing of the direction of the |
| | 899 | perturbative quark's momentum. The smearing is actually exponential |
| | 900 | in 1-cos(theta) with mean CLSMR. Thus increasing CLSMR decorrelates |
| | 901 | the cluster decay from the initial quark direction. |
| | 902 | |
| | 903 | * New subprocess have been added: |
| | 904 | |
| | 905 | - The direct, higher twist, production of light (u,d,s) L=0 mesons |
| | 906 | by point-like photons is now available: IPROC = 5500 all Spin =0,1 |
| | 907 | mesons, = 5510 only S=0 mesons; = 5520 only S=1 mesons. The vector |
| | 908 | mesons are produced with transverse or longitudinal polarisation |
| | 909 | |
| | 910 | and decayed accordingly. |
| | 911 | |
| | 912 | - High transverse momentum, scalar Higgs production, in association |
| | 913 | with a jet, is now available as IPROC =2300. Only the top quark is |
| | 914 | included in the loops with IAPHIG controlling the approx. used: =0 |
| | 915 | zero top mass limit; = 1 exact result; = 2 infinite top mass limit |
| | 916 | (default 1). Note the routines: HWHGJ1, HWHGJA, HWHGJB/C/D, HWUCI2 |
| | 917 | and HWULI2 use (non-standard FORTRAN-77) DOUBLE COMPLEX variables |
| | 918 | which may not be accepted by some compilers. Users can change to |
| | 919 | COMPLEX variables, however this involves a risk of rounding errors |
| | 920 | spoiling numerical cancellations. |
| | 921 | |
| | 922 | - DIS with neutrino beams is now available in processes IPROC= 90**. |
| | 923 | |
| | 924 | * The DIS O(alpha_s) jet production processes, IPROC = 92**, have been |
| | 925 | withdrawn and are no longer supported. |
| | 926 | |
| | 927 | * A running electromagnetic coupling has been introduced, HWUAEM(Q2). |
| | 928 | ALPHEM (now a single variable) sets the Thomson limit (Q2=0) value, |
| | 929 | default = 0.0072993 (1/137.0). |
| | 930 | |
| | 931 | * Two new particles have been created: 'REMG', IDHW=71, IDHEP=9998 and |
| | 932 | 'REMN', IDHW=72, IDHEP=9999 are remnant photons and nucleons |
| | 933 | respectively. They are identical to photons & nucleons, except that |
| | 934 | gluons are labelled as valence partons and, for the nucleon, valence |
| | 935 | quark distributions are set to zero. They are used internally by the |
| | 936 | JIMMY generator for multiple interactions, and are not intended for |
| | 937 | general use. |
| | 938 | |
| | 939 | * An error in setting the scale EMCMF (now called EMSCA) for QCD |
| | 940 | decays of colour neutral particles, preventing parton showers, has |
| | 941 | been corrected. |
| | 942 | |
| | 943 | * Minor bugs have been corrected in: phi decays to neutral kaons; the |
| | 944 | weights for photo-production processes; the value of EVWGT in di-jet |
| | 945 | production by point-like photons. |
| | 946 | |
| | 947 | * The transverse momentum cutoff for final-state photon emission from |
| | 948 | quarks, VPCUT, now defaults to 0.4 GeV. Previous versions defaulted |
| | 949 | to SQRT(S), switching off such emission. |
| | 950 | |
| | 951 | * The default top quark mass has been increased to 170 GeV/c^2 |
| | 952 | |
| | 953 | |
| | 954 | ------------------------------------------------------------------------ |
| | 955 | |
| | 956 | ****** 3. FEATURES NOT YET INCLUDED ****** |
| | 957 | |
| | 958 | Note that the following features are NOT yet included in the program: |
| | 959 | polarization of produced heavy quarks and leptons; treatment of |
| | 960 | coherence in the small-x region of incoming jets (see S. Catani, |
| | 961 | F. Fiorani and G. Marchesini, Nucl.Phys. B336(1990)18); multiple |
| | 962 | parton interactions and parton shadowing; diffractive processes; |
| | 963 | W/Z bosons within parton showers. |
| | 964 | |
| | 965 | ------------------------------------------------------------------------ |
| | 966 | |
| | 967 | ****** 4. PROGRAM STRUCTURE ****** |
| | 968 | |
| | 969 | The main program HWIGPR has the following form: |
| | 970 | |
| | 971 | PROGRAM HWIGPR |
| | 972 | C---COMMON BLOCKS ARE INCLUDED AS FILE HERWIG59.INC |
| | 973 | INCLUDE 'HERWIG59.INC' |
| | 974 | INTEGER N |
| | 975 | C---MAX NUMBER OF EVENTS THIS RUN |
| | 976 | MAXEV=100 |
| | 977 | C---BEAM PARTICLES |
| | 978 | PART1='PBAR' |
| | 979 | PART2='P' |
| | 980 | C---BEAM MOMENTA |
| | 981 | PBEAM1=900. |
| | 982 | PBEAM2=900. |
| | 983 | C---PROCESS |
| | 984 | IPROC=1500 |
| | 985 | C---INITIALISE OTHER COMMON BLOCKS |
| | 986 | CALL HWIGIN |
| | 987 | C---USER CAN RESET PARAMETERS AT |
| | 988 | C THIS POINT, OTHERWISE DEFAULT |
| | 989 | C VALUES IN HWIGIN WILL BE USED. |
| | 990 | PTMIN=100. |
| | 991 | C---COMPUTE PARAMETER-DEPENDENT CONSTANTS |
| | 992 | CALL HWUINC |
| | 993 | C---CALL HWUSTA TO MAKE ANY PARTICLE STABLE |
| | 994 | CALL HWUSTA('PI0 ') |
| | 995 | C---USER'S INITIAL CALCULATIONS |
| | 996 | CALL HWABEG |
| | 997 | C---INITIALISE ELEMENTARY PROCESS |
| | 998 | CALL HWEINI |
| | 999 | C---LOOP OVER EVENTS |
| | 1000 | DO 100 N=1,MAXEV |
| | 1001 | C---INITIALISE EVENT |
| | 1002 | CALL HWUINE |
| | 1003 | C---GENERATE HARD SUBPROCESS |
| | 1004 | CALL HWEPRO |
| | 1005 | C---GENERATE PARTON CASCADES |
| | 1006 | CALL HWBGEN |
| | 1007 | C---DO HEAVY QUARK DECAYS |
| | 1008 | CALL HWDHQK |
| | 1009 | C---DO CLUSTER FORMATION |
| | 1010 | CALL HWCFOR |
| | 1011 | C---DO CLUSTER DECAYS |
| | 1012 | CALL HWCDEC |
| | 1013 | C---DO UNSTABLE PARTICLE DECAYS |
| | 1014 | CALL HWDHAD |
| | 1015 | C---DO HEAVY FLAVOUR HADRON DECAYS |
| | 1016 | CALL HWDHVY |
| | 1017 | C---ADD SOFT UNDERLYING EVENT IF NEEDED |
| | 1018 | CALL HWMEVT |
| | 1019 | C---FINISH EVENT |
| | 1020 | CALL HWUFNE |
| | 1021 | C---USER'S EVENT ANALYSIS |
| | 1022 | CALL HWANAL |
| | 1023 | 100 CONTINUE |
| | 1024 | C---TERMINATE ELEMENTARY PROCESS |
| | 1025 | CALL HWEFIN |
| | 1026 | C---USER'S TERMINAL CALCULATIONS |
| | 1027 | CALL HWAEND |
| | 1028 | STOP |
| | 1029 | END |
| | 1030 | |
| | 1031 | Various phases of the simulation can be suppressed by deleting the |
| | 1032 | corresponding subroutine calls, or different subroutines may be |
| | 1033 | substituted. For example, in studies at the parton level everything |
| | 1034 | from CALL HWDHQK to CALL HWMEVT can be omitted. |
| | 1035 | |
| | 1036 | The following is a full list of subroutines and functions, which are |
| | 1037 | classified according to their initial letters, except when standard- |
| | 1038 | ization agreements take precedence. |
| | 1039 | |
| | 1040 | +--------+---------------------------------------------+ |
| | 1041 | | Name | Description | |
| | 1042 | +--------+---------------------------------------------+ |
| | 1043 | | Main program and initialization | |
| | 1044 | +--------+---------------------------------------------+ |
| | 1045 | | HWIGPR | Main program | |
| | 1046 | | HWIGIN | Default initializations | |
| | 1047 | +--------+---------------------------------------------+ |
| | 1048 | | Reading/writing/altering decay modes | |
| | 1049 | +--------+---------------------------------------------+ |
| | 1050 | | HWIODK | Inputs/outputs formatted decay tables | |
| | 1051 | | HWMODK | Modifies or adds an individual decay mode | |
| | 1052 | +--------+---------------------------------------------+ |
| | 1053 | | User-provided analysis routines | |
| | 1054 | +--------+---------------------------------------------+ |
| | 1055 | | HWABEG | Initializes user's analysis | |
| | 1056 | | HWAEND | Terminates user's analysis | |
| | 1057 | | HWANAL | Performs user's analysis on event | |
| | 1058 | +--------+---------------------------------------------+ |
| | 1059 | | Parton branching with interfering gluons | |
| | 1060 | +--------+---------------------------------------------+ |
| | 1061 | | HWBAZF | Computes azimuthal correlation functions | |
| | 1062 | | HWBCON | Makes colour connections between jets | |
| | 1063 | | HWBDED | Correction to the `dead zone' in e+e- | |
| | 1064 | | HWBDIS | Correction to the `dead zone' in DIS | |
| | 1065 | | HWBFIN | Transfers external lines of jet to /HEPEVT/ | |
| | 1066 | | HWBGEN | Finds unevolved partons and generates jets | |
| | 1067 | | HWBJCO | Combines jets with correct kinematics | |
| | 1068 | | HWBMAS | Computes masses and trans. momenta in jet | |
| | 1069 | | HWBRAN | Generates a timelike parton branching | |
| | 1070 | | HWBSPA | Computes momenta in spacelike jet | |
| | 1071 | | HWBSPN | Computes spin density/decay matrices | |
| | 1072 | | HWBSU1 | First term in quark Sudakov form factor | |
| | 1073 | | HWBSU2 | Second term in quark Sudakov form factor | |
| | 1074 | | HWBSUD | Computes (or reads) Sudakov form factors | |
| | 1075 | | HWBSUG | Integrand in gluon Sudakov form factor | |
| | 1076 | | HWBSUL | Logarithmic part of Sudakov form factor | |
| | 1077 | | HWBTIM | Computes momenta in timelike jet | |
| | 1078 | | HWBVMC | Virtual mass cutoff for parton type ID | |
| | 1079 | +--------+---------------------------------------------+ |
| | 1080 | | Cluster hadronization model | |
| | 1081 | +--------+---------------------------------------------+ |
| | 1082 | | HWCCUT | Cuts a massive cluster in two | |
| | 1083 | | HWCDEC | Decays clusters into primary hadrons | |
| | 1084 | | HWCFLA | Sets up flavours for HWCHAD | |
| | 1085 | | HWCFOR | Forms clusters | |
| | 1086 | | HWCGSP | Splits gluons | |
| | 1087 | | HWCHAD | Decays a cluster into one or two hadrons | |
| | 1088 | +--------+---------------------------------------------+ |
| | 1089 | | Particle and heavy quark decays | |
| | 1090 | +--------+---------------------------------------------+ |
| | 1091 | | HWDBOS | Finds and decays W and Z bosons | |
| | 1092 | | HWDBOZ | Chooses decay mode of W and Z bosons | |
| | 1093 | | HWDCLE | Interface to CLEO package for B decays | |
| | 1094 | | HWDCHK | Checks given decay mode is self-consistent | |
| | 1095 | | HWDFOR | Generates a four-body decay | |
| | 1096 | | HWDFIV | Generates a five-body decay | |
| | 1097 | | HWDEUR | Interface to EURODEC package for B decays | |
| | 1098 | | HWDHAD | Generates decays of unstable hadrons | |
| | 1099 | | HWDHGC | Higgs -> gamma gamma decay | |
| | 1100 | | HWDHGF | Higgs -> W+ W- decay | |
| | 1101 | | HWDHIG | Finds and decays Higgs bosons | |
| | 1102 | | HWDHQK | Finds and decays heavy quarks | |
| | 1103 | | HWDHVY | Finds and decays heavy flavour hadrons | |
| | 1104 | | HWDIDP | Chooses a parton for HWDHVY | |
| | 1105 | | HWDPWT | Phase space decay weight | |
| | 1106 | | HWDTHR | Generates a three-body decay | |
| | 1107 | | HWDTOP | Decides whether to decay top quark | |
| | 1108 | | HWDTWO | Generates a two-body decay | |
| | 1109 | | HWDWWT | Weak (V-A) decay weight | |
| | 1110 | | HWDXLM | Tests if decay vertex lies in given volume | |
| | 1111 | +--------+---------------------------------------------+ |
| | 1112 | | Elementary subprocess generation | |
| | 1113 | +--------+---------------------------------------------+ |
| | 1114 | | HWEFIN | Final calculations on elementary subprocess | |
| | 1115 | | HWEGAM | Generates Weizsacker-Williams photon | |
| | 1116 | | HWEINI | Initializes elementary subprocess | |
| | 1117 | | HWEISR | Generates a photon fron initial e or mu | |
| | 1118 | | HWEONE | Sets up a 2->1 hard subprocess | |
| | 1119 | | HWEPRO | Generates elementary subprocess | |
| | 1120 | | HWETWO | Sets up a 2->2 hard subprocess | |
| | 1121 | +--------+---------------------------------------------+ |
| | 1122 | | Individual hard subprocesses | |
| | 1123 | +--------+---------------------------------------------+ |
| | 1124 | | HWHBGF | Hard subprocess: boson-gluon fusion (BGF) | |
| | 1125 | | HWHBKI | Computes kinematics for BGF | |
| | 1126 | | HWHBRN | Returns a phase-space point for BGF | |
| | 1127 | | HWHBSG | Computes cross section for BGF | |
| | 1128 | | HWHDIS | Hard subprocess: deep inelastic lepton quark| |
| | 1129 | | HWHDYP | Hard subprocess: Drell-Yan Z0/photon prodn | |
| | 1130 | | HWHEGG | Hard subprocess: two-photon processes in ee | |
| | 1131 | | HWHEGW | Hard subprocess: photon-W processes in e+e- | |
| | 1132 | | HWHEGX | Calculates cross section for HWHEGW | |
| | 1133 | | HWHEPA | Hard subprocess: e+e- -> f fbar | |
| | 1134 | | HWHEPG | Hard subprocess: e+e- -> q qbar gluon | |
| | 1135 | | HWHEW0 | e+e- -> W W / Z Z subroutine | |
| | 1136 | | HWHEW1 | e+e- -> W W / Z Z subroutine | |
| | 1137 | | HWHEW2 | e+e- -> W W / Z Z subroutine | |
| | 1138 | | HWHEW3 | e+e- -> W W subroutine | |
| | 1139 | | HWHEW4 | e+e- -> W W / Z Z subroutine | |
| | 1140 | | HWHEW5 | e+e- -> Z Z subroutine | |
| | 1141 | | HWHEWW | Hard subprocess: e+e- -> W W / Z Z | |
| | 1142 | | HWHHVY | Hard subprocess: heavy quark production | |
| | 1143 | | HWHIG1 | Matrix elements for Higgs + jet production | |
| | 1144 | | HWHIGA | Amplitudes squared for Higgs + jet | |
| | 1145 | | HWHIGB | Loop integrals for Higgs + jet | |
| | 1146 | | HWHIGJ | QCD Higgs + jet production | |
| | 1147 | | HWHIGM | Choose Higgs mass for production routines | |
| | 1148 | | HWHIGS | Hard subprocess: gg/qqbar -> Higgs | |
| | 1149 | | HWHIGT | Computes gg -> Higgs cross section | |
| | 1150 | | HWHIGW | Hard subprocess: WW / ZZ -> Higgs | |
| | 1151 | | HWHIGY | Computes ee -> Z -> ZH cross section | |
| | 1152 | | HWHIGZ | Hard subprocess: ee -> Z -> ZH | |
| | 1153 | | HWHPH2 | Hard subprocess: direct photon pairs | |
| | 1154 | | HWHPHO | Hard subprocess: direct photon production | |
| | 1155 | | HWHPPB | Box contribution to gg->photon photon | |
| | 1156 | | HWHPPE | Pointlike photon-parton (fixed flavour) | |
| | 1157 | | HWHPPH | Pointlike photon-parton (fixed pair flavour)| |
| | 1158 | | HWHPPM | Pointlike photon-parton direct light meson | |
| | 1159 | | HWHPPT | Pointlike photon-parton (all flavours) | |
| | 1160 | | HWHQPS | Pointlike photon-quark (Compton) scattering | |
| | 1161 | | HWHQCD | Hard subprocess: QCD 2->2 | |
| | 1162 | | HWHQCP | Identifies QCD 2->2 hard subprocess | |
| | 1163 | | HWHREM | Treats hard scattering remnants | |
| | 1164 | | HWHSCT | Process extra hard scatterings | |
| | 1165 | | HWHSNG | Colour singlet parton scattering | |
| | 1166 | | HWHSNM | Colour singlet parton scattering ME | |
| | 1167 | | HWHV1J | Hard subprocess W/Z + jet production | |
| | 1168 | | HWHWEX | Top production by W exchange | |
| | 1169 | | HWHWPR | Hard subprocess: W production | |
| | 1170 | +--------+---------------------------------------------+ |
| | 1171 | | Soft minimum-bias or underlying event | |
| | 1172 | +--------+---------------------------------------------+ |
| | 1173 | | HWMEVT | Generates min bias or soft underlying event | |
| | 1174 | | HWMLPS | Generates longitudinal phase space | |
| | 1175 | | HWMNBI | Computes negative binomial probability | |
| | 1176 | | HWMULT | Chooses min bias charged multiplicity | |
| | 1177 | | HWMWGT | Calculates weight for minimum bias events | |
| | 1178 | +--------+---------------------------------------------+ |
| | 1179 | | Random number generators | |
| | 1180 | +--------+---------------------------------------------+ |
| | 1181 | | HWRAZM | Randomly rotated azimuth | |
| | 1182 | | HWREXP | Random number: exponential distribution | |
| | 1183 | | HWREXQ | Random number: exp. dist. with cutoff | |
| | 1184 | | HWREXT | Random number: exponential transverse mass | |
| | 1185 | | HWRGAU | Random number: Gaussian | |
| | 1186 | | HWRGEN | Random number generator (l'Ecuyer method) | |
| | 1187 | | HWRINT | Random integer | |
| | 1188 | | HWRLOG | Random logical | |
| | 1189 | | HWRPIP | Random primary interaction point | |
| | 1190 | | HWRPOW | Random number: power distribution | |
| | 1191 | | HWRUNG | Random number: uniform + Gaussian tails | |
| | 1192 | | HWRUNI | Random number: uniform | |
| | 1193 | +--------+---------------------------------------------+ |
| | 1194 | | Spacelike branching of incoming partons | |
| | 1195 | +--------+---------------------------------------------+ |
| | 1196 | | HWSBRN | Generates spacelike parton branching | |
| | 1197 | | HWSDGG | Drees-Grassie photon str. function (gluon) | |
| | 1198 | | HWSDGQ | Drees-Grassie photon str. function (quarks) | |
| | 1199 | | HWSFBR | Chooses a spacelike branching | |
| | 1200 | | HWSFUN | Hadron structure functions | |
| | 1201 | | HWSGAM | Gamma function (for structure functions) | |
| | 1202 | | HWSGEN | Generates x values for spacelike partons | |
| | 1203 | | HWSGQQ | Inserts g->q qbar part of gluon form factor | |
| | 1204 | | HWSSPC | Replaces spacelike partons by spectators | |
| | 1205 | | HWSSUD | Sudakov form factor/structure function | |
| | 1206 | | HWSTAB | Interpolates in function table (for HWSSUD) | |
| | 1207 | | HWSVAL | Checks for valence parton | |
| | 1208 | +--------+---------------------------------------------+ |
| | 1209 | | Miscellaneous utilities | |
| | 1210 | +--------+---------------------------------------------+ |
| | 1211 | | HWUAEM | Running electromagnetic coupling constant | |
| | 1212 | | HWUAER | Real part of photon self-energy | |
| | 1213 | | HWUALF | Two-loop QCD running coupling constant | |
| | 1214 | | HWUANT | Finds a particle's antiparticle | |
| | 1215 | | HWUBPR | Prints branching data for last parton shower| |
| | 1216 | | HWUBST | Boost event record to/from hadron-hadron cmf| |
| | 1217 | | HWUCFF | Coefficients for e+e- and DIS cross sections| |
| | 1218 | | HWUCI2 | Logarithmic integral Ci_2 | |
| | 1219 | | HWUDAT | Block data: particle properties | |
| | 1220 | | HWUDKL | Generates decay vertex of unstable particle | |
| | 1221 | | HWUDKS | Converts decay modes into internal format | |
| | 1222 | | HWUDPR | Prints particle properties and decay modes | |
| | 1223 | | HWUECM | Centre-of-mass energy | |
| | 1224 | | HWUEDT | Insert or delete entries in the event record| |
| | 1225 | | HWUEEC | Computes coefficients for e+e- cross section| |
| | 1226 | | HWUEPR | Prints event data | |
| | 1227 | | HWUEMV | Moves entries within the event record | |
| | 1228 | | HWUFNE | Finishes an event | |
| | 1229 | | HWUGAU | Adaptive Gaussian integration | |
| | 1230 | | HWUIDT | Translates particle identity codes | |
| | 1231 | | HWUINC | Initial parameter-dependent calculations | |
| | 1232 | | HWUINE | Initializes an event | |
| | 1233 | | HWULB4 | Boost: rest frame -> lab, no masses assumed | |
| | 1234 | | HWULDO | Lorentz 4-vector dot product | |
| | 1235 | | HWULF4 | Boost: lab frame -> rest, no masses assumed | |
| | 1236 | | HWULI2 | Logarithmic integral Li_2 (Spence function) | |
| | 1237 | | HWULOB | Lorentz transformation: rest frame -> lab | |
| | 1238 | | HWULOF | Lorentz transformation: lab -> rest frame | |
| | 1239 | | HWULOR | Multiplies by Lorentz matrix | |
| | 1240 | | HWUMAS | Puts mass in 5th component of vector | |
| | 1241 | | HWUPCM | Centre-of-mass momentum | |
| | 1242 | | HWURAP | Rapidity | |
| | 1243 | | HWURES | Computes/prints resonance data | |
| | 1244 | | HWUROB | Rotation by inverse of matrix R | |
| | 1245 | | HWUROF | Rotation by matrix R | |
| | 1246 | | HWUROT | Computes rotation R from vector to z-axis | |
| | 1247 | | HWUSOR | Sorts an array in ascending order | |
| | 1248 | | HWUSQR | Square root with sign retention | |
| | 1249 | | HWUSTA | Makes a particle type stable | |
| | 1250 | | HWUTAB | Interpolates in a table | |
| | 1251 | | HWUTIM | Checks time remaining (N.B. VAX Fortran) | |
| | 1252 | +--------+---------------------------------------------+ |
| | 1253 | | Vector manipulation | |
| | 1254 | +--------+---------------------------------------------+ |
| | 1255 | | HWVDIF | Vector difference | |
| | 1256 | | HWVDOT | Vector dot product | |
| | 1257 | | HWVEQU | Vector equality | |
| | 1258 | | HWVSCA | Vector times scalar | |
| | 1259 | | HWVSUM | Vector sum | |
| | 1260 | | HWVZRO | Vector zero | |
| | 1261 | +--------+---------------------------------------------+ |
| | 1262 | | Warning messages and error handling | |
| | 1263 | +--------+---------------------------------------------+ |
| | 1264 | | HWWARN | Issues warnings and deals with errors | |
| | 1265 | +--------+---------------------------------------------+ |
| | 1266 | |
| | 1267 | N.B. Dummy versions of the external routines |
| | 1268 | |
| | 1269 | PDFSET STRUCTM |
| | 1270 | EUDINI FRAGMT IEUPDG IPDGEU |
| | 1271 | DECADD QQINIT QQLMAT |
| | 1272 | HVCBVI HVHBVI |
| | 1273 | |
| | 1274 | should be deleted if the structure function library, EURODEC B decay |
| | 1275 | package, CLEO B decay package, or HERBVI (respectively) is linked. |
| | 1276 | ------------------------------------------------------------------------ |
| | 1277 | |
| | 1278 | ****** 5. BEAMS AND PROCESSES ****** |
| | 1279 | |
| | 1280 | As indicated above, a number of variables must be set in the main |
| | 1281 | program to specify what is to be simulated: |
| | 1282 | |
| | 1283 | |
| | 1284 | +----------+----------------------------------+-----------+ |
| | 1285 | | Name | Description | Default | |
| | 1286 | +----------+----------------------------------+-----------+ |
| | 1287 | | PART1 | Type of particle in beam 1 | 'PBAR '| |
| | 1288 | | PART2 | Type of particle in beam 2 | 'P '| |
| | 1289 | | PBEAM1 | Momentum of beam 1 | 900. | |
| | 1290 | | PBEAM2 | Momentum of beam 2 | 900. | |
| | 1291 | | IPROC | Type of process to generate | 1500 | |
| | 1292 | | MAXEV | Number of events to generate | 100 | |
| | 1293 | +----------+----------------------------------+-----------+ |
| | 1294 | |
| | 1295 | |
| | 1296 | The beam particle types PART1,PART2 supported at present are: |
| | 1297 | |
| | 1298 | |
| | 1299 | +---------------------------------------------+ |
| | 1300 | | 'E+ ','E- ','MU+ ','MU- ' | |
| | 1301 | | 'NUE ','NUEB ','NUMU ','NMUB ' | |
| | 1302 | | 'NTAU ','NTAB ','GAMA ' | |
| | 1303 | | 'P ','PBAR ','N ','NBAR ' | |
| | 1304 | | 'PI+ ','PI- ' | |
| | 1305 | +---------------------------------------------+ |
| | 1306 | |
| | 1307 | In addition, beams 'K+ ' and 'K- ' are supported for |
| | 1308 | minimum bias non-diffractive soft hadronic events (IPROC=8000) only. |
| | 1309 | |
| | 1310 | The currently available processes IPROC are tabulated below. |
| | 1311 | |
| | 1312 | +---------+--------------------------------------------------------+ |
| | 1313 | | IPROC | Process | |
| | 1314 | +---------+--------------------------------------------------------+ |
| | 1315 | | 100 | e+ e- -> q qbar (gluon) (all flavours) | |
| | 1316 | | 100+IQ | e+ e- -> q qbar (gluon) (IQ=1--6 for q=d,u,s,c,b,t) | |
| | 1317 | | 107 | e+ e- -> gluon gluon (gluon) fictitious process | |
| | 1318 | | 110 | e+ e- -> q qbar gluon (all flavours) | |
| | 1319 | | 110+IQ | e+ e- -> q qbar gluon (IQ as above) | |
| | 1320 | | 120 | e+ e- -> q qbar (all flavours)| without correction to | |
| | 1321 | | 120+IQ | e+ e- -> q qbar (IQ as above) | hard gluon branching | |
| | 1322 | | 127 | e+ e- -> gluon gluon | | |
| | 1323 | | 150+IL | e+ e- -> l lbar (IL=2,3 for l=mu,tau) | |
| | 1324 | +---------+--------------------------------------------------------+ |
| | 1325 | | 200 | e+ e- -> W+ W- (see sect. 18 on control of W/Z decays)| |
| | 1326 | | 250 | e+ e- -> Z0 Z0 (see sect. 18 on control of W/Z decays)| |
| | 1327 | +---------+--------------------------------------------------------+ |
| | 1328 | | 300 | e+ e- -> Z H -> Z q qbar (all flavours) | |
| | 1329 | | 300+IQ | e+ e- -> Z H -> Z q qbar (IQ as above) | |
| | 1330 | | 306+IL | e+ e- -> Z H -> Z l lbar (IL=1,2,3 for l=e,mu,tau) | |
| | 1331 | | 310,11 | e+ e- -> Z H -> Z W W, Z Z Z | |
| | 1332 | | 312 | e+ e- -> Z H -> Z gamma gamma | |
| | 1333 | | 399 | e+ e- -> Z H -> Z anything | |
| | 1334 | +---------+--------------------------------------------------------+ |
| | 1335 | | 400+ID | e+ e- -> nu nu H + e e H (ID as in IPROC=300+ID) | |
| | 1336 | +---------+--------------------------------------------------------+ |
| | 1337 | | 500+ID | e+ e- -> gamma gamma -> qqbar/llbar/WW (ID=0-10 as in | |
| | 1338 | | | IPROC=300+ID) | |
| | 1339 | | 550+ID | e+ e- -> gamma W -> qq'bar/ll'bar (ID=0-9) | |
| | 1340 | +---------+--------------------------------------------------------+ |
| | 1341 | | 1300 | q qbar -> Z0/gamma -> q qbar (all flavours) | |
| | 1342 | | 1300+IQ | q qbar -> Z0/gamma -> q qbar (IQ as above) | |
| | 1343 | | 1350 | q qbar -> Z0/gamma -> l lbar (all lepton species) | |
| | 1344 | | 1350+IL | q qbar -> Z0/gamma -> l lbar (IL=1-6 for e,enu,mu,etc) | |
| | 1345 | | 1399 | q qbar -> Z0/gamma -> anything | |
| | 1346 | +---------+--------------------------------------------------------+ |
| | 1347 | | 1400 | q qbar -> W+/- -> q' qbar'' (all flavours) | |
| | 1348 | | 1400+IQ | q qbar -> W+/- -> q' qbar'' (q' or q'' as above) | |
| | 1349 | | 1450 | q qbar -> W+/- -> l nul (all lepton species) | |
| | 1350 | | 1450+IL | q qbar -> W+/- -> l nul (IL=1-3 as above) | |
| | 1351 | | 1499 | q qbar -> W+/- -> anything | |
| | 1352 | +---------+--------------------------------------------------------+ |
| | 1353 | | 1500 | QCD 2 -> 2 hard parton scattering | |
| | 1354 | | | After generation, IHPRO is subprocess (see list) | |
| | 1355 | +---------+--------------------------------------------------------+ |
| | 1356 | | 1600+ID | q qbar/g g -> Higgs (ID as in IPROC=300+ID) | |
| | 1357 | +---------+--------------------------------------------------------+ |
| | 1358 | | 1700+IQ | QCD heavy quark production (IQ as above) | |
| | 1359 | | | After generation, IHPRO is subprocess (see list) | |
| | 1360 | +---------+--------------------------------------------------------+ |
| | 1361 | | 1800 | QCD direct photon + jet production | |
| | 1362 | | | After generation, IHPRO is subprocess (see list) | |
| | 1363 | +---------+--------------------------------------------------------+ |
| | 1364 | | 1900+ID | q qbar -> q' qbar' H (ID as in IPROC=300+ID) | |
| | 1365 | +---------+--------------------------------------------------------+ |
| | 1366 | | 2000 | t production via W exchange (sum of 2001-2008) | |
| | 1367 | | 2001,2 | ubar bbar -> dbar tbar, d bbar -> u tbar | |
| | 1368 | | 2003,4 | dbar bbar -> ubar tbar, u b -> d t | |
| | 1369 | | 2005,6 | cbar bbar -> sbar tbar, s bbar -> c tbar | |
| | 1370 | | 2007,8 | sbar b -> cbar t , c b -> s t | |
| | 1371 | +---------+--------------------------------------------------------+ |
| | 1372 | | 2100 | Vector boson + jet production. | |
| | 1373 | | 2110,20 | Compton only (g q -> V q), annih. only (q qbar -> V g) | |
| | 1374 | +---------+--------------------------------------------------------+ |
| | 1375 | | 2200 | QCD direct photon pair production (see list for IHPRO) | |
| | 1376 | +---------+--------------------------------------------------------+ |
| | 1377 | | 2300 | QCD Higgs plus jet production (see list for IHPRO) | |
| | 1378 | +---------+--------------------------------------------------------+ |
| | 1379 | | 2400 | Mueller-Tang colour singlet exchange | |
| | 1380 | | 2450 | Quark scattering via photon exchange | |
| | 1381 | +---------+--------------------------------------------------------+ |
| | 1382 | | 5000 | Pointlike photon-hadron jet production (all flavours) | |
| | 1383 | | 5100+IQ | Pointlike photon heavy flavour IQ pair production | |
| | 1384 | | 5200+IQ | Pointlike photon heavy flavour IQ single excitation | |
| | 1385 | | | After generation, IHPRO is subprocess (see list) | |
| | 1386 | | 5300 | Quark photon Compton scattering | |
| | 1387 | | 5500 | Pointlike photon production of light (u,d,s) L=0 mesons| |
| | 1388 | | 5510,20 | S=0 mesons only, S=1 mesons only (see list for IHPRO) | |
| | 1389 | +---------+--------------------------------------------------------+ |
| | 1390 | | 7000 - | Baryon-number violating and other multi-W processes | |
| | 1391 | | 7999 | generated by HERBVI package | |
| | 1392 | +---------+--------------------------------------------------------+ |
| | 1393 | | 8000 | Minimum bias non-diffractive soft hadron-hadron event | |
| | 1394 | +---------+--------------------------------------------------------+ |
| | 1395 | | 9000 | Deep inelastic lepton scattering (all neutral current) | |
| | 1396 | | 9000+IQ | Deep inelastic lepton scattering (NC on flavour IQ) | |
| | 1397 | | 9010 | Deep inelastic lepton scattering (all charged current) | |
| | 1398 | | 9010+IQ | Deep inelastic lepton scattering (CC on flavour IQ) | |
| | 1399 | +---------+--------------------------------------------------------+ |
| | 1400 | | 9100 | Boson-gluon fusion in NC DIS, all flavours | |
| | 1401 | | 9100+IQ | Boson-gluon fusion in NC DIS, IQ=1-6 as above | |
| | 1402 | | 9107 | J/Psi + gluon production by boson-gluon fusion | |
| | 1403 | | 9110 | QCD Compton process in NC DIS, all flavours | |
| | 1404 | | 9110+IP | QCD Compton process in NC DIS, IP=1-12, d-t, dbar-tbar | |
| | 1405 | | 9130 | All O(alpha-s) NC processes: 9100+9110 | |
| | 1406 | | 9140+IP | CC proc, IP:1 = s cbar,2 = b cbar,3 = s tbar,4 = b tbar| |
| | 1407 | +---------+--------------------------------------------------------+ |
| | 1408 | | 92** | Withdrawn: use 91** instead | |
| | 1409 | +---------+--------------------------------------------------------+ |
| | 1410 | | 9500+ID | W W fusion -> Higgs in e p (ID as in IPROC=300+ID) | |
| | 1411 | +---------+--------------------------------------------------------+ |
| | 1412 | |10000+IP | as IPROC=IP but with soft underlying event (hadron | |
| | 1413 | | | remnant fragmentation in lepton-hadron) suppressed | |
| | 1414 | +---------+--------------------------------------------------------+ |
| | 1415 | |
| | 1416 | The extent to which quark mass effects are included in the hard |
| | 1417 | process cross section is different in different processes. In many |
| | 1418 | processes, they are always treated as massless: IPROC=1300, 1800, |
| | 1419 | 1900, 2100, 2300, 2400, 5300, 9000. In two processes they are all |
| | 1420 | treated as massless except the top quark, for which the mass is |
| | 1421 | correctly incorporated: 1400, 2000. In the case of massless pair |
| | 1422 | production, only quark flavours that are kinematically allowed are |
| | 1423 | produced. In all cases the event kinematics incorporate the quark |
| | 1424 | mass, even when it is not used to calculate the cross section. |
| | 1425 | |
| | 1426 | In two processes, quarks are always treated as massive: 500, 9100. |
| | 1427 | |
| | 1428 | Finally, in several processes, the behaviour is different depending |
| | 1429 | on whether a specific quark flavour is requested, in which case its |
| | 1430 | mass is included, or not, in which case all quarks are treated as |
| | 1431 | massless. These are: IPROC=100, 110, 120, QCD 2->2 scattering |
| | 1432 | (1500 vs 1700+IQ), jets in direct photoproduction (5000 vs 5100+IQ |
| | 1433 | and 5200+IQ). |
| | 1434 | |
| | 1435 | These differences can cause inconsistencies between different ways |
| | 1436 | of generating the same process. The most noticeable example is in |
| | 1437 | direct photoproduction, where one can use process 9130, which uses |
| | 1438 | the exact 2->3 matrix element e+g --> e+q+qbar, or process 5000, |
| | 1439 | which uses the Weizsacker-Williams spectrum for e --> e+gamma and |
| | 1440 | the 2->2 matrix element for gamma+g --> q+qbar. For typical HERA |
| | 1441 | kinematics, the W-W approximation is valid to a few per cent, but |
| | 1442 | the difference between the two processes is much larger, about 20% |
| | 1443 | for PTMIN=2 GeV. This is entirely due to the difference in quark |
| | 1444 | mass treatments, as can be checked by comparing process 9130 with |
| | 1445 | processes 5100+IQ and 5200+IQ summed over IQ |
| | 1446 | ------------------------------------------------------------------------ |
| | 1447 | |
| | 1448 | ****** 6. INPUT PARAMETERS ****** |
| | 1449 | |
| | 1450 | The quantities that may be regarded as adjustable parameters are |
| | 1451 | |
| | 1452 | +----------+----------------------------------+-------+ |
| | 1453 | | Name | Description |Default| |
| | 1454 | +----------+----------------------------------+-------+ |
| | 1455 | | QCDLAM | QCD Lambda (see below) | 0.18 | |
| | 1456 | +----------+----------------------------------+-------+ |
| | 1457 | | RMASS(1) | Down quark mass | 0.32 | |
| | 1458 | | RMASS(2) | Up quark mass | 0.32 | |
| | 1459 | | RMASS(3) | Strange quark mass | 0.50 | |
| | 1460 | | RMASS(4) | Charmed quark mass | 1.55 | |
| | 1461 | | RMASS(5) | Bottom quark mass | 4.95 | |
| | 1462 | | RMASS(6) | Top quark mass | 170. | |
| | 1463 | +----------+----------------------------------+-------+ |
| | 1464 | | RMASS(13)| Gluon effective mass | 0.75 | |
| | 1465 | +----------+----------------------------------+-------+ |
| | 1466 | | VQCUT | Quark virtuality cutoff (added to| 0.48 | |
| | 1467 | | | quark masses in parton showers) | | |
| | 1468 | | VGCUT | Gluon virtuality cutoff (added to| 0.10 | |
| | 1469 | | | effective mass in parton showers)| | |
| | 1470 | | VPCUT | Photon virtuality cutoff | 0.40 | |
| | 1471 | +----------+----------------------------------+-------+ |
| | 1472 | | CLMAX | Maximum cluster mass parameter | 3.35 | |
| | 1473 | | CLPOW | Power in maximum cluster mass | 2.00 | |
| | 1474 | | PSPLT | Split cluster spectrum parameter | 1.00 | |
| | 1475 | +----------+----------------------------------+-------+ |
| | 1476 | | QDIQK | Maximum scale for gluon->diquarks| 0.00 | |
| | 1477 | | PDIQK | Gluon->diquarks rate parameter | 5.00 | |
| | 1478 | +----------+----------------------------------+-------+ |
| | 1479 | | QSPAC | Cutoff for spacelike evolution | 2.50 | |
| | 1480 | | PTRMS | Intrinsic pt in incoming hadrons | 0.00 | |
| | 1481 | +----------+----------------------------------+-------+ |
| | 1482 | |
| | 1483 | Notes on parameters: |
| | 1484 | |
| | 1485 | * QCDLAM can be identified at high momentum fractions (x or z) with |
| | 1486 | the fundamental QCD scale Lambda-MSbar (5 flavours). However, this |
| | 1487 | relation does not necessarily hold in other regions of phase space, |
| | 1488 | since higher order corrections are not treated precisely enough to |
| | 1489 | remove renormalization scheme ambiguities. See S. Catani, G. March- |
| | 1490 | esini and B.R.Webber, Nucl. Phys. B349 (1991) 635. |
| | 1491 | |
| | 1492 | * RMASS(1,2,3,13) are effective light quark and gluon masses used in |
| | 1493 | the hadronization phase of the program. They can be set to zero |
| | 1494 | provided the parton shower cutoffs VQCUT and VGCUT are large enough |
| | 1495 | to prevent divergences (see below). |
| | 1496 | |
| | 1497 | * For cluster hadronization, it must be possible to split gluons into |
| | 1498 | q-qbar, i.e. RMASS(13) must be at least twice the lightest quark |
| | 1499 | mass. Similarly it may be impossible for heavy flavoured clusters |
| | 1500 | to decay if RMASS(4,5) are too low. |
| | 1501 | |
| | 1502 | * VQCUT and VGCUT are needed if the quark and gluon effective masses |
| | 1503 | become small. The condition to avoid divergences in parton showers |
| | 1504 | is |
| | 1505 | 1/Q(i) + 1/Q(j) < 1/QCDL3 for either i or j or both gluons, |
| | 1506 | where Q(i)=RMASS(i)+VQCUT for quarks, RMASS(13)+VGCUT for gluons, |
| | 1507 | and QCDL3 is the equivalent 3-flavour Lambda computed from QCDLAM. |
| | 1508 | In the notation of the above reference by S. Catani et al., QCDL3 |
| | 1509 | is the 3-flavour equivalent of QCDL5 where |
| | 1510 | QCDL5 = QCDLAM*exp(K/(4*pi*beta))/sqrt(2)=1.109*QCDLAM |
| | 1511 | |
| | 1512 | * VPCUT is the analogous quantity for photon emission. It defaults to |
| | 1513 | SQRT(S) corresponding to no emission. Results after experimental |
| | 1514 | cuts are insensitive to its exact value in the range 0.1 to 1.0 GeV |
| | 1515 | |
| | 1516 | * CLMAX and CLPOW determine the maximum allowed mass of a cluster |
| | 1517 | made from quarks i and j as follows |
| | 1518 | Mass**CLPOW < CLMAX**CLPOW + (RMASS(i)+RMASS(j))**CLPOW |
| | 1519 | Since the cluster mass spectrum falls rapidly at high mass, results |
| | 1520 | become insensitive to CLMAX and CLPOW at large values of CLMAX. |
| | 1521 | Smaller values OF CLPOW will increase the yield of heavier clusters |
| | 1522 | (and hence of baryons) for heavy quarks, without affecting light |
| | 1523 | quarks much. For example, the default value gives no b-baryons |
| | 1524 | whereas CLPOW=1.0 makes b-baryons/b-hadrons about 1/4. |
| | 1525 | |
| | 1526 | * PSPLT determines the mass distribution in the cluster splitting |
| | 1527 | CL1 -> CL2 + CL3 when CL1 is above the maximum allowed mass. The |
| | 1528 | masses of CL2 and CL3 are generated uniformly in Mass**PSPLT. Since |
| | 1529 | the number of split clusters is small, dependence on PSPLT is weak. |
| | 1530 | |
| | 1531 | * QDIQK greater than twice the lightest diquark mass enables gluons |
| | 1532 | to split non-perturbatively into diquarks as well as quarks. The |
| | 1533 | probability of this is PDIQK*dQ/Q for scales Q below QDIQK. The |
| | 1534 | diquark masses are taken to be the sum of constituent quark masses. |
| | 1535 | Thus the default value QDIQK=0 suppresses gluon->diquark splitting. |
| | 1536 | |
| | 1537 | * QSPAC is the scale below which the structure functions of incoming |
| | 1538 | hadrons are frozen and non-valence constituent partons are forced |
| | 1539 | to evolve to valence partons, if ISPAC=0. For ISPAC=2, structure |
| | 1540 | functions are frozen at scale QSPAC, but evolution continues down |
| | 1541 | to the infrared cutoff. |
| | 1542 | |
| | 1543 | * PTRMS is the width of the (Gaussian) intrinsic transverse momentum |
| | 1544 | distribution of valence partons in incoming hadrons at scale QSPAC. |
| | 1545 | (N.B. Neither QSPAC nor PTRMS affect lepton-lepton collisions.) |
| | 1546 | |
| | 1547 | In practice, the parameters that have been found most effective in |
| | 1548 | fitting data are QCDLAM, the gluon effective mass RMASS(13), and the |
| | 1549 | cluster mass parameter CLMAX. |
| | 1550 | |
| | 1551 | The default parameter values have been found to give good agreement |
| | 1552 | with event shape distributions at LEP (OPAL preprint CERN-EP/90-48). |
| | 1553 | |
| | 1554 | A number of further parameters are needed to control the program and |
| | 1555 | to turn various options on or off: |
| | 1556 | |
| | 1557 | +----------+----------------------------------+-------+ |
| | 1558 | | Name | Description |Default| |
| | 1559 | +----------+----------------------------------+-------+ |
| | 1560 | | IPRINT | Printout option | 1 | |
| | 1561 | | MAXPR | Number of events to print out | 1 | |
| | 1562 | | PRVTX | Include vertex info in print out | .TRUE.| |
| | 1563 | | MAXER | Max number of errors | 10 | |
| | 1564 | | LWEVT | Unit for writing output events | 0 | |
| | 1565 | | LRSUD | Unit for reading Sudakov table | 0 | |
| | 1566 | | LWSUD | Unit for writing Sudakov table | 77 | |
| | 1567 | | SUDORD | Alpha_s order in Sudakov table | 1 | |
| | 1568 | +----------+----------------------------------+-------+ |
| | 1569 | | NRN(1) | Random number seed 1 | 17673 | |
| | 1570 | | NRN(2) | Random number seed 2 | 63565 | |
| | 1571 | | WGTMAX | Max weight (0 to search for it) | 0. | |
| | 1572 | | NOWGT | Generate unweighted events | .TRUE.| |
| | 1573 | +----------+----------------------------------+-------+ |
| | 1574 | | AZSOFT | Soft gluon azimuthal correlations| .TRUE.| |
| | 1575 | | AZSPIN | Gluon spin azimuthal correlations| .TRUE.| |
| | 1576 | +----------+----------------------------------+-------+ |
| | 1577 | | NCOLO | Number of colours | 3 | |
| | 1578 | | NFLAV | Number of (producible) flavours | 6 | |
| | 1579 | +----------+----------------------------------+-------+ |
| | 1580 | | MODPDF(I)| PDFLIB structure function set and| -1 | |
| | 1581 | | AUTPDF(I)| author group for beam I(=1,2) | 'MRS' | |
| | 1582 | | | (if MODPDF()<0 do not use PDFLIB)| | |
| | 1583 | | NSTRU | Input structure function set | 5 | |
| | 1584 | | | (1,2=Duke-Owens1,2 3,4=EHLQ1,2 | | |
| | 1585 | | | 5=Owens1.1) | | |
| | 1586 | +----------+----------------------------------+-------+ |
| | 1587 | | ETAMIX | eta/eta' mixing angle in degrees | -20 | |
| | 1588 | | | F0Mix.. |
| | 1589 | +----------+----------------------------------+-------+ |
| | 1590 | | B1LIM | B cluster -> 1 hadron parameter | 0.0 | |
| | 1591 | +----------+----------------------------------+-------+ |
| | 1592 | | CLDIR | Decay of perturbative clusters, | 1 | |
| | 1593 | | | 0=>isotropic, 1=>along quark dirn| | |
| | 1594 | | CLSMR | Width of Gaussian angle smearing | 0.0 | |
| | 1595 | +----------+----------------------------------+-------+ |
| | 1596 | | CLRECO | Include colour rearrangement |.FALSE | |
| | 1597 | | PRECO | Probability for rearrangement | 1./9. | |
| | 1598 | | EXAG | Lifetime scaling for weak bosons | 1. | |
| | 1599 | +----------+----------------------------------+-------+ |
| | 1600 | | PIPSMR | Smear the primary vertex | .TRUE.| |
| | 1601 | | MAXDKL | Veto decays outside given volume |.FALSE.| |
| | 1602 | +----------+----------------------------------+-------+ |
| | 1603 | | HARDME | Use hard and soft matrix-element | .TRUE.| |
| | 1604 | | SOFTME | corrections to e+e- and DIS | .TRUE.| |
| | 1605 | +----------+----------------------------------+-------+ |
| | 1606 | | BDECAY | Controls which B Decay package is| 'HERW'| |
| | 1607 | | | used. The allowed values are: | | |
| | 1608 | | | 'HERW'; 'EURO'; or 'CLEO'. | | |
| | 1609 | | MIXING | Include neutral B meson mixing | .TRUE.| |
| | 1610 | | XMIX(2) | Mass difference I=1 B^0_s | 10.0 | |
| | 1611 | | | average width 2 B^0_d | 0.70 | |
| | 1612 | | YMIX(2) | Width difference I=1 B^0_s | 0.20 | |
| | 1613 | | | average width 2 B^0_d | 0.00 | |
| | 1614 | +----------+----------------------------------+-------+ |
| | 1615 | | EPOLN(3) | Electron and positron beam | 0.0 | |
| | 1616 | | | polarizations in DIS and e+e- | 0.0 | |
| | 1617 | | | annihilation. First two cmpts are| 0.0 | |
| | 1618 | | PPOLN(3) | transverse and only used in e+e-,| 0.0 | |
| | 1619 | | | 3rd cmpt is longitudinal, and is | 0.0 | |
| | 1620 | | | +/-1 for fully rh/lh polarized | 0.0 | |
| | 1621 | +----------+----------------------------------+-------+ |
| | 1622 | | BGSHAT | Scale=shat for boson-gluon fusion|.FALSE.| |
| | 1623 | +----------+----------------------------------+-------+ |
| | 1624 | | BREIT | Use Breit frame for DIS kinematix| .TRUE.| |
| | 1625 | +----------+----------------------------------+-------+ |
| | 1626 | | USECMF | Use hadron-hadron cmf | .TRUE.| |
| | 1627 | +----------+----------------------------------+-------+ |
| | 1628 | | NOSPAC | Switch off space-like showers |.FALSE.| |
| | 1629 | +----------+----------------------------------+-------+ |
| | 1630 | | ISPAC | Changes meaning of QSPAC, | 0 | |
| | 1631 | | | see the earlier notes on QSPAC | | |
| | 1632 | +----------+----------------------------------+-------+ |
| | 1633 | | TMNISR | Min vaule shat/S for photon ISR | 1D-4 | |
| | 1634 | | ZMXISR | Max mom fraction for photon ISR | 1-1D-6| |
| | 1635 | +----------+----------------------------------+-------+ |
| | 1636 | | PTMIN | Min pt in hadronic jet production| 10. | |
| | 1637 | | PTMAX | Max pt in hadronic jet production| 1.E8 | |
| | 1638 | | PTPOW | 1/pt**PTPOW for jet sampling | 4. | |
| | 1639 | | YJMIN | Min jet rapidity |-8. | |
| | 1640 | | YJMAX | Max jet rapidity | 8. | |
| | 1641 | +----------+----------------------------------+-------+ |
| | 1642 | | EMMIN | Min dilepton mass in Drell-Yan | 10. | |
| | 1643 | | EMMAX | Max dilepton mass in Drell-Yan | 1.E8 | |
| | 1644 | | EMPOW | 1/m**EMPOW for Drell-Yan sampling| 4. | |
| | 1645 | +----------+----------------------------------+-------+ |
| | 1646 | | Q2MIN | Min Q**2 in deep inelastic | 0.0 | |
| | 1647 | | Q2MAX | Max Q**2 in deep inelastic | 1.E10 | |
| | 1648 | | Q2POW | (1/Q**2)**Q2POW for sampling | 2.5 | |
| | 1649 | +----------+----------------------------------+-------+ |
| | 1650 | | Q2WWMN | Min Q**2 in Equiv Photon Approx | 0.0 | |
| | 1651 | | Q2WWMX | Max Q**2 in Equiv Photon Approx | 4.0 | |
| | 1652 | +----------+----------------------------------+-------+ |
| | 1653 | | YWWMIN | Min energy of gamma in WW approx | 1.0 | |
| | 1654 | | YWWMAX | Max energy of gamma in WW approx | 0.0 | |
| | 1655 | +----------+----------------------------------+-------+ |
| | 1656 | | PHOMAS | Damp structure functions for off-| 0.0 | |
| | 1657 | | | shell photons (0 for no damping) | | |
| | 1658 | +----------+----------------------------------+-------+ |
| | 1659 | | YBMIN | Min and Max Bjorken-y in DIS and | 0.0 | |
| | 1660 | | YBMAX | Equivalent Photon Approx | 1.0 | |
| | 1661 | +----------+----------------------------------+-------+ |
| | 1662 | | ZJMAX | Max Z in J/psi production | 0.9 | |
| | 1663 | +----------+----------------------------------+-------+ |
| | 1664 | | THMAX | Max thrust in 3 parton production| 0.9 | |
| | 1665 | | | (equal to 1-Y_cut in JADE scheme)| | |
| | 1666 | +----------+----------------------------------+-------+ |
| | 1667 | |
| | 1668 | Printout options are: |
| | 1669 | |
| | 1670 | IPRINT = 0 Print program title only |
| | 1671 | 1 Print selected input parameters |
| | 1672 | 2 1 + table of particle codes and properties |
| | 1673 | 3 2 + tables of Sudakov form factors |
| | 1674 | |
| | 1675 | PRVTX = .T. To include the production vertex information in |
| | 1676 | the event print out, requires wide screen format. |
| | 1677 | |
| | 1678 | See sect. 8 on form factors for details of LRSUD, LWSUD and SUDORD. |
| | 1679 | |
| | 1680 | If BGSHAT is false, the scale used for heavy quark production via |
| | 1681 | boson-gluon fusion in lepton-hadron collisions will be |
| | 1682 | 2*shat*that*uhat/(shat**2+that**2+uhat**2) |
| | 1683 | |
| | 1684 | If BREIT is true, the kinematic reconstruction of deep inelastic |
| | 1685 | events takes place in the Breit frame (ie. the frame where the |
| | 1686 | exchanged boson is purely space-like, and collinear with the |
| | 1687 | incoming hadron). In fact the reconstruction procedure is |
| | 1688 | invariant under longitudinal boosts, so any frame in which the |
| | 1689 | boson and hadron are collinear would be equivalent, and it is only |
| | 1690 | the transverse part of the boost that has an effect. |
| | 1691 | The BREIT frame option becomes very inaccurate for very small Q^2. |
| | 1692 | It is therefore only used if Q**2 > 1E-4 (the lab and Breit frames |
| | 1693 | are anyway equivalent for such small Q**2). |
| | 1694 | If BREIT is false, reconstruction takes place in the lab frame. |
| | 1695 | |
| | 1696 | If USECMF is true, the entire event record is boost to the hadron- |
| | 1697 | hadron cmf before event processing, and boosted back afterwards. |
| | 1698 | This means that fixed-target simulation can be done in the lab |
| | 1699 | frame, ie with PBEAM2=0. |
| | 1700 | For hadronic processes with lepton beams, this boosting is always |
| | 1701 | done, regardless of the value of USECMF. |
| | 1702 | |
| | 1703 | The interface to the PDFLIB structure function package is |
| | 1704 | compatible with PDFLIB versions 3 and 4. For version 4, AUTPDF() |
| | 1705 | should be set to the author group as listed in the PDFLIB manual, |
| | 1706 | eg 'MRS', and MODPDF() to the set number in the new convention. |
| | 1707 | For version 3, AUTPDF() should be set to 'MODE', and MODPDF() to |
| | 1708 | the set number in the old convention. |
| | 1709 | |
| | 1710 | The `hard' matrix-element correction adds e+e- and DIS events in |
| | 1711 | regions of phase-space that cannot be filled by the usual parton |
| | 1712 | shower. The `soft' matrix-element correction moves emissions |
| | 1713 | around within the shower phase-space, essentially by matching |
| | 1714 | the HARDEST emission (which is not necessarily the first) to the |
| | 1715 | first-order matrix-element. |
| | 1716 | |
| | 1717 | The quantities from PTMIN onwards control the region of phase |
| | 1718 | space in which events are generated and the importance sampling |
| | 1719 | inside those regions. See section 11 on event weights for further |
| | 1720 | details on these quantities and the use of WGTMAX and NOWGT. |
| | 1721 | |
| | 1722 | If hadronic processes with lepton beams are requested, the photon |
| | 1723 | emission vertex includes the full transverse-momentum-dependent |
| | 1724 | kinematics (the Equivalent Photon Approximation). The variables |
| | 1725 | Q2WWMN and Q2WWMX set the minimum and maximum virtualities |
| | 1726 | generated respectively. For normal simulation, Q2WWMN should be 0, |
| | 1727 | and Q2WWMX should be the largest Q**2 through which the lepton can |
| | 1728 | be scattered without being detected. The variables YBMIN and |
| | 1729 | YBMAX control the range of lightcone momentum fraction generated. |
| | 1730 | |
| | 1731 | In addition there are options to give different weights to the |
| | 1732 | various flavours of quarks and diquarks, and to resonances of |
| | 1733 | different spins. So far, these options have not been used. See |
| | 1734 | the comments in the initialization routine HWIGIN for details. |
| | 1735 | |
| | 1736 | ------------------------------------------------------------------------ |
| | 1737 | |
| | 1738 | ****** 7. COMMON BLOCK FILE ****** |
| | 1739 | |
| | 1740 | C ****COMMON BLOCK FILE FOR HERWIG VERSION 5.9**** |
| | 1741 | C |
| | 1742 | C ALTERATIONS: See 5.8 for list of previous revisions |
| | 1743 | C Layout completely overhauled |
| | 1744 | C |
| | 1745 | C The following variables have been removed: |
| | 1746 | C FBTM,FTOP,FHVY,VECWT,TENWT,SWT,RESWT |
| | 1747 | C MADDR,MODES,MODEF,IDPRO |
| | 1748 | C The following COMMON BLOCK has been removed |
| | 1749 | C /HWUFHV/ - BDECAY moved to /HWPRCH/ |
| | 1750 | C The following COMMON BLOCKs have been added |
| | 1751 | C /HWBMCH/ -contains PART1, PART2 from /HWBEAM/ |
| | 1752 | C /HWPRCH/ -contains AUTPDF from /HWPARM/ & BDECAY |
| | 1753 | C /HWPROP/ -contains many variables from /HWUPDT/ |
| | 1754 | C /HWDIST/ -contains variables for mixing and vertices |
| | 1755 | C /HWQDKS/ -contains heavy flavour decay information |
| | 1756 | C The following variables have been changed to CHARACTER*8: |
| | 1757 | C PART1,PART2,RNAME |
| | 1758 | C The following parameters have been added: |
| | 1759 | C NMXCDK,NMXDKS,NMXMOD,NMXQDK,NMXRES |
| | 1760 | C The following variables have been added: |
| | 1761 | C CSPEED,F0MIX,F1MIX,F2MIX,H1MIX, |
| | 1762 | C PHIMIX,IOPREM,PRVTX see HWPRAM |
| | 1763 | C ANOMSC,ISLENT see HWBRCH |
| | 1764 | C GAMWT see HWEVNT |
| | 1765 | C ASFIXD,OMEGA0,TMNISR,WHMIN,YWWMAX, |
| | 1766 | C YWWMIN,ZMXISR,COLISR see HWHARD |
| | 1767 | C IFLAV,RLTIM,RSPIN,VTOCDK,VTORDK see HWPROP |
| | 1768 | C DKLTM,IDK,IDKPRD,LNEXT,LSTRT, |
| | 1769 | C NDKYS,NME,NMODES,NPRODS, |
| | 1770 | C DKPSET,RSTAB see HWUPDT |
| | 1771 | C REPWT,SNGWT see HWUWTS |
| | 1772 | C CLDKWT,CTHRPW,PRECO,NCLDK,CLRECO see HWUCLU |
| | 1773 | C EXAG,GEV2MM,HBAR,PLTCUT,VMIN2, |
| | 1774 | C VTXPIP,XMIX,XMRCT,YMIX,YMRCT, |
| | 1775 | C IOPDKL,MAXDKL,MIXING,PIPSMR see HWDIST |
| | 1776 | C VTXQDK,IMQDK,LOCQ,NQDK see HWQDKS |
| | 1777 | C |
| | 1778 | C |
| | 1779 | IMPLICIT NONE |
| | 1780 | DOUBLE PRECISION ZERO,ONE,TWO,THREE,FOUR,HALF |
| | 1781 | PARAMETER (ZERO =0.D0, ONE =1.D0, TWO =2.D0, |
| | 1782 | & THREE=3.D0, FOUR=4.D0, HALF=0.5D0) |
| | 1783 | C |
| | 1784 | DOUBLE PRECISION |
| | 1785 | & ACCUR,AFCH,ALPFAC,ALPHEM,ANOMSC,ASFIXD,AVWGT,B1LIM,BETAF,BRFRAC, |
| | 1786 | & BRHIG,BTCLM,CAFAC,CFFAC,CLDKWT,CLMAX,CLPOW,CLQ,CLSMR,CMMOM,COSS, |
| | 1787 | & COSTH,CSPEED,CTHRPW,CTMAX,DECPAR,DECWT,DISF,DKLTM,EBEAM1,EBEAM2, |
| | 1788 | & EMLST,EMMAX,EMMIN,EMPOW,EMSCA,ENHANC,ENSOF,EPOLN,ETAMIX,EVWGT, |
| | 1789 | & EXAG,F0MIX,F1MIX,F2MIX,GAMH,GAMMAX,GAMW,GAMWT,GAMZ,GAMZP,GCOEF, |
| | 1790 | & GEV2NB,GEV2MM,GPOLN,H1MIX,HBAR,HARDST,OMEGA0,PBEAM1,PBEAM2,PDIQK, |
| | 1791 | & PGSMX,PGSPL,PHEP,PHIMIX,PHIPAR,PHOMAS,PIFAC,PLTCUT,PPAR,PPOLN, |
| | 1792 | & PRECO,PRSOF,PSPLT,PTINT,PTMAX,PTMIN,PTPOW,PTRMS,PXRMS,PWT,Q2MAX, |
| | 1793 | & Q2MIN,Q2POW,Q2WWMN,Q2WWMX,QCDL3,QCDL5,QCDLAM,QDIQK,QEV,QFCH,QG, |
| | 1794 | & QLIM,QSPAC,QV,QWT,REPWT,RESN,RHOHEP,RHOPAR,RLTIM,RMASS,RMIN, |
| | 1795 | & RSPIN,SCABI,SINS,SNGWT,SWEIN,SWTEF,SUD,THMAX,TLOUT,TMTOP,TMNISR, |
| | 1796 | & TQWT,VCKM,VFCH,VGCUT,VHEP,VMIN2,VPAR,VPCUT,VQCUT,VTXPIP,VTXQDK, |
| | 1797 | & WBIGST,WGTMAX,WGTSUM,WHMIN,WSQSUM,XFACT,XLMIN,XMIX,XMRCT,XX, |
| | 1798 | & XXMIN,YBMAX,YBMIN,YJMAX,YJMIN,YMIX,YMRCT,YWWMAX,YWWMIN,ZBINM, |
| | 1799 | & ZJMAX,ZMXISR |
| | 1800 | C |
| | 1801 | INTEGER |
| | 1802 | & CLDIR,IAPHIG,IBRN,IBSH,ICHRG,ICO,IDCMF,IDHEP,IDHW,IDK,IDKPRD,IDN, |
| | 1803 | & IDPAR,IDPDG,IERROR,IFLAV,IFLMAX,IFLMIN,IHPRO,IMQDK,INHAD,INTER, |
| | 1804 | & IOPDKL,IOPHIG,IOPREM,IPART1,IPART2,IPRINT,IPRO,IPROC,ISLENT, |
| | 1805 | & ISPAC,ISTAT,ISTHEP,ISTPAR,JCOPAR,JDAHEP,JDAPAR,JMOHEP,JMOPAR, |
| | 1806 | & JNHAD,LNEXT,LOCN,LOCQ,LRSUD,LSTRT,LWEVT,LWSUD,MAPQ,MAXER,MAXEV, |
| | 1807 | & MAXFL,MAXPR,MODBOS,MODMAX,MODPDF,NBTRY,NCLDK,NCOLO,NCTRY,NDKYS, |
| | 1808 | & NDTRY,NETRY,NEVHEP,NEVPAR,NFLAV,NGSPL,NHEP,NME,NMODES,NMXCDK, |
| | 1809 | & NMXDKS,NMXHEP,NMXJET,NMXMOD,NMXPAR,NMXQDK,NMXRES,NMXSUD,NPAR, |
| | 1810 | & NPRODS,NQDK,NQEV,NRES,NRN,NSPAC,NSTRU,NSTRY,NSUD,NUMER,NUMERU, |
| | 1811 | & NWGTS,NZBIN,SUDORD |
| | 1812 | C |
| | 1813 | LOGICAL |
| | 1814 | & AZSOFT,AZSPIN,BGSHAT,BREIT,CLRECO,COLISR,DKPSET,FROST,FSTEVT, |
| | 1815 | & FSTWGT,GENEV,GENSOF,HARDME,HVFCEN,MAXDKL,MIXING,NOSPAC,NOWGT, |
| | 1816 | & PRNDEC,PIPSMR,PRVTX,RSTAB,SOFTME,TMPAR,TPOL,USECMF,VTOCDK,VTORDK, |
| | 1817 | & ZPRIME |
| | 1818 | C |
| | 1819 | CHARACTER*4 |
| | 1820 | & BDECAY |
| | 1821 | CHARACTER*8 |
| | 1822 | & PART1,PART2,RNAME |
| | 1823 | CHARACTER*20 |
| | 1824 | & AUTPDF |
| | 1825 | C |
| | 1826 | C New standard event common |
| | 1827 | PARAMETER (NMXHEP=2000) |
| | 1828 | COMMON/HEPEVT/NEVHEP,NHEP,ISTHEP(NMXHEP),IDHEP(NMXHEP), |
| | 1829 | & JMOHEP(2,NMXHEP),JDAHEP(2,NMXHEP),PHEP(5,NMXHEP),VHEP(4,NMXHEP) |
| | 1830 | C |
| | 1831 | C Beams, process and number of events |
| | 1832 | COMMON/HWBEAM/IPART1,IPART2 |
| | 1833 | COMMON/HWBMCH/PART1,PART2 |
| | 1834 | COMMON/HWPROC/EBEAM1,EBEAM2,PBEAM1,PBEAM2,IPROC,MAXEV |
| | 1835 | C |
| | 1836 | C Basic parameters (and quantities derived from them) |
| | 1837 | COMMON/HWPRAM/AFCH(16,2),ALPHEM,B1LIM,BETAF,BTCLM,CAFAC,CFFAC, |
| | 1838 | & CLMAX,CLPOW,CLSMR,CSPEED,ENSOF,ETAMIX,F0MIX,F1MIX,F2MIX,GAMH, |
| | 1839 | & GAMW,GAMZ,GAMZP,GEV2NB,H1MIX,PDIQK,PGSMX,PGSPL(4),PHIMIX,PIFAC, |
| | 1840 | & PRSOF,PSPLT,PTRMS,PXRMS,QCDL3,QCDL5,QCDLAM,QDIQK,QFCH(16),QG, |
| | 1841 | & QSPAC,QV,SCABI,SWEIN,TMTOP,VFCH(16,2),VCKM(3,3),VGCUT,VQCUT, |
| | 1842 | & VPCUT,ZBINM,IOPREM,IPRINT,ISPAC,LRSUD,LWSUD,MODPDF(2),NBTRY, |
| | 1843 | & NCOLO,NCTRY,NDTRY,NETRY,NFLAV,NGSPL,NSTRU,NSTRY,NZBIN,AZSOFT, |
| | 1844 | & AZSPIN,CLDIR,HARDME,NOSPAC,PRNDEC,PRVTX,SOFTME,ZPRIME |
| | 1845 | C |
| | 1846 | COMMON/HWPRCH/AUTPDF(2),BDECAY |
| | 1847 | C |
| | 1848 | C Parton shower common (same format as /HEPEVT/) |
| | 1849 | PARAMETER (NMXPAR=500) |
| | 1850 | COMMON/HWPART/NEVPAR,NPAR,ISTPAR(NMXPAR),IDPAR(NMXPAR), |
| | 1851 | & JMOPAR(2,NMXPAR),JDAPAR(2,NMXPAR),PPAR(5,NMXPAR),VPAR(4,NMXPAR) |
| | 1852 | C |
| | 1853 | C Parton polarization common |
| | 1854 | COMMON/HWPARP/DECPAR(2,NMXPAR),PHIPAR(2,NMXPAR),RHOPAR(2,NMXPAR), |
| | 1855 | & TMPAR(NMXPAR) |
| | 1856 | C |
| | 1857 | C Electroweak boson common |
| | 1858 | PARAMETER (MODMAX=5) |
| | 1859 | COMMON/HWBOSC/ALPFAC,BRHIG(12),ENHANC(12),GAMMAX,RHOHEP(3,NMXHEP), |
| | 1860 | & IOPHIG,MODBOS(MODMAX) |
| | 1861 | C |
| | 1862 | C Parton colour common |
| | 1863 | COMMON/HWPARC/JCOPAR(4,NMXPAR) |
| | 1864 | C |
| | 1865 | C other HERWIG branching, event and hard subprocess common blocks |
| | 1866 | COMMON/HWBRCH/ANOMSC(2,2),HARDST,PTINT(3,2),XFACT,INHAD,JNHAD, |
| | 1867 | & NSPAC(7),ISLENT,BREIT,FROST,USECMF |
| | 1868 | C |
| | 1869 | COMMON/HWEVNT/AVWGT,EVWGT,GAMWT,TLOUT,WBIGST,WGTMAX,WGTSUM,WSQSUM, |
| | 1870 | & IDHW(NMXHEP),IERROR,ISTAT,LWEVT,MAXER,MAXPR,NOWGT,NRN(2),NUMER, |
| | 1871 | & NUMERU,NWGTS,GENSOF |
| | 1872 | C |
| | 1873 | COMMON/HWHARD/ASFIXD,CLQ(7,6),COSS,COSTH,CTMAX,DISF(13,2),EMLST, |
| | 1874 | & EMMAX,EMMIN,EMPOW,EMSCA,EPOLN(3),GCOEF(7),GPOLN,OMEGA0,PHOMAS, |
| | 1875 | & PPOLN(3),PTMAX,PTMIN,PTPOW,Q2MAX,Q2MIN,Q2POW,Q2WWMN,Q2WWMX,QLIM, |
| | 1876 | & SINS,THMAX,TMNISR,TQWT,XX(2),XLMIN,XXMIN,YBMAX,YBMIN,YJMAX, |
| | 1877 | & YJMIN,YWWMAX,YWWMIN,WHMIN,ZJMAX,ZMXISR,IAPHIG,IBRN(2),IBSH, |
| | 1878 | & ICO(10),IDCMF,IDN(10),IFLMAX,IFLMIN,IHPRO,IPRO,MAPQ(6),MAXFL, |
| | 1879 | & BGSHAT,COLISR,FSTEVT,FSTWGT,GENEV,HVFCEN,TPOL |
| | 1880 | C |
| | 1881 | C Arrays for particle properties (NMXRES = max no of particles defined) |
| | 1882 | PARAMETER(NMXRES=400) |
| | 1883 | COMMON/HWPROP/RLTIM(0:NMXRES),RMASS(0:NMXRES),RSPIN(0:NMXRES), |
| | 1884 | & ICHRG(0:NMXRES),IDPDG(0:NMXRES),IFLAV(0:NMXRES),NRES, |
| | 1885 | & VTOCDK(0:NMXRES),VTORDK(0:NMXRES) |
| | 1886 | C |
| | 1887 | COMMON/HWUNAM/RNAME(0:NMXRES) |
| | 1888 | C |
| | 1889 | C Arrays for particle decays (NMXDKS = max total no of decays, |
| | 1890 | C NMXMOD = max no of modes for a particle) |
| | 1891 | PARAMETER(NMXDKS=4000,NMXMOD=200) |
| | 1892 | COMMON/HWUPDT/BRFRAC(NMXDKS),CMMOM(NMXDKS),DKLTM(NMXRES), |
| | 1893 | & IDK(NMXDKS),IDKPRD(5,NMXDKS),LNEXT(NMXDKS),LSTRT(NMXRES),NDKYS, |
| | 1894 | & NME(NMXDKS),NMODES(NMXRES),NPRODS(NMXDKS),DKPSET,RSTAB(0:NMXRES) |
| | 1895 | C |
| | 1896 | C Weights used in cluster decays |
| | 1897 | COMMON/HWUWTS/REPWT(0:3,0:4,0:4),SNGWT,DECWT,QWT(3),PWT(12), |
| | 1898 | & SWTEF(NMXRES) |
| | 1899 | C |
| | 1900 | C Parameters for cluster decays (NMXCDK = max total no of cluster |
| | 1901 | C decay channels) |
| | 1902 | PARAMETER(NMXCDK=4000) |
| | 1903 | COMMON/HWUCLU/CLDKWT(NMXCDK),CTHRPW(12,12),PRECO,RESN(12,12), |
| | 1904 | & RMIN(12,12),LOCN(12,12),NCLDK(NMXCDK),CLRECO |
| | 1905 | C |
| | 1906 | C Variables controling mixing and vertex information |
| | 1907 | COMMON/HWDIST/EXAG,GEV2MM,HBAR,PLTCUT,VMIN2,VTXPIP(4),XMIX(2), |
| | 1908 | & XMRCT(2),YMIX(2),YMRCT(2),IOPDKL,MAXDKL,MIXING,PIPSMR |
| | 1909 | C |
| | 1910 | C Arrays for temporarily storing heavy-b,c-hadrons decaying partonicaly |
| | 1911 | C (NMXBDK = max no such b-hadron decays in an event) |
| | 1912 | PARAMETER (NMXQDK=20) |
| | 1913 | COMMON/HWQDKS/VTXQDK(4,NMXQDK),IMQDK(NMXQDK),LOCQ(NMXQDK),NQDK |
| | 1914 | C |
| | 1915 | C Parameters for Sudakov form factors |
| | 1916 | C (NMXSUD= max no of entries in lookup table) |
| | 1917 | PARAMETER (NMXSUD=1024) |
| | 1918 | COMMON/HWUSUD/ACCUR,QEV(NMXSUD,6),SUD(NMXSUD,6),INTER,NQEV,NSUD, |
| | 1919 | & SUDORD |
| | 1920 | C |
| | 1921 | PARAMETER (NMXJET=200) |
| | 1922 | ------------------------------------------------------------------------ |
| | 1923 | |
| | 1924 | ****** 8. FORM FACTOR FILE ****** |
| | 1925 | |
| | 1926 | HERWIG uses look-up tables of Sudakov form factors for the evolution |
| | 1927 | of initial- and final-state parton showers. These can be read from |
| | 1928 | an input file rather than being recomputed each time. The reading, |
| | 1929 | writing and computing of form factor tables is controlled by integer |
| | 1930 | parameters LRSUD and LWSUD: |
| | 1931 | |
| | 1932 | LRSUD = N>0 Read form factors for this run from unit N |
| | 1933 | LRSUD = 0 Compute new form factor tables for this run |
| | 1934 | LRSUD < 0 Form factor tables are already loaded |
| | 1935 | LWSUD = N>0 Write form factors on unit N for future use |
| | 1936 | LWSUD = 0 Do not write new form factor tables |
| | 1937 | |
| | 1938 | The option LRSUD<0 allows the program to be initialized several times |
| | 1939 | in the same run (e.g. to generate various event types) without recom- |
| | 1940 | puting or rereading form factors. |
| | 1941 | |
| | 1942 | N.B. The Sudakov form factors depend on the parameters QCDLAM, VQCUT, |
| | 1943 | VGCUT, NCOLO, NFLAV, NAFLA, RMASS(13) and RMASS(i) for i=1,...,NFLAV. |
| | 1944 | Consequently form factor tables MUST be recomputed every time any of |
| | 1945 | these parameters is changed. From version 5.1 onwards, these |
| | 1946 | parameters are written/read with the form factor tables and checks |
| | 1947 | are performed to ensure consistency. |
| | 1948 | |
| | 1949 | The parton showering algorithm uses the two-loop alpha_s, with |
| | 1950 | matching at each flavour threshold. However, the Sudakov table can be |
| | 1951 | computed with either the one-loop or two-loop form, according to the |
| | 1952 | variable SUDORD (= 1 or 2 respectively, DEFAULT=1). If SUDORD=1 the |
| | 1953 | two-loop value is recovered using the veto algorithm in the shower, |
| | 1954 | whereas if SUDORD=2 no vetoes are used in the final-state evolution. |
| | 1955 | This means that the relative weight of any shower configuration can |
| | 1956 | be calculated in a closed form, hence that showers can be `forced'. |
| | 1957 | |
| | 1958 | To next-to-leading order the two possibilities should be identical, |
| | 1959 | but they differ at beyond-NLO, so some results may change a little. |
| | 1960 | The most noticeable difference is that the form factor table takes a |
| | 1961 | factor of about five times longer to compute with SUDORD=2 than 1. |
| | 1962 | ------------------------------------------------------------------------ |
| | 1963 | |
| | 1964 | ****** 9. EVENT DATA ****** |
| | 1965 | |
| | 1966 | /HEPEVT/ is the standard common block containing current event data: |
| | 1967 | |
| | 1968 | NEVHEP - event number |
| | 1969 | NHEP - number of entries for this event |
| | 1970 | ISTHEP(I) - status of entry I (see below) |
| | 1971 | IDHEP(I) - identity of entry I (revised Particle Data Group code) |
| | 1972 | JMOHEP(1,I) - pointer to first mother of entry I (see below) |
| | 1973 | JMOHEP(2,I) - pointer to second mother of entry I (see below) |
| | 1974 | JDAHEP(1,I) - pointer to first daughter of entry I (see below) |
| | 1975 | JDAHEP(2,I) - pointer to last daughter of entry I (see below) |
| | 1976 | PHEP(*,I) - (Px,Py,Pz,E,M) of entry I: M=sign(sqrt(abs(m**2)),m**2) |
| | 1977 | VHEP(*,I) - (x,y,z,t) of prod'n vertex of entry I (see section 13) |
| | 1978 | |
| | 1979 | All momenta are given in the laboratory frame, in which the input |
| | 1980 | beam momenta are PBEAM1 and PBEAM2 as specified by the user and point |
| | 1981 | along the +z and -z directions respectively. Final state particles |
| | 1982 | have ISTHEP(I) = 1. See the next section for a complete list of the |
| | 1983 | special status codes used by HERWIG. |
| | 1984 | |
| | 1985 | The identity codes IDHEP are as those suggested by the LEP II Working |
| | 1986 | group i.e. the revised Particle Data Group numbers plus the following |
| | 1987 | |
| | 1988 | * IDHEP = 91 for clusters, 94 for jets, 0 for others with no PDG code. |
| | 1989 | |
| | 1990 | (HERWIG also has its own internal identity codes IDHW(I), stored in |
| | 1991 | /HWEVNT/. The utility subroutine HWUIDT translates between HERWIG and |
| | 1992 | PDG identity codes. See section 20 for further details.) |
| | 1993 | |
| | 1994 | The mother/daughter pointers are standard, except that JMOHEP(2,I) |
| | 1995 | and JDAHEP(2,I) for a PARTON are its COLOUR mother and daughter, |
| | 1996 | i.e., the partons to which its colour and anticolour are connected, |
| | 1997 | respectively. For this purpose the primary partons from a hard sub- |
| | 1998 | process are all regarded as outgoing (see examples in sects. 15, 19 |
| | 1999 | and 21). Since quarks have no anticolour, JDAHEP(2,I) is used to |
| | 2000 | point to its FLAVOUR partner. Similarly for JMOHEP(2,I) in the case |
| | 2001 | of an antiquark. |
| | 2002 | |
| | 2003 | In addition to entries representing partons, particles, clusters etc, |
| | 2004 | /HEPEVT/ contains purely informational entries representing the total |
| | 2005 | c.m. momentum, hard and soft subprocess momenta, etc. See section 10 |
| | 2006 | for the corresponding status codes. |
| | 2007 | |
| | 2008 | Information from all stages of event processing is retained in |
| | 2009 | /HEPEVT/ so the same particle may appear several times with different |
| | 2010 | status codes. For example, an outgoing parton from a hard scattering |
| | 2011 | (entered initially with status 113 or 114) will appear after process- |
| | 2012 | ing as an on-mass-shell parton before QCD branching (status 123,124), |
| | 2013 | an off-mass-shell entry representing the flavour and momentum of the |
| | 2014 | outgoing jet (status 143,144), and a jet constituent (157). It might |
| | 2015 | also appear again in other contexts, e.g. as a spectator in a heavy |
| | 2016 | flavour decay (status 154,160). |
| | 2017 | |
| | 2018 | Incoming partons (entered with status 111, 112, changed to 121, 122 |
| | 2019 | after branching) give rise to spacelike jets (status 141,142, m**2<0, |
| | 2020 | indicated by PHEP(5,IHEP)<0) due to the loss of momentum via initial |
| | 2021 | state bremsstrahlung. The same applies in principle to incoming |
| | 2022 | leptons, but QED radiative corrections are not yet included. |
| | 2023 | |
| | 2024 | Each parton jet begins with a status 141-144 jet entry giving the |
| | 2025 | total flavour and momentum of the jet. The first mother pointer of |
| | 2026 | this entry gives the location of the parent hard parton, while the |
| | 2027 | second gives that of the subprocess c.m. momentum. If QCD branching |
| | 2028 | has occurred, this is followed by a lightlike CONE entry, which |
| | 2029 | fixes the angular extent of the jet and its azimuthal orientation |
| | 2030 | relative to the parton with which it interferes. The interfering par- |
| | 2031 | ton is listed as the second mother of the cone. Next come the actual |
| | 2032 | constituents of the jet. If no branching has occurred, there is no |
| | 2033 | cone and the single jet constituent is the same as the jet. |
| | 2034 | ------------------------------------------------------------------------ |
| | 2035 | |
| | 2036 | ****** 10. STATUS CODES ****** |
| | 2037 | |
| | 2038 | A complete list of currently-used HERWIG status codes is given below. |
| | 2039 | Many are used only in intermediate stages of event processing. The |
| | 2040 | most important for users are probably 1 (final-state particle), 101-3 |
| | 2041 | (initial state), 141-4 (jets), and 199 (decayed b- and t-flavoured |
| | 2042 | hadrons). |
| | 2043 | |
| | 2044 | The event status ISTAT in common /HWEVNT/ is roughly ISTHEP-100 where |
| | 2045 | ISTHEP is the status of entries being processed. However, ISTAT=100 |
| | 2046 | for completed events. |
| | 2047 | |
| | 2048 | +------+-------------------------------------------+ |
| | 2049 | |ISTHEP| Description | |
| | 2050 | +------+-------------------------------------------+ |
| | 2051 | | 1 | final state particle | |
| | 2052 | | 2 | parton before hadronization | |
| | 2053 | | 3 | documentation line | |
| | 2054 | +------+-------------------------------------------+ |
| | 2055 | | 100 | cone limiting jet evolution | |
| | 2056 | | 101 | `beam' (beam 1) | |
| | 2057 | | 102 | `target' (beam 2) | |
| | 2058 | | 103 | overall centre of mass | |
| | 2059 | +------+-------------------------------------------+ |
| | 2060 | | 110 | unprocessed hard process CoM | |
| | 2061 | | 111 | " beam parton | |
| | 2062 | | 112 | " target " | |
| | 2063 | | 113 | " outgoing " 3 | |
| | 2064 | | 114 | " outgoing " 4 | |
| | 2065 | | 115 | " spectator " | |
| | 2066 | +------+-------------------------------------------+ |
| | 2067 | |120-25| as 110-15, after processing | |
| | 2068 | +------+-------------------------------------------+ |
| | 2069 | | 130 | lepton in jet (unboosted) | |
| | 2070 | |131-34| as 141-44, unboosted to CoM | |
| | 2071 | | 135 | spacelike parton (beam, unboosted) | |
| | 2072 | | 136 | " " (target, " ) | |
| | 2073 | | 137 | spectator (beam, unboosted) | |
| | 2074 | | 138 | " (target, " ) | |
| | 2075 | | 139 | parton from branching (unboosted) | |
| | 2076 | | 140 | " " g splitting ( " ) | |
| | 2077 | +------+-------------------------------------------+ |
| | 2078 | |141-44| jet from parton type 111-14 | |
| | 2079 | |145-50| as 135-40 boosted, unclustered | |
| | 2080 | +------+-------------------------------------------+ |
| | 2081 | | 151 | as 159, not yet clustered | |
| | 2082 | | 152 | as 160, " " " | |
| | 2083 | | 153 | spectator from beam | |
| | 2084 | | 154 | " " target | |
| | 2085 | | 155 | heavy quark before decay | |
| | 2086 | | 156 | spectator before heavy decay | |
| | 2087 | | 157 | parton from QCD branching | |
| | 2088 | | 158 | " after gluon splitting | |
| | 2089 | | 159 | " from cluster splitting | |
| | 2090 | | 160 | spectator after heavy decay | |
| | 2091 | +------+-------------------------------------------+ |
| | 2092 | | 161 | beam spectator after gluon splitting | |
| | 2093 | | 162 | target " " " " | |
| | 2094 | | 163 | other cluster before soft process | |
| | 2095 | | 164 | beam " " " " | |
| | 2096 | | 165 | target " " " " | |
| | 2097 | | 167 | unhadronized beam cluster | |
| | 2098 | | 168 | unhadronized target cluster | |
| | 2099 | +------+-------------------------------------------+ |
| | 2100 | | 170 | soft process centre of mass | |
| | 2101 | | 171 | soft cluster (beam, unhadronized) | |
| | 2102 | | 172 | soft cluster (target, " ) | |
| | 2103 | | 173 | soft cluster (other, " ) | |
| | 2104 | +------+-------------------------------------------+ |
| | 2105 | | 181 | beam cluster (no soft process) | |
| | 2106 | | 182 | target " ( " " " ) | |
| | 2107 | | 183 | hard process " (hadronized) | |
| | 2108 | | 184 | soft " (beam, hadronized) | |
| | 2109 | | 185 | " " (target, " ) | |
| | 2110 | | 186 | " " (other, " ) | |
| | 2111 | +------+-------------------------------------------+ |
| | 2112 | |190-93| as 195-98, before decays | |
| | 2113 | | 195 | direct unstable non-hadron | |
| | 2114 | | 196 | " " hadron (1-body cluster) | |
| | 2115 | | 197 | " " " (2-body cluster) | |
| | 2116 | | 198 | indirect unstable hadron or lepton | |
| | 2117 | | 199 | decayed heavy flavour hadron | |
| | 2118 | +------+-------------------------------------------+ |
| | 2119 | | 200 | neutral B meson, flavour at production | |
| | 2120 | +------+-------------------------------------------+ |
| | 2121 | ------------------------------------------------------------------------ |
| | 2122 | |
| | 2123 | ****** 11. EVENT WEIGHTS ****** |
| | 2124 | |
| | 2125 | The default is to generate unweighted events (EVWGT=AVWGT). Then |
| | 2126 | event distributions are generated by computing a weight proportional |
| | 2127 | to the cross section and comparing it with a random number times the |
| | 2128 | maximum weight. Set WGTMAX to the maximum weight, or to zero for the |
| | 2129 | program to compute it. If a weight greater than WGTMAX is generated |
| | 2130 | during execution, a warning is printed and WGTMAX is reset. Similarly |
| | 2131 | if the efficiency is too low (WGTMAX too large). If these errors |
| | 2132 | occur too often, output event distributions could be distorted. |
| | 2133 | |
| | 2134 | To generate weighted events, set NOWGT=.FALSE. in common /HWEVNT/. |
| | 2135 | |
| | 2136 | In QCD hard scattering and heavy flavour and direct photon production |
| | 2137 | (IPROC = 1500 to 1800) the transverse energy distribution of weighted |
| | 2138 | events (or the efficiency for unweighted events) can be varied using |
| | 2139 | the parameters PTMIN, PTMAX and PTPOW. |
| | 2140 | |
| | 2141 | Similarly in Drell-Yan processes (IPROC = 13**) the lepton pair mass |
| | 2142 | distribution is controlled by the parameters EMMIN, EMMAX and EMPOW, |
| | 2143 | and in deep inelastic scattering the Q**2 distribution is set by |
| | 2144 | Q2MIN, Q2MAX and Q2POW. |
| | 2145 | |
| | 2146 | Data on weights generated are output at the end of the run. The mean |
| | 2147 | weight is an estimate of the cross section (in nanobarns) integrated |
| | 2148 | over the region used for event generation. |
| | 2149 | |
| | 2150 | N.B. The mean weight is the sum of weights divided by the total |
| | 2151 | number of WEIGHTS generated, not the total number of EVENTS. |
| | 2152 | ------------------------------------------------------------------------ |
| | 2153 | |
| | 2154 | ****** 12. HEAVY FLAVOUR DECAYS ****** |
| | 2155 | |
| | 2156 | Heavy quark decays are treated as secondary hard subprocesses. Top |
| | 2157 | quarks can decay either before or after hadronization, depending on |
| | 2158 | the value of the logical variable DECAY returned by the subroutine |
| | 2159 | HWDTOP. At present decay occurs before hadronization (DECAY=.TRUE.) |
| | 2160 | if the top mass is above 130 GeV (default=170 GeV). Any hypothetical |
| | 2161 | heavier quarks always decay before hadronization. Top- and bottom- |
| | 2162 | flavoured hadrons are split into collinear heavy quark and spectator |
| | 2163 | and the former decays independently. After decay, parton showers may |
| | 2164 | be generated from coloured decay products, in the usual way. See |
| | 2165 | Nucl. Phys. B330 (1990) 261 for details of the treatment of colour |
| | 2166 | coherence in these showers. |
| | 2167 | |
| | 2168 | The arrays FBTM, FTOP & FHVY which were used in versions before 5.9 |
| | 2169 | to store the bottom, top & heavier quarks' partonic decay fractions |
| | 2170 | are gone. Such decays are specified in the decay tables like other |
| | 2171 | particles' decay modes: this permits different decays to be given to |
| | 2172 | individual heavy hadrons. Changes to the decay table entries can be |
| | 2173 | made on an event by event basis if desired. Partonic decays of charm |
| | 2174 | hadrons and quarkonium states are also now supported. The products' |
| | 2175 | order in a partonic decay mode is significant. For example, if the |
| | 2176 | decay is Q --> W+q --> (f+fbar')+q occurring inside a Q-sbar hadron, |
| | 2177 | the required ordering is: |
| | 2178 | |
| | 2179 | Q+sbar --->(f+fbar')+(q+sbar) |
| | 2180 | or (q+fbar')+(f+sbar) `colour rearranged' |
| | 2181 | |
| | 2182 | In both cases the (V-A)^2 ME^2 is proportional to: p_0.p_2 * p_1*p_3 |
| | 2183 | |
| | 2184 | The structure of the program has been altered so that secondary hard |
| | 2185 | subrocess and subsequent fragmentation associated with each partonic |
| | 2186 | heavy hadron decay appear separately. Thus pre-hadronization t quark |
| | 2187 | decays are treated individually as are any subsequent bottom hadron |
| | 2188 | partonic decays. |
| | 2189 | |
| | 2190 | Additionally decays of heavy hadrons to exclusive non-partonic final |
| | 2191 | states are supported. No check against double counting from partonic |
| | 2192 | modes is included. However this isn't expected to be a major problem |
| | 2193 | for the semi-leptonic and 2-body hadronic modes supplied. |
| | 2194 | ------------------------------------------------------------------------ |
| | 2195 | |
| | 2196 | ****** 13. SPACE-TIME STRUCTURE OF EVENTS ****** |
| | 2197 | |
| | 2198 | The space-time structure of events is now available for all types of |
| | 2199 | subprocess. The production vertex of each: parton, cluster, unstable |
| | 2200 | resonance and final state particle is supplied in the VHEP(4,NMXHEP) |
| | 2201 | array of /HEPEVT/; set PRVTX=.TRUE. to include this information when |
| | 2202 | printing the event record (120 column format). The units are: x,y,z |
| | 2203 | in mm and t mm/c. In the case of partons and clusters the production |
| | 2204 | points are always given in a loacl coordinate system centered on the |
| | 2205 | their hard sub-process. This helps seperate the fermi scale partonic |
| | 2206 | showers from millimeter scale distances possible in particle decays, |
| | 2207 | for example the partonic decays of heavy (c,b) hadrons. The vertices |
| | 2208 | of hadrons produced in cluster decays are always corrected back into |
| | 2209 | the laboratory coordinate system. |
| | 2210 | |
| | 2211 | It is possible to vary the principal interaction point, assigned to |
| | 2212 | the CMF (ISTHEP=103) track, by setting PIPSMR=.TRUE. The smearing is |
| | 2213 | generated by the routine HWRPIP according to a triple Gaussian, see |
| | 2214 | the code for details. Also, it is possible to veto particle decays |
| | 2215 | that would occur outside a specified volume by setting MAXDKL=.TRUE. |
| | 2216 | Each putative decay is tested in HWDXLM and if it would have decayed |
| | 2217 | outside the chosen volume it is frozen and labelled as final state. |
| | 2218 | Using IOPDKL = 1,2 selects a cylindrical or spherical allowed region |
| | 2219 | (about the origin) see the code for details. |
| | 2220 | |
| | 2221 | Lepton and hadron lifetimes are supplied in the array RLTIM(NMXRES). |
| | 2222 | The lifetimes of heavy quarks (TQRK, VQRK, AQRK, HQRK AND HPQK), and |
| | 2223 | weak bosons (W+, W-, Z0/GAMA*, HIGGS and Z0P) are derived from their |
| | 2224 | calculated or specified widths as calculated in HWUDKS, whilst light |
| | 2225 | quarks and gluons are given an effective minimum width, sqrt(VMIN2), |
| | 2226 | that acts as a lifetime cut-off - see below. Recall that the proper |
| | 2227 | lifetime = HBAR/Gamma. All particles whose lifetimes are larger than |
| | 2228 | PLTCUT are set stable. |
| | 2229 | |
| | 2230 | The proper (= rest frame) time at which an unstable lepton or hadron |
| | 2231 | decays is generated according to the exponential decay law with mean |
| | 2232 | lifetime <tau>=RLTIM. The laboratory frame decay time and distance |
| | 2233 | travelled are obtained by applying a boost: |
| | 2234 | |
| | 2235 | Rest Prob (proper time < t) = 1 * exp(-t/<tau>) |
| | 2236 | frame <tau> |
| | 2237 | |
| | 2238 | Lab. time = gamma * proper time beta = v/c |
| | 2239 | frame dist = beta * gamma * proper time gamma = 1/sqrt(1-beta^2) |
| | 2240 | |
| | 2241 | The production vertices of the daughter particles are calculated by |
| | 2242 | adding the distance travelled by the mother particle as given above |
| | 2243 | to its production vertex. A similar prescription is used for parton |
| | 2244 | showers: proper lifetimes are taken from an exponential distribution |
| | 2245 | with a virtuality dependent mean lifetime 1/HBAR*sqrt(q^2/(q^2-m^2)) |
| | 2246 | inspired by the uncertainty relationship: mean lifetimes are limited |
| | 2247 | by a cut-off on the minimum virtuality VMIN2. The mean lifetimes of |
| | 2248 | heavy quarks and weak bosons, which can have appreciable widths, are |
| | 2249 | given by: |
| | 2250 | |
| | 2251 | hbar.sqrt(q^2) |
| | 2252 | <tau>(q^2) = ----------------------------- |
| | 2253 | \/(q^2-M^2)^2 + (Gamma.q^2/M)^2 |
| | 2254 | |
| | 2255 | As this formula has the appropriate limits for vanishing virtuality, |
| | 2256 | q^2=m^2, or width, gamma=0, it is actually also used in the hadronic |
| | 2257 | and partonic showers: see HWUDKL. |
| | 2258 | |
| | 2259 | In the case of cluster the initial production vertex is taken as the |
| | 2260 | midpoint of a line perpendicular to the cluster's direction and with |
| | 2261 | pair. If such a cluster undergoes a forced splitting to two clusters |
| | 2262 | the string picture is adopted. The vertex of the light quark pair is |
| | 2263 | positioned so that the masses of the two daughter clusters would be |
| | 2264 | the same as that for two equivalent string fragments. The production |
| | 2265 | vertices of the daughter clusters are given by the first crossing of |
| | 2266 | their constituent q-qbar pairs. This part of the space-time picture |
| | 2267 | is admittedly ad hoc however no physics depends upon it. |
| | 2268 | |
| | 2269 | When MIXING=.TRUE. particle - antiparticle mixing for B^0_d,s mesons |
| | 2270 | is implimented. The probability that a meson is mixed when it decays |
| | 2271 | is given in terms of its lab-frame decay time by: |
| | 2272 | |
| | 2273 | 1 sin(X*m*t/c<tau>E) X=Delta-M Y=Delta-Gamma |
| | 2274 | Prob(mix) = - + ---------------------- ------- ----------- |
| | 2275 | 2 2 *cosh(Y*m*t/c<tau>E) Gamma 2 * Gamma |
| | 2276 | |
| | 2277 | The ratios X and Y are stored in XMIX(I) & YMIX(I), I=1,2 for q=s,d. |
| | 2278 | Whenever a neutral B meson occurs in an event a copy of the original |
| | 2279 | track is always added to the event record, with ISTHEP=200, it gives |
| | 2280 | the particle's flavour at the production (cluster decay) time. This |
| | 2281 | is in addition to the usual decaying particle, ISTHEP=19*, track. |
| | 2282 | ------------------------------------------------------------------------ |
| | 2283 | |
| | 2284 | ****** 14. COLOUR REARRANGEMENT MODEL ****** |
| | 2285 | |
| | 2286 | HERWIG now contains a colour rearrangement model based on the space- |
| | 2287 | time structure of an event occuring at the end of the parton shower. |
| | 2288 | This is illustrated in the simple example shown below where a colour |
| | 2289 | neutral source results in a q-g-g-qbar shower. In the conventional |
| | 2290 | hadronization model after a nonperturbative splitting of final state |
| | 2291 | gluons - Wolfram ansatze - colour singlet clusters are formed from |
| | 2292 | neighbouring q-qbar pairs: (ij)(pq)(kl). However when CLRECO=.TRUE. |
| | 2293 | the program first creates colour singlet clusters as normal but then |
| | 2294 | checks all (non-neighbouring) pairs of clusters to test if a colour |
| | 2295 | rearrangement lowers the sum of the clusters' spatial sizes added in |
| | 2296 | quadrature. A cluster's size is defined to be the Lorentz invariant, |
| | 2297 | space-time distance between the constituent quark's and anitquark's |
| | 2298 | production points. If an allowed alternative is found, that is: |
| | 2299 | |
| | 2300 | (ij)(kl) --> (il)(jk) s.t. (|d_ij|^2+|d_kl|^2) > (|d_il|^2+|d_kl|^2) |
| | 2301 | |
| | 2302 | then it is accepted with a probability given by PRECO (default 1/9). |
| | 2303 | |
| | 2304 | |
| | 2305 | ____ i Normal: (ij) (pq) (kl) |
| | 2306 | / |
| | 2307 | /____/ j If: |
| | 2308 | ------ |
| | 2309 | / \ p |d_ij|^2+|d_kl|^2 > |d_il|^2+|d_kl|^2 |
| | 2310 | ------| |
| | 2311 | \______/ q colour rearr.: (il) (pq) (jk) |
| | 2312 | ----- |
| | 2313 | \ \ k Not allowed: (iq) (jp) (kl) |
| | 2314 | \ ^ |
| | 2315 | ---- l | colour octet |
| | 2316 | |
| | 2317 | Note that not all colour rearrangements are allowed, for instance in |
| | 2318 | the example (ij)(pq) --> (ip)(jq) the cluster (jq) is a colour octet |
| | 2319 | - it contains both products from a non-perturbative gluon splitting. |
| | 2320 | |
| | 2321 | Multiple colour rearrangements are considered by the program, as are |
| | 2322 | those between clusters in jets arising from a single, colour neutral |
| | 2323 | source - for example Z0 decay (as shown above) - or due to more than |
| | 2324 | one source - for example e+e- --> W+W- --> 4 jets. In the later case |
| | 2325 | a new parameter, EXAG, is available to artificially scale the W - or |
| | 2326 | other weak boson - lifetimes so that any dependence of rearrangement |
| | 2327 | effects on source separation can be investigated. The CLRECO option |
| | 2328 | can be used for all the processes available in HERWIG. |
| | 2329 | |
| | 2330 | ** NOTE ** Before using the program with CLRECO=.TRUE. for detailed |
| | 2331 | physics analyses the default parameters should be retuned to `lower |
| | 2332 | energy' data with this option switched on. |
| | 2333 | ------------------------------------------------------------------------ |
| | 2334 | |
| | 2335 | ****** 15. QCD HARD SUBPROCESSES ****** |
| | 2336 | |
| | 2337 | At present only 2->2 subprocesses are implemented. They are class- |
| | 2338 | ified as shown below. |
| | 2339 | |
| | 2340 | +-----+------------------------------+---------+ |
| | 2341 | |IHPRO| Process 1 + 2 -> 3 + 4 |Col/F.Con| |
| | 2342 | +-----+------------------------------+---------+ |
| | 2343 | | 1 | q + q -> q + q | 3 4 2 1 | |
| | 2344 | | 2 | q + q -> q + q | 4 3 1 2 | |
| | 2345 | | 3 | q + q' -> q + q' | 3 4 2 1 | |
| | 2346 | | 4 | q + qbar -> q'+ qbar' | 2 4 1 3 | |
| | 2347 | | 5 | q + qbar -> q + qbar | 3 1 4 2 | |
| | 2348 | | 6 | q + qbar -> q + qbar | 2 4 1 3 | |
| | 2349 | | 7 | q + qbar -> g + g | 2 4 1 3 | |
| | 2350 | | 8 | q + qbar -> g + g | 2 3 4 1 | |
| | 2351 | | 9 | q + qbar' -> q + qbar' | 3 1 4 2 | |
| | 2352 | | 10 | q + g -> q + g | 3 1 4 2 | |
| | 2353 | | 11 | q + g -> q + g | 3 4 2 1 | |
| | 2354 | | 12 | qbar + q -> qbar' +q' | 3 1 4 2 | |
| | 2355 | | 13 | qbar + q -> qbar + q | 2 4 1 3 | |
| | 2356 | | 14 | qbar + q -> qbar + q | 3 1 4 2 | |
| | 2357 | | 15 | qbar + q -> g + g | 3 1 4 2 | |
| | 2358 | | 16 | qbar + q -> g + g | 4 1 2 3 | |
| | 2359 | | 17 | qbar + q' -> qbar + q' | 2 4 1 3 | |
| | 2360 | | 18 | qbar + qbar -> qbar + qbar | 4 3 1 2 | |
| | 2361 | | 19 | qbar + qbar -> qbar + qbar | 3 4 2 1 | |
| | 2362 | | 20 | qbar + qbar' -> qbar + qbar' | 4 3 1 2 | |
| | 2363 | | 21 | qbar + g -> qbar + g | 2 4 1 3 | |
| | 2364 | | 22 | qbar + g -> qbar + g | 4 3 1 2 | |
| | 2365 | | 23 | g + q -> g + q | 2 4 1 3 | |
| | 2366 | | 24 | g + q -> g + q | 3 4 2 1 | |
| | 2367 | | 25 | g + qbar -> g + qbar | 3 1 4 2 | |
| | 2368 | | 26 | g + qbar -> g + qbar | 4 3 1 2 | |
| | 2369 | | 27 | g + g -> q + qbar | 2 4 1 3 | |
| | 2370 | | 28 | g + g -> q + qbar | 4 1 2 3 | |
| | 2371 | | 29 | g + g -> g + g | 4 1 2 3 | |
| | 2372 | | 30 | g + g -> g + g | 4 3 1 2 | |
| | 2373 | | 31 | g + g -> g + g | 2 4 1 3 | |
| | 2374 | +-----+------------------------------+---------+ |
| | 2375 | |
| | 2376 | `Col/F.Con' refers to the colour/flavour connections between the |
| | 2377 | partons:`I J K L' means that the colour of parton 1 comes from parton |
| | 2378 | I, that of 2 from J, etc. For antiquarks, which have no colour (only |
| | 2379 | anticolour), the label shows instead to which parton the flavour is |
| | 2380 | connected. For this colour/flavour labelling all partons are defined |
| | 2381 | as outgoing. Thus, for example, process 10 has colour connections |
| | 2382 | 3 1 4 2, corresponding to the colour flow diagram: |
| | 2383 | |
| | 2384 | 1 -->--+ +-->-- 3 |
| | 2385 | | | |
| | 2386 | | | |
| | 2387 | --<--+ +--<-- |
| | 2388 | 2 -->------->-- 4 |
| | 2389 | |
| | 2390 | When different colour flows are possible, they are listed as separate |
| | 2391 | subprocesses. This separation is not exact but is normally a good |
| | 2392 | approximation. The sum of the colour flows is the exact lowest-order |
| | 2393 | cross section. |
| | 2394 | ------------------------------------------------------------------------ |
| | 2395 | |
| | 2396 | ****** 16. QCD DIRECT PHOTON SUBPROCESSES ****** |
| | 2397 | |
| | 2398 | +-----+------------------------------+---------+ |
| | 2399 | |IHPRO| Process 1 + 2 -> 3 + 4 |Col/F.Con| |
| | 2400 | +-----+------------------------------+---------+ |
| | 2401 | | 41 | q + qbar -> g + photon | 2 3 1 4 | |
| | 2402 | | 42 | q + gluon -> q + photon | 3 1 2 4 | |
| | 2403 | | 43 | qbar + q -> g + photon | 3 1 2 4 | |
| | 2404 | | 44 | qbar + gluon -> qbar + photon| 2 3 1 4 | |
| | 2405 | | 45 | gluon + q -> q + photon| 2 3 1 4 | |
| | 2406 | | 46 | gluon + qbar -> qbar + photon| 3 1 2 4 | |
| | 2407 | | 47 | gluon + gluon-> gluon+ photon| 2 3 1 4 | |
| | 2408 | +-----+------------------------------+---------+ |
| | 2409 | | 51 | photon+ q -> gluon+ q | 1 4 2 3 | |
| | 2410 | | 52 | photon+ qbar -> gluon+ qbar | 1 3 4 2 | |
| | 2411 | | 53 | photon+ gluon-> q + qbar | 1 4 2 3 | |
| | 2412 | +-----+------------------------------+---------+ |
| | 2413 | | 61 | q + qbar -> photon+photon| 2 1 3 4 | |
| | 2414 | | 62 | qbar + q -> photon+photon| 2 1 3 4 | |
| | 2415 | | 63 | gluon + gluon-> photon+photon| 2 1 3 4 | |
| | 2416 | +-----+------------------------------+---------+ |
| | 2417 | | 71 | photon+ q -> M(S=0) +q' | 1 4 3 2 | |
| | 2418 | | 72 | photon+ q -> M(S=1)L+q' | 1 4 3 2 | |
| | 2419 | | 73 | photon+ q -> M(S=1)T+q' | 1 4 3 2 | |
| | 2420 | | 74 | photon+ qbar -> M(S=0) +qbar'| 1 4 3 2 | |
| | 2421 | | 75 | photon+ qbar -> M(S=1)L+qbar'| 1 4 3 2 | |
| | 2422 | | 76 | photon+ qbar -> M(S=1)T+qbar'| 1 4 3 2 | |
| | 2423 | +-----+------------------------------+---------+ |
| | 2424 | |
| | 2425 | N.B. The photon is connected to itself. |
| | 2426 | ------------------------------------------------------------------------ |
| | 2427 | |
| | 2428 | ****** 17. QCD HIGGS PLUS JET SUBPROCESSES ****** |
| | 2429 | |
| | 2430 | +-----+------------------------------+---------+ |
| | 2431 | |IHPRO| Process 1 + 2 -> 3 + 4 |Col/F.Con| |
| | 2432 | +-----+------------------------------+---------+ |
| | 2433 | | 81 | q + qbar -> g + H | 2 3 1 4 | |
| | 2434 | | 82 | q + g -> q + H | 3 1 2 4 | |
| | 2435 | | 83 | qbar + q -> g + H | 3 1 2 4 | |
| | 2436 | | 84 | qbar + g -> qbar + H | 2 3 1 4 | |
| | 2437 | | 85 | g + q -> q + H | 2 3 1 4 | |
| | 2438 | | 86 | g + qbar -> qbar + H | 3 1 2 4 | |
| | 2439 | | 87 | g + g -> g + H | 2 3 1 4 | |
| | 2440 | +-----+------------------------------+---------+ |
| | 2441 | |
| | 2442 | N.B. The Higgs is connected to itself. |
| | 2443 | ------------------------------------------------------------------------ |
| | 2444 | |
| | 2445 | ****** 18. ELECTROWEAK SUBPROCESSES ****** |
| | 2446 | |
| | 2447 | HERWIG generates Higgs bosons through gluon-gluon/quark-antiquark |
| | 2448 | fusion, and W fusion in hadron-hadron collisions (IPROC=1600+ID and |
| | 2449 | 1900+ID), in lepton-lepton collisions through the Bjorken process |
| | 2450 | (that is, Z(*)->Z(*)H with one or both Zs off-shell) and W fusion |
| | 2451 | (IPROC=300+ID and 400+ID), and in lepton-hadron collisions through W |
| | 2452 | fusion (IPROC=9500+ID). Each process is generated according to the |
| | 2453 | exact leading order matrix element in the s-channel approximation. |
| | 2454 | This results in unitarity violation for Mh >> Mw, s >~ a few Mh^2, |
| | 2455 | (where s=qh^2), so to regularize this, the Mh*GAMH in the propagator |
| | 2456 | can be replaced by SQRT(s)*GAMH(s). The variable IOPHIG controls this |
| | 2457 | procedure: |
| | 2458 | |
| | 2459 | +------+------------------------------+-----------+ |
| | 2460 | |IOPHIG| Choose s according to | Reweight? | |
| | 2461 | +------+------------------------------+-----------+ |
| | 2462 | | 0 | s^2 / ((s-Mh^2)^2 + Mh*GAMH) | YES | |
| | 2463 | | 1 | 1 / ((s-Mh^2)^2 + Mh*GAMH) | YES | |
| | 2464 | | 2 | s^2 / ((s-Mh^2)^2 + Mh*GAMH) | NO | |
| | 2465 | | 3 | 1 / ((s-Mh^2)^2 + Mh*GAMH) | NO | |
| | 2466 | +------+------------------------------+-----------+ |
| | 2467 | |
| | 2468 | Where reweighting means weighting the distribution back to |
| | 2469 | |
| | 2470 | SQRT(s) * GAMH(s) |
| | 2471 | ---------------------------- |
| | 2472 | (s-Mh^2)^2 + SQRT(s)*GAMH(s) |
| | 2473 | |
| | 2474 | The default is IOPHIG=1. The difference between options 0 and 1 is |
| | 2475 | purely in the weight distribution produced. Options 2 and 3 are |
| | 2476 | intended primarily for users who wish to supply their own unitarity |
| | 2477 | conserving reweighting function at the point indicated in routine |
| | 2478 | HWHIGM. In all cases, the distribution is restricted to the range |
| | 2479 | [Mh-GAMMAX*GAMH , Mh+GAMMAX*GAMH]. GAMMAX defaults to 10, but in the |
| | 2480 | (probably unphysical) region Mh >~ 1TeV should be reduced to protect |
| | 2481 | against poor weight distributions. These considerations do not affect |
| | 2482 | the distribution noticably for Mh <~ 500 GeV, and GAMMAX can safely |
| | 2483 | be increased if necessary. |
| | 2484 | |
| | 2485 | For each process, ID controls the Higgs decay: ID=1-6 for quarks, 7-9 |
| | 2486 | for leptons, 10/11 for WW/ZZ pairs, and 12 for photons. In addition |
| | 2487 | ID=0 gives quarks of all flavours, and ID=99 gives all decays. For |
| | 2488 | each process, the average event weight is the cross section in nb |
| | 2489 | times the branching fraction to the requested decay. The branching |
| | 2490 | ratios to quarks use the next-to-leading logarithm corrections, those |
| | 2491 | to WW/ZZ pairs allow for one or both bosons off-shell. The amplitudes |
| | 2492 | for all Higgs vertices are multiplied by the factor ENHANC(ID) where |
| | 2493 | ID is the same as in IPROC=300+ID except the gammagammaHiggs `vertex' |
| | 2494 | which is calculated from ENHANC(6) and ENHANC(10) for the top and W |
| | 2495 | loops. This allows the simulation of any chargeless scalar Higgs. |
| | 2496 | Note however that pseudoscalar and charged Higgses, and processes |
| | 2497 | involving more than one Higgs (eg the decay H-->hZ) are not included. |
| | 2498 | |
| | 2499 | Gauge bosons are generated through the processes of W + 1 parton |
| | 2500 | production in hadron-hadron collisions, and WW pair production in |
| | 2501 | lepton-lepton collisions, as well as in the Higgs processes mentioned |
| | 2502 | above. In all cases their decay is controlled by the variable |
| | 2503 | MODBOS(i). This controls the decay of the ith gauge boson per event: |
| | 2504 | |
| | 2505 | +---------+-----------------+-----------------+ |
| | 2506 | |MODBOS(i)| W Decay | Z Decay | |
| | 2507 | +---------+-----------------+-----------------+ |
| | 2508 | | 0 | all | all | |
| | 2509 | | 1 | qqbar | qqbar | |
| | 2510 | | 2 | enu | e+e- | |
| | 2511 | | 3 | munu | mu+mu- | |
| | 2512 | | 4 | taunu | tau+tau- | |
| | 2513 | | 5 | enu & munu | ee & mumu | |
| | 2514 | | 6 | all | nunu | |
| | 2515 | | 7 | all | bbbar | |
| | 2516 | | >7 | all | all | |
| | 2517 | +---------+-----------------+-----------------+ |
| | 2518 | |
| | 2519 | All entries of MODBOS default to 0. Bosons which are produced in |
| | 2520 | pairs (ie. from WW pair production, or Higgs decay) are symmetrized |
| | 2521 | in MODBOS(i) and MODBOS(i+1). For processes which directly produce |
| | 2522 | gauge bosons, the event weight includes the branching fraction to the |
| | 2523 | requested decay, but this is only true for Higgs production if decay |
| | 2524 | to WW/ZZ is forced (ID=10/11) and not if ID=99. The spin-correlations |
| | 2525 | in the decays are handled in one of two ways: |
| | 2526 | (a) the diagonal members of the spin density matrix are stored in |
| | 2527 | RHOHEP(i,IHEP), where i=1,2,3 for helicity=i-2 in the centre-of- |
| | 2528 | mass frame of their production, for processes where this matrix |
| | 2529 | is diagonal (ie. there is no interference between spin states). |
| | 2530 | (b) the correlations in the decay are handled directly by the |
| | 2531 | production routine where (a) is not possible. |
| | 2532 | In the case of gamma gamma --> W W the decay correlations are not |
| | 2533 | correctly included: they currently decay isotropically. |
| | 2534 | |
| | 2535 | The electroweak vector boson--fermion coupling constants are stored |
| | 2536 | in the arrays QFCH(I), VFCH(I,J) and AFCH(I,J) for the charge, vector |
| | 2537 | and axial vector couplings to the neutral current respectively. These |
| | 2538 | are given in the convention |
| | 2539 | V_f=(T_3/2-Qsin^2_W)/(cos_W sin_W); A_f=T_3/(2 cos_W sin_W). |
| | 2540 | In each case, |
| | 2541 | I= 1- 6: d,u,s,c,b,t (quarks) |
| | 2542 | =11-16: e,nu_e,mu,nu_mu,tau,nu_tau (leptons) (`I=IDHW-110') |
| | 2543 | J=1 for minimal SM: |
| | 2544 | =2 for Z' couplings (only included if ZPRIME=.TRUE.) |
| | 2545 | Note that no universality is assumed -- couplings can be arbitrarily |
| | 2546 | set for each fermion species separately. |
| | 2547 | The quark mixing matrix is stored in VCKM(K,L), K=1,2,3 for u,c,t, |
| | 2548 | L=1,2,3 for d,s,b. |
| | 2549 | |
| | 2550 | A running electromagnetic coupling constant is provided, HWUAEM(Q2). |
| | 2551 | ALPHEM =1/137 provides the normalisation at the Thomson (Q2=0) limit |
| | 2552 | and is used for all processes involving real photons. |
| | 2553 | The electroweak coupling is calculated as, |
| | 2554 | g^2 = 4 PIFAC ALPHEM(Q2) / SWEIN, |
| | 2555 | where Q2 is appropriate for the given process. |
| | 2556 | Photon emission in parton showers, and in the `dead-zone' in e+e- |
| | 2557 | is enhanced by a factor of ALPFAC (default=1.). |
| | 2558 | ------------------------------------------------------------------------ |
| | 2559 | |
| | 2560 | ****** 19. INCLUDING NEW SUBPROCESSES ****** |
| | 2561 | |
| | 2562 | It should not be difficult for users to include further subprocesses |
| | 2563 | in this version of the program if required. The parton and hard sub- |
| | 2564 | process 4-momenta, masses and identity codes need to be entered in |
| | 2565 | COMMON/HEPEVT/ with the appropriate status codes ISTHEP(I)=110-114 to |
| | 2566 | tell the program which is which (see table in sect. 10). The colour/ |
| | 2567 | flavour structure should be specified by the second mother and daugh- |
| | 2568 | ter pointers as explained in section 9 (see also the sample output |
| | 2569 | and guide, sections. 20 and 21). |
| | 2570 | |
| | 2571 | Apart from the status codes ISTHEP, the HERWIG identity codes IDHW(I) |
| | 2572 | in COMMON/HWEVNT/ also need to be set correctly. The IDHW codes can |
| | 2573 | be listed in a run with IPRINT=2: the most important are the quarks |
| | 2574 | 1-6 (as IDHEP), antiquarks 7-12, gluon 13, overall c.m. 14, hard c.m. |
| | 2575 | 15, soft c.m. 16, photon 59, leptons 121-126, antileptons 127-132. |
| | 2576 | |
| | 2577 | The utility subroutine HWUIDT(IOPT,IPDG,IHWG,NAME) is provided to |
| | 2578 | translate between Particle Data Group code IPDG, HERWIG code IHWG, |
| | 2579 | and HERWIG character*8 NAME, with IOPT=1,2,3 depending on which of |
| | 2580 | IPDG, IHWG and NAME is the input argument. |
| | 2581 | |
| | 2582 | Consider for example the process of virtual photon-gluon fusion to |
| | 2583 | make b+bbar in e p collisions. |
| | 2584 | |
| | 2585 | **** N.B. This process is now included as IPROC = 9102 **** |
| | 2586 | |
| | 2587 | We assume the user provides a subroutine to generate the momenta PHEP |
| | 2588 | for the hard subprocess e+g -> e+b+bbar. The colour structure is |
| | 2589 | |
| | 2590 | (e)4 ........... 7(e) |
| | 2591 | : |
| | 2592 | : |
| | 2593 | +-->-- 8(b) |
| | 2594 | | |
| | 2595 | -->--+ |
| | 2596 | (g)5 --<-----<-- 9(bbar) |
| | 2597 | |
| | 2598 | Thus the momenta generated, together with those of the initial beams |
| | 2599 | and the overall centre of mass, could be entered in the following |
| | 2600 | sequence: |
| | 2601 | |
| | 2602 | +----+--------+------+-----+------+------+----+ |
| | 2603 | |IHEP| Entry |ISTHEP|IDHEP|JMOHEP|JDAHEP|IDHW| |
| | 2604 | +----+--------+------+-----+------+------+----+ |
| | 2605 | | 1 | e beam | 101 | 11| 0 0| 0 0| 121| |
| | 2606 | | 2 | p beam | 102 | 2212| 0 0| 0 0| 73| |
| | 2607 | | 3 | ep c.m.| 103 | 0| 0 0| 0 0| 14| |
| | 2608 | +----+--------+------+-----+------+------+----+ |
| | 2609 | | 4 | e in | 111 | 11| 6 7| 0 7| 121| |
| | 2610 | | 5 | gluon | 112 | 21| 6 9| 0 8| 13| |
| | 2611 | | 6 | hard cm| 110 | 0| 4 5| 7 9| 15| |
| | 2612 | | 7 | e out | 113 | 11| 6 4| 0 4| 121| |
| | 2613 | | 8 | b | 114 | 5| 6 5| 0 9| 5| |
| | 2614 | | 9 | bbar | 114 | -5| 6 8| 0 5| 11| |
| | 2615 | +----+--------+------+-----+------+------+----+ |
| | 2616 | |
| | 2617 | Note that if there are more than two outgoing partons, the first has |
| | 2618 | status 113 and all the others 114. Each parton has JMOHEP(1,I)=6 to |
| | 2619 | indicate the location of the hard c.m. for this subprocess, while |
| | 2620 | JMOHEP(2,I) gives the location of the colour mother (treating the in- |
| | 2621 | coming gluon as outgoing) or the connected electron. JDAHEP(1,I) will |
| | 2622 | be set by the jet generator HWBGEN, while JDAHEP(2,I) points to the |
| | 2623 | anticolour mother (or connected electron). Finally the HERWIG identi- |
| | 2624 | fiers IDHW(I) could be set to the indicated values by means of the |
| | 2625 | translation subroutine HWUIDT as follows: |
| | 2626 | |
| | 2627 | CHARACTER*8 NAME |
| | 2628 | ..... |
| | 2629 | NHEP=9 |
| | 2630 | IDHEP(1)=11 |
| | 2631 | IDHEP(2)=2212 |
| | 2632 | ..... |
| | 2633 | IDHEP(9)=-5 |
| | 2634 | DO 10 I=1,NHEP |
| | 2635 | 10 CALL HWUIDT(1,IDHEP(I),IDHW(I),NAME) |
| | 2636 | IDHW(6)=15 |
| | 2637 | |
| | 2638 | The last statement is needed because IDPDG(I)=0 returns IDHW(I)=14. |
| | 2639 | If subroutine HWBGEN is now called, it will find the coloured partons |
| | 2640 | and generate QCD jets from them. Subsequent calls to HWCFOR etc can |
| | 2641 | then be used to form clusters and hadronize them. |
| | 2642 | |
| | 2643 | If the hard subprocess routine is called from HWEPRO, like those |
| | 2644 | already provided, it should have two options controlled by the logic- |
| | 2645 | al variable GENEV in COMMON/HWHARD/. For GENEV=.FALSE., an event |
| | 2646 | weight (normally the cross section in nanobarns) is generated and |
| | 2647 | stored as EVWGT in COMMON/HWEVNT/. If this weight is accepted by |
| | 2648 | HWEPRO, the subroutine is called a second time with GENEV=.TRUE. and |
| | 2649 | the corresponding event data should then be generated and stored as |
| | 2650 | explained above. |
| | 2651 | ------------------------------------------------------------------------ |
| | 2652 | |
| | 2653 | ****** 20. ERROR CONDITIONS ****** |
| | 2654 | |
| | 2655 | Certain combinations of input parameters may lead to problems in exe- |
| | 2656 | cution. HERWIG tries to detect these and print a warning. Errors |
| | 2657 | during execution are dealt with by HWWARN which prints the calling |
| | 2658 | subprogram and a code and takes appropriate action. In general, the |
| | 2659 | larger the code the more serious the problem. Refer to the source |
| | 2660 | code to find out why HWWARN was called. Events can be rerun by |
| | 2661 | setting the random number seeds NRN to the values given in the error |
| | 2662 | message or event dump, and MAXWGT to the maximum weight encountered |
| | 2663 | in the run. Contents of /HEPEVT/ can by printed by calling HWUEPR, |
| | 2664 | those of /HWPART/ (last parton shower) by HWUBPR. |
| | 2665 | |
| | 2666 | If WGTMAX is increased during event generation, so that this message |
| | 2667 | is printed: |
| | 2668 | HWWARN CALLED FROM SUBPROGRAM HWEPRO: CODE = 1 |
| | 2669 | EVENT 21: SEEDS = 836291635 & 1823648329 WEIGHT = 0.3893E-08 |
| | 2670 | EVENT SURVIVES. EXECUTION CONTINUES |
| | 2671 | NEW MAXIMUM WEIGHT = 0.428217360829367E-08 |
| | 2672 | then to regenerate any later events, WGTMAX must be set to the printed |
| | 2673 | value, as well as setting NRN to the appropriate seeds. |
| | 2674 | |
| | 2675 | Examples of error messages: |
| | 2676 | |
| | 2677 | HWWARN CALLED FROM SUBPROGRAM HWSBRN: CODE = 101 |
| | 2678 | EVENT 31: SEEDS = 422399901 & 771980111 WEIGHT = 0.3893E-08 |
| | 2679 | EVENT KILLED. EXECUTION CONTINUES |
| | 2680 | |
| | 2681 | Spacelike (initial-state) parton branching had no phase space. This |
| | 2682 | can happen due to cutoffs which are slightly different in the hard |
| | 2683 | subprocess and the parton shower. |
| | 2684 | Action taken: program throws away this event and starts a new one. |
| | 2685 | |
| | 2686 | HWWARN CALLED FROM SUBPROGRAM HWCHAD: CODE = 102 |
| | 2687 | EVENT 51: SEEDS = 1033784787 & 1428957533 WEIGHT = 0.3893E-08 |
| | 2688 | EVENT KILLED. EXECUTION CONTINUES |
| | 2689 | |
| | 2690 | A cluster has been formed with too low a mass to represent any hadron |
| | 2691 | of the correct flavour, and there is no colour-connected cluster from |
| | 2692 | which the necessary additional mass could be transferred. |
| | 2693 | Action taken: program throws away this event and starts a new one. |
| | 2694 | |
| | 2695 | HWWARN CALLED FROM SUBPROGRAM HWUINE: CODE= 200 |
| | 2696 | EVENT SURVIVES. RUN ENDS GRACEFULLY |
| | 2697 | |
| | 2698 | CPU time limit liable to be reached before generating MAXEV events. |
| | 2699 | Action taken: skips to terminal calculations using existing events. |
| | 2700 | |
| | 2701 | HWWARN CALLED FROM SUBPROGRAM HWBSUD: CODE= 500 |
| | 2702 | RUN CANNOT CONTINUE |
| | 2703 | |
| | 2704 | The table of Sudakov form factors read on unit LRSUD does not extend |
| | 2705 | to the maximum momentum scale (QLIM) specified for this run. |
| | 2706 | Action taken: run aborted. The user must either reduce QLIM or set |
| | 2707 | LRSUD=0 to make a bigger table (set LWSUD nonzero to write it). |
| | 2708 | |
| | 2709 | HWWARN CALLED FROM SUBPROGRAM HWBSUD: CODE= 515 |
| | 2710 | RUN CANNOT CONTINUE |
| | 2711 | |
| | 2712 | The table of Sudakov form factors read on unit LRSUD is for a diff- |
| | 2713 | erent value of a relevant parameter (in this case the b quark mass). |
| | 2714 | Action taken: run aborted. The user must make a new table (set LWSUD |
| | 2715 | nonzero to write it). |
| | 2716 | ------------------------------------------------------------------------ |
| | 2717 | ****** 21. SAMPLE OUTPUT ****** |
| | 2718 | |
| | 2719 | Below we give a complete listing of output from version 5.9 of the |
| | 2720 | program, set up for t quark production in pbar-p collisions at a |
| | 2721 | c.m. energy of 1.8 TeV. To shorten the event record, the underlying |
| | 2722 | event has been turned off (IPROC = 11706) and production vertices are |
| | 2723 | not printed (PRVTX=.FALSE.). The main features of the output are |
| | 2724 | discussed in section 22. |
| | 2725 | |
| | 2726 | |
| | 2727 | HERWIG 5.9 22nd July 1996 |
| | 2728 | |
| | 2729 | Please reference: G. Marchesini, B.R. Webber, |
| | 2730 | G.Abbiendi, I.G.Knowles, M.H.Seymour & L.Stanco |
| | 2731 | Computer Physics Communications 67 (1992) 465 |
| | 2732 | |
| | 2733 | INPUT CONDITIONS FOR THIS RUN |
| | 2734 | |
| | 2735 | BEAM 1 (PBAR ) MOM. = 900.00 |
| | 2736 | BEAM 2 (P ) MOM. = 900.00 |
| | 2737 | PROCESS CODE (IPROC) = 11706 |
| | 2738 | NUMBER OF FLAVOURS = 6 |
| | 2739 | STRUCTURE FUNCTION SET = 5 |
| | 2740 | AZIM SPIN CORRELATIONS = T |
| | 2741 | AZIM SOFT CORRELATIONS = T |
| | 2742 | QCD LAMBDA (GEV) = 0.1800 |
| | 2743 | DOWN QUARK MASS = 0.3200 |
| | 2744 | UP QUARK MASS = 0.3200 |
| | 2745 | STRANGE QUARK MASS = 0.5000 |
| | 2746 | CHARMED QUARK MASS = 1.5500 |
| | 2747 | BOTTOM QUARK MASS = 4.9500 |
| | 2748 | TOP QUARK MASS = 170.0000 |
| | 2749 | GLUON EFFECTIVE MASS = 0.7500 |
| | 2750 | EXTRA SHOWER CUTOFF (Q)= 0.4800 |
| | 2751 | EXTRA SHOWER CUTOFF (G)= 0.1000 |
| | 2752 | PHOTON SHOWER CUTOFF = 0.4000 |
| | 2753 | CLUSTER MASS PARAMETER = 3.3500 |
| | 2754 | SPACELIKE EVOLN CUTOFF = 2.5000 |
| | 2755 | INTRINSIC P-TRAN (RMS) = 0.0000 |
| | 2756 | MIN P-TRAN FOR 2->2 = 10.0000 |
| | 2757 | MAX P-TRAN FOR 2->2 = 900.0002 |
| | 2758 | |
| | 2759 | NO EVENTS WILL BE WRITTEN TO DISK |
| | 2760 | |
| | 2761 | B_d: Delt-M/Gam =0.7000 Delt-Gam/2*Gam =0.0000 |
| | 2762 | B_s: Delt-M/Gam = 10.00 Delt-Gam/2*Gam =0.2000 |
| | 2763 | |
| | 2764 | PDFLIB NOT USED FOR BEAM 1 |
| | 2765 | PDFLIB NOT USED FOR BEAM 2 |
| | 2766 | |
| | 2767 | |
| | 2768 | Checking consistency of particle properties |
| | 2769 | |
| | 2770 | |
| | 2771 | Checking consistency of decay tables |
| | 2772 | |
| | 2773 | Line, 565 decay: LMBDA_C+ --> XI*0 K*+ |
| | 2774 | is kinematically not allowed, Min-Mout= -0.139 |
| | 2775 | LMBDA_C+: BR sum = 0.97800 |
| | 2776 | Rescaling to 1 |
| | 2777 | |
| | 2778 | Line, 990 decay: LMBDA_C- --> XI*BAR K*- |
| | 2779 | is kinematically not allowed, Min-Mout= -0.139 |
| | 2780 | LMBDA_C-: BR sum = 0.97800 |
| | 2781 | Rescaling to 1 |
| | 2782 | |
| | 2783 | |
| | 2784 | PARTICLE TYPE 21=PI0 SET STABLE |
| | 2785 | |
| | 2786 | INITIAL SEARCH FOR MAX WEIGHT |
| | 2787 | |
| | 2788 | PROCESS CODE IPROC = 11706 |
| | 2789 | RANDOM NO. SEED 1 = 1246579 |
| | 2790 | SEED 2 = 8447766 |
| | 2791 | NUMBER OF SHOTS = 2000 |
| | 2792 | NEW MAXIMUM WEIGHT = 1.1503371195500599E-03 |
| | 2793 | NEW MAXIMUM WEIGHT = 3.2720875047931022E-03 |
| | 2794 | NEW MAXIMUM WEIGHT = 3.4397725453424351E-02 |
| | 2795 | NEW MAXIMUM WEIGHT = 6.0381232770162795E-02 |
| | 2796 | NEW MAXIMUM WEIGHT = 6.6570674949068473E-02 |
| | 2797 | |
| | 2798 | INITIAL SEARCH FINISHED |
| | 2799 | |
| | 2800 | OUTPUT ON ELEMENTARY PROCESS |
| | 2801 | |
| | 2802 | NUMBER OF EVENTS = 0 |
| | 2803 | NUMBER OF WEIGHTS = 2000 |
| | 2804 | MEAN VALUE OF WGT = 4.5373E-03 |
| | 2805 | RMS SPREAD IN WGT = 9.3312E-03 |
| | 2806 | ACTUAL MAX WEIGHT = 6.0519E-02 |
| | 2807 | ASSUMED MAX WEIGHT = 6.6571E-02 |
| | 2808 | |
| | 2809 | PROCESS CODE IPROC = 11706 |
| | 2810 | CROSS SECTION (PB) = 4.537 |
| | 2811 | ERROR IN C-S (PB) = 0.2087 |
| | 2812 | EFFICIENCY PERCENT = 6.816 |
| | 2813 | |
| | 2814 | |
| | 2815 | |
| | 2816 | EVENT 39: 900.00 GEV/C PBAR ON 900.00 GEV/C P PROCESS: 11706 |
| | 2817 | |
| | 2818 | SEEDS: 875163092 & 655954870 STATUS: 100 ERROR: 0 WEIGHT: 0.4537E-02 |
| | 2819 | |
| | 2820 | ---INITIAL STATE--- |
| | 2821 | |
| | 2822 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 2823 | 1 PBAR -2212 101 0 0 0 0 0.00 0.00 900.00 900.00 0.94 |
| | 2824 | 2 P 2212 102 0 0 0 0 0.00 0.00 -900.00 900.00 0.94 |
| | 2825 | 3 CMF 0 103 1 2 0 0 0.00 0.00 0.00 1800.00 1800.00 |
| | 2826 | |
| | 2827 | ---HARD SUBPROCESS--- |
| | 2828 | |
| | 2829 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 2830 | 4 UBAR -2 121 6 7 9 5 0.00 0.00 312.09 312.09 0.32 |
| | 2831 | 5 UQRK 2 122 6 4 17 8 0.00 0.00 -169.95 169.95 0.32 |
| | 2832 | 6 HARD 0 120 4 5 7 8 -16.42 -3.93 142.14 482.34 460.61 |
| | 2833 | 7 TBAR -6 123 6 8 22 4 116.29 -61.69 157.43 266.49 170.00 |
| | 2834 | 8 TQRK 6 124 6 5 24 7 -116.29 61.69 -15.29 215.55 170.00 |
| | 2835 | |
| | 2836 | ---PARTON SHOWERS--- |
| | 2837 | |
| | 2838 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 2839 | 9 UBAR 94 141 4 6 11 16 -19.27 -6.00 314.16 310.83 -49.90 |
| | 2840 | 10 CONE 0 100 4 7 0 0 0.88 -0.47 0.53 1.13 0.00 |
| | 2841 | 11 UBARDBAR -2101 2 9 12 45 21 0.00 0.00 408.95 408.95 0.70 |
| | 2842 | 12 GLUON 21 2 9 13 46 47 8.42 0.19 140.64 140.89 0.75 |
| | 2843 | 13 GLUON 21 2 9 14 48 49 2.07 -1.20 14.47 14.68 0.75 |
| | 2844 | 14 DBAR -1 2 9 15 50 49 3.78 3.25 8.85 10.16 0.32 |
| | 2845 | 15 DQRK 1 2 9 16 51 50 3.65 2.24 9.47 10.40 0.32 |
| | 2846 | 16 GLUON 21 2 9 26 52 53 1.36 1.52 3.46 4.09 0.75 |
| | 2847 | 17 UQRK 94 142 5 6 19 21 2.85 2.07 -172.02 171.51 -13.73 |
| | 2848 | 18 CONE 0 100 5 8 0 0 -0.88 0.47 0.07 1.00 0.00 |
| | 2849 | 19 GLUON 21 2 17 20 54 55 -0.95 -0.97 -3.31 3.66 0.75 |
| | 2850 | 20 GLUON 21 2 17 21 56 57 -1.90 -1.10 -16.01 16.17 0.75 |
| | 2851 | 21 UD 2101 2 17 45 58 57 0.00 0.00 -708.66 708.66 1.04 |
| | 2852 | 22 TBAR 94 143 7 6 23 23 107.70 -63.75 156.89 263.01 170.00 |
| | 2853 | 23 TBAR -6 3 22 22 26 26 107.70 -63.75 156.89 263.01 170.00 |
| | 2854 | 24 TQRK 94 144 8 6 25 25 -124.12 59.82 -14.74 219.32 170.00 |
| | 2855 | 25 TQRK 6 3 24 24 37 37 -124.12 59.82 -14.74 219.32 170.00 |
| | 2856 | |
| | 2857 | ---HEAVY FLAVOUR DECAYS--- |
| | 2858 | |
| | 2859 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 2860 | 26 TBAR -6 155 22 37 27 29 107.70 -63.75 156.89 263.01 170.00 |
| | 2861 | 27 MU- 13 123 26 28 30 28 18.31 32.76 65.37 75.38 0.11 |
| | 2862 | 28 NU_MUBAR -14 124 26 27 31 27 80.30 -57.83 106.04 145.04 0.00 |
| | 2863 | 29 BBAR -5 124 26 26 32 26 9.09 -38.68 -14.52 42.60 4.95 |
| | 2864 | 30 MU- 13 1 27 26 0 0 17.82 31.88 63.62 73.36 0.11 |
| | 2865 | 31 NU_MUBAR -14 1 28 26 0 0 78.14 -56.28 103.19 141.14 0.00 |
| | 2866 | |
| | 2867 | ---PARTON SHOWERS--- |
| | 2868 | |
| | 2869 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 2870 | 32 BBAR 94 144 29 26 34 36 11.74 -39.36 -9.92 48.52 23.85 |
| | 2871 | 33 CONE 0 100 29 26 0 0 0.24 0.72 1.07 1.32 0.00 |
| | 2872 | 34 GLUON 21 2 32 35 59 60 -2.95 -0.95 -3.35 4.62 0.75 |
| | 2873 | 35 GLUON 21 2 32 36 61 62 -1.72 -1.41 -1.55 2.81 0.75 |
| | 2874 | 36 BBAR -5 2 32 44 63 62 16.41 -37.00 -5.02 41.08 4.95 |
| | 2875 | |
| | 2876 | ---HEAVY FLAVOUR DECAYS--- |
| | 2877 | |
| | 2878 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 2879 | 37 TQRK 6 155 24 19 38 40 -124.12 59.82 -14.74 219.32 170.00 |
| | 2880 | 38 NU_E 12 123 37 39 41 39 -96.15 66.72 23.37 119.34 0.00 |
| | 2881 | 39 E+ -11 124 37 38 42 38 6.38 13.33 -54.59 56.56 0.00 |
| | 2882 | 40 BQRK 5 124 37 37 43 37 -34.36 -20.23 16.48 43.43 4.95 |
| | 2883 | 41 NU_E 12 1 38 37 0 0 -96.15 66.72 23.37 119.34 0.00 |
| | 2884 | 42 E+ -11 1 39 37 0 0 6.38 13.33 -54.59 56.56 0.00 |
| | 2885 | |
| | 2886 | ---PARTON SHOWERS--- |
| | 2887 | |
| | 2888 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 2889 | 43 BQRK 94 144 40 37 44 44 -34.36 -20.23 16.48 43.43 4.95 |
| | 2890 | 44 BQRK 5 2 43 54 64 63 -34.36 -20.23 16.48 43.43 4.95 |
| | 2891 | |
| | 2892 | ---GLUON SPLITTING--- |
| | 2893 | |
| | 2894 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 2895 | 45 UBARDBAR -2101 161 9 65 85 58 0.01 0.00 279.95 279.95 0.64 |
| | 2896 | 46 UBAR -2 158 9 47 104 84 1.90 0.01 33.44 33.50 0.32 |
| | 2897 | 47 UQRK 2 158 9 69 86 46 3.96 0.11 64.98 65.11 0.32 |
| | 2898 | 48 DBAR -1 158 9 49 97 70 0.95 -0.68 7.08 7.18 0.32 |
| | 2899 | 49 DQRK 1 158 9 71 87 48 0.40 -0.05 2.32 2.38 0.32 |
| | 2900 | 50 DBAR -1 158 9 51 98 72 3.00 2.57 7.04 8.08 0.32 |
| | 2901 | 51 DQRK 1 158 9 52 88 50 3.65 2.24 9.47 10.40 0.32 |
| | 2902 | 52 DBAR -1 158 9 53 88 51 0.49 0.47 0.95 1.21 0.32 |
| | 2903 | 53 DQRK 1 158 9 73 89 52 0.79 0.96 2.29 2.62 0.32 |
| | 2904 | 54 DBAR -1 158 17 55 102 80 -0.23 -0.13 -0.54 0.68 0.32 |
| | 2905 | 55 DQRK 1 158 17 56 90 54 -0.62 -0.80 -2.35 2.58 0.32 |
| | 2906 | 56 DBAR -1 158 17 57 90 55 -1.18 -0.54 -8.28 8.38 0.32 |
| | 2907 | 57 DQRK 1 158 17 75 91 56 -0.34 -0.26 -5.03 5.06 0.32 |
| | 2908 | 58 UD 2101 162 17 45 96 68 0.00 0.00 -552.77 552.77 0.64 |
| | 2909 | 59 DBAR -1 158 32 60 99 74 -0.85 -0.40 -0.95 1.37 0.32 |
| | 2910 | 60 DQRK 1 158 32 61 92 59 -1.65 -0.34 -1.90 2.56 0.32 |
| | 2911 | 61 DBAR -1 158 32 62 92 60 -0.66 -0.74 -0.83 1.33 0.32 |
| | 2912 | 62 DQRK 1 158 32 77 93 61 -0.91 -0.59 -0.62 1.29 0.32 |
| | 2913 | 63 BBAR -5 158 32 64 101 78 14.03 -31.87 -4.37 35.44 4.95 |
| | 2914 | 64 BQRK 5 158 43 81 94 63 -24.17 -14.23 11.39 30.68 4.95 |
| | 2915 | 65 DBAR -1 159 9 66 85 45 0.06 0.00 30.61 30.61 0.32 |
| | 2916 | 66 DQRK 1 159 9 83 95 65 0.02 0.00 65.93 65.93 0.32 |
| | 2917 | 67 UBAR -2 159 17 68 100 76 0.00 0.00 -108.31 108.31 0.32 |
| | 2918 | 68 UQRK 2 159 17 58 96 67 -0.02 -0.02 -26.64 26.65 0.32 |
| | 2919 | 69 DBAR -1 159 9 70 86 47 0.44 -0.20 4.71 4.75 0.32 |
| | 2920 | 70 DQRK 1 159 9 48 97 69 2.01 0.04 32.91 32.97 0.32 |
| | 2921 | 71 SBAR -3 159 9 72 87 49 0.67 0.43 2.09 2.29 0.50 |
| | 2922 | 72 SQRK 3 159 9 50 98 71 0.55 0.00 2.95 3.04 0.50 |
| | 2923 | 73 UBAR -2 159 32 74 89 53 -0.35 -0.15 -0.36 0.61 0.32 |
| | 2924 | 74 UQRK 2 159 9 59 99 73 -0.02 0.04 0.09 0.33 0.32 |
| | 2925 | 75 SBAR -3 159 17 76 91 57 -0.10 -0.08 -15.37 15.37 0.50 |
| | 2926 | 76 SQRK 3 159 17 67 100 75 -0.26 -0.20 -8.28 8.30 0.50 |
| | 2927 | 77 SBAR -3 159 32 78 93 62 1.73 -3.90 -0.53 4.33 0.50 |
| | 2928 | 78 SQRK 3 159 32 63 101 77 0.49 -1.31 -0.22 1.50 0.50 |
| | 2929 | 79 DBAR -1 159 17 80 103 82 -0.22 -0.12 -0.18 0.45 0.32 |
| | 2930 | 80 DQRK 1 159 43 54 102 79 -3.20 -1.89 1.55 4.04 0.32 |
| | 2931 | 81 UBAR -2 159 17 82 94 64 -1.26 -0.74 0.58 1.61 0.32 |
| | 2932 | 82 UQRK 2 159 43 79 103 81 -5.60 -3.30 2.72 7.05 0.32 |
| | 2933 | 83 DBAR -1 159 9 84 95 66 0.07 0.00 27.33 27.33 0.32 |
| | 2934 | 84 DQRK 1 159 9 46 104 83 0.23 0.00 11.57 11.58 0.32 |
| | 2935 | |
| | 2936 | ---CLUSTER FORMATION--- |
| | 2937 | |
| | 2938 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 2939 | 85 CLUS 91 184 45 65 105 106 0.07 0.00 310.56 310.56 1.23 |
| | 2940 | 86 CLUS 91 183 47 69 107 108 4.40 -0.09 69.69 69.85 1.59 |
| | 2941 | 87 CLUS 91 183 49 71 109 110 1.07 0.38 4.41 4.67 1.03 |
| | 2942 | 88 CLUS 91 183 51 52 111 112 4.14 2.70 10.42 11.61 1.31 |
| | 2943 | 89 CLUS 91 183 53 73 113 114 0.44 0.80 1.92 3.24 2.44 |
| | 2944 | 90 CLUS 91 183 55 56 115 116 -1.80 -1.34 -10.63 10.96 1.48 |
| | 2945 | 91 CLUS 91 183 57 75 117 118 -0.44 -0.34 -20.39 20.43 1.09 |
| | 2946 | 92 CLUS 91 183 60 61 119 120 -2.31 -1.08 -2.73 3.89 1.09 |
| | 2947 | 93 CLUS 91 183 62 77 121 122 0.82 -4.49 -1.15 5.62 3.07 |
| | 2948 | 94 CLUS 91 183 64 81 123 123 -25.44 -14.98 11.97 32.29 5.28 |
| | 2949 | 95 CLUS 91 183 66 83 124 125 0.09 0.00 93.26 93.26 0.71 |
| | 2950 | 96 CLUS 91 185 68 58 126 127 -0.02 -0.02 -579.41 579.41 1.64 |
| | 2951 | 97 CLUS 91 183 70 48 128 129 2.97 -0.64 39.98 40.15 2.04 |
| | 2952 | 98 CLUS 91 183 72 50 130 131 3.54 2.57 9.99 11.12 2.17 |
| | 2953 | 99 CLUS 91 183 74 59 132 133 -0.87 -0.36 -0.86 1.71 1.13 |
| | 2954 | 100 CLUS 91 183 76 67 134 135 -0.26 -0.20 -116.59 116.61 2.24 |
| | 2955 | 101 CLUS 91 183 78 63 136 136 14.56 -33.17 -4.60 36.91 5.38 |
| | 2956 | 102 CLUS 91 183 80 54 137 138 -3.47 -2.02 1.02 4.76 2.34 |
| | 2957 | 103 CLUS 91 183 82 79 139 140 -5.81 -3.42 2.54 7.49 2.06 |
| | 2958 | 104 CLUS 91 183 84 46 141 142 2.13 0.01 45.01 45.08 1.04 |
| | 2959 | |
| | 2960 | ---CLUSTER DECAYS--- |
| | 2961 | |
| | 2962 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 2963 | 105 PBAR -2212 1 85 9 0 0 -0.13 0.09 215.09 215.09 0.94 |
| | 2964 | 106 PI+ 211 1 85 9 0 0 0.20 -0.09 95.47 95.47 0.14 |
| | 2965 | 107 OMEGA 223 197 86 9 143 145 2.33 -0.03 34.12 34.20 0.78 |
| | 2966 | 108 RHO+ 213 197 86 9 146 147 2.07 -0.06 35.58 35.65 0.77 |
| | 2967 | 109 PI0 111 1 87 9 0 0 0.14 0.05 0.57 0.60 0.14 |
| | 2968 | 110 K*0 313 197 87 9 148 149 0.93 0.34 3.84 4.07 0.90 |
| | 2969 | 111 PI0 111 1 88 9 0 0 2.48 1.51 6.44 7.07 0.14 |
| | 2970 | 112 OMEGA 223 197 88 9 150 151 1.66 1.19 3.98 4.54 0.78 |
| | 2971 | 113 P 2212 1 89 9 0 0 -0.35 0.36 0.89 1.39 0.94 |
| | 2972 | 114 DLTABR-- -2224 197 89 9 152 153 0.80 0.45 1.03 1.85 1.23 |
| | 2973 | 115 A_10 20113 197 90 17 154 155 -1.73 -1.30 -10.33 10.63 1.23 |
| | 2974 | 116 PI0 111 1 90 17 0 0 -0.06 -0.04 -0.30 0.33 0.14 |
| | 2975 | 117 PI- -211 1 91 17 0 0 -0.08 0.11 -12.23 12.23 0.14 |
| | 2976 | 118 K+ 321 1 91 17 0 0 -0.36 -0.44 -8.16 8.20 0.49 |
| | 2977 | 119 RHO- -213 197 92 32 156 157 -1.94 -1.07 -2.51 3.44 0.77 |
| | 2978 | 120 PI+ 211 1 92 32 0 0 -0.37 0.00 -0.22 0.45 0.14 |
| | 2979 | 121 KL_10 10313 197 93 32 158 159 1.17 -2.31 -1.07 3.22 1.57 |
| | 2980 | 122 ETAP 331 197 93 32 160 162 -0.35 -2.18 -0.08 2.41 0.96 |
| | 2981 | 123 B- -521 196 94 43 163 165 -25.44 -14.98 11.97 32.29 5.28 |
| | 2982 | 124 PI0 111 1 95 9 0 0 0.30 -0.06 25.24 25.24 0.14 |
| | 2983 | 125 PI0 111 1 95 9 0 0 -0.21 0.06 68.02 68.02 0.14 |
| | 2984 | 126 PI+ 211 1 96 17 0 0 0.04 0.14 -231.52 231.52 0.14 |
| | 2985 | 127 DELTA0 2114 197 96 17 166 167 -0.06 -0.15 -347.89 347.89 1.23 |
| | 2986 | 128 P 2212 1 97 9 0 0 0.84 -0.11 14.92 14.97 0.94 |
| | 2987 | 129 PBAR -2212 1 97 9 0 0 2.13 -0.53 25.06 25.17 0.94 |
| | 2988 | 130 ETA 221 197 98 9 168 170 0.59 0.27 2.25 2.40 0.55 |
| | 2989 | 131 K*_2BAR0 -315 197 98 9 171 172 2.95 2.30 7.74 8.72 1.43 |
| | 2990 | 132 PI0 111 1 99 9 0 0 -0.35 0.05 -0.95 1.02 0.14 |
| | 2991 | 133 PI+ 211 1 99 9 0 0 -0.52 -0.41 0.09 0.68 0.14 |
| | 2992 | 134 KBAR0 -311 197 100 17 173 173 0.04 -0.01 -17.14 17.15 0.50 |
| | 2993 | 135 PI_2- -10215 197 100 17 174 175 -0.30 -0.19 -99.44 99.46 1.67 |
| | 2994 | 136 B_S0 531 200 101 32 176 176 14.56 -33.17 -4.60 36.91 5.38 |
| | 2995 | 137 HL_10 10223 197 102 43 177 178 -3.20 -1.92 1.24 4.10 1.17 |
| | 2996 | 138 ETA 221 197 102 43 179 181 -0.28 -0.10 -0.22 0.66 0.55 |
| | 2997 | 139 A_20 115 197 103 43 182 184 -2.96 -1.35 1.04 3.66 1.32 |
| | 2998 | 140 PI+ 211 1 103 43 0 0 -2.85 -2.07 1.50 3.84 0.14 |
| | 2999 | 141 PI0 111 1 104 9 0 0 0.66 0.06 16.64 16.65 0.14 |
| | 3000 | 142 RHO- -213 197 104 9 185 186 1.47 -0.05 28.37 28.42 0.77 |
| | 3001 | |
| | 3002 | ---STRONG HADRON DECAYS--- |
| | 3003 | |
| | 3004 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3005 | 143 PI+ 211 1 107 9 0 0 1.90 -0.02 24.27 24.35 0.14 |
| | 3006 | 144 PI- -211 1 107 9 0 0 0.32 0.00 6.77 6.78 0.14 |
| | 3007 | 145 PI0 111 1 107 9 0 0 0.11 -0.02 3.07 3.08 0.14 |
| | 3008 | 146 PI+ 211 1 108 9 0 0 1.80 0.19 29.01 29.07 0.14 |
| | 3009 | 147 PI0 111 1 108 9 0 0 0.27 -0.25 6.57 6.58 0.14 |
| | 3010 | 148 K0 311 198 110 9 187 187 0.65 0.06 3.19 3.29 0.50 |
| | 3011 | 149 PI0 111 1 110 9 0 0 0.28 0.27 0.65 0.77 0.14 |
| | 3012 | 150 PI0 111 1 112 9 0 0 1.33 1.12 3.73 4.12 0.14 |
| | 3013 | 151 GAMMA 22 1 112 9 0 0 0.34 0.07 0.25 0.42 0.00 |
| | 3014 | 152 PBAR -2212 1 114 9 0 0 0.75 0.24 1.02 1.59 0.94 |
| | 3015 | 153 PI- -211 1 114 9 0 0 0.05 0.21 0.01 0.25 0.14 |
| | 3016 | 154 RHO+ 213 198 115 17 188 189 -1.57 -0.83 -8.84 9.05 0.77 |
| | 3017 | 155 PI- -211 1 115 17 0 0 -0.16 -0.47 -1.49 1.58 0.14 |
| | 3018 | 156 PI- -211 1 119 32 0 0 -0.65 -0.64 -1.38 1.66 0.14 |
| | 3019 | 157 PI0 111 1 119 32 0 0 -1.29 -0.43 -1.12 1.77 0.14 |
| | 3020 | 158 K+ 321 1 121 32 0 0 0.56 -0.88 0.04 1.15 0.49 |
| | 3021 | 159 RHO- -213 198 121 32 190 191 0.61 -1.43 -1.11 2.06 0.77 |
| | 3022 | 160 PI+ 211 1 122 32 0 0 -0.15 -0.86 0.05 0.89 0.14 |
| | 3023 | 161 PI- -211 1 122 32 0 0 -0.07 -0.48 -0.08 0.51 0.14 |
| | 3024 | 162 ETA 221 198 122 32 192 193 -0.13 -0.84 -0.05 1.01 0.55 |
| | 3025 | 163 RHO0 113 198 123 43 194 195 -18.44 -9.34 6.79 21.77 0.77 |
| | 3026 | 164 E- 11 1 123 43 0 0 -6.49 -5.26 5.27 9.88 0.00 |
| | 3027 | 165 NU_EBAR -12 1 123 43 0 0 -0.50 -0.38 -0.09 0.63 0.00 |
| | 3028 | 166 P 2212 1 127 17 0 0 0.09 -0.11 -219.33 219.33 0.94 |
| | 3029 | 167 PI- -211 1 127 17 0 0 -0.15 -0.05 -128.56 128.56 0.14 |
| | 3030 | 168 PI0 111 1 130 9 0 0 0.07 0.07 0.80 0.82 0.14 |
| | 3031 | 169 PI0 111 1 130 9 0 0 0.21 0.13 0.47 0.55 0.14 |
| | 3032 | 170 PI0 111 1 130 9 0 0 0.31 0.07 0.98 1.04 0.14 |
| | 3033 | 171 K- -321 1 131 9 0 0 2.36 1.08 5.22 5.85 0.49 |
| | 3034 | 172 PI+ 211 1 131 9 0 0 0.59 1.22 2.53 2.87 0.14 |
| | 3035 | 173 K_S0 310 198 134 17 196 197 0.04 -0.01 -17.14 17.15 0.50 |
| | 3036 | 174 F_2 225 198 135 17 198 199 -0.33 -0.32 -95.89 95.90 1.27 |
| | 3037 | 175 PI- -211 1 135 17 0 0 0.03 0.12 -3.56 3.56 0.14 |
| | 3038 | 176 B_SBAR0 -531 199 136 32 207 208 14.56 -33.17 -4.60 36.91 5.38 |
| | 3039 | 177 RHO+ 213 198 137 43 200 201 -2.29 -1.73 0.99 3.13 0.77 |
| | 3040 | 178 PI- -211 1 137 43 0 0 -0.90 -0.19 0.24 0.96 0.14 |
| | 3041 | 179 PI0 111 1 138 43 0 0 0.01 0.05 0.02 0.15 0.14 |
| | 3042 | 180 PI0 111 1 138 43 0 0 -0.07 -0.10 -0.06 0.19 0.14 |
| | 3043 | 181 PI0 111 1 138 43 0 0 -0.22 -0.05 -0.18 0.32 0.14 |
| | 3044 | 182 OMEGA 223 198 139 43 202 204 -1.92 -0.63 0.73 2.28 0.78 |
| | 3045 | 183 PI+ 211 1 139 43 0 0 -0.66 -0.32 0.05 0.75 0.14 |
| | 3046 | 184 PI- -211 1 139 43 0 0 -0.38 -0.40 0.26 0.63 0.14 |
| | 3047 | 185 PI- -211 1 142 9 0 0 0.68 -0.38 13.27 13.29 0.14 |
| | 3048 | 186 PI0 111 1 142 9 0 0 0.79 0.33 15.11 15.13 0.14 |
| | 3049 | 187 K_S0 310 198 148 9 205 206 0.65 0.06 3.19 3.29 0.50 |
| | 3050 | 188 PI+ 211 1 154 17 0 0 -1.45 -0.73 -8.47 8.62 0.14 |
| | 3051 | 189 PI0 111 1 154 17 0 0 -0.13 -0.10 -0.37 0.43 0.14 |
| | 3052 | 190 PI- -211 1 159 32 0 0 0.68 -1.24 -1.13 1.82 0.14 |
| | 3053 | 191 PI0 111 1 159 32 0 0 -0.06 -0.19 0.02 0.24 0.14 |
| | 3054 | 192 GAMMA 22 1 162 32 0 0 -0.31 -0.62 -0.15 0.71 0.00 |
| | 3055 | 193 GAMMA 22 1 162 32 0 0 0.18 -0.22 0.10 0.30 0.00 |
| | 3056 | 194 PI+ 211 1 163 43 0 0 -16.47 -8.12 6.03 19.32 0.14 |
| | 3057 | 195 PI- -211 1 163 43 0 0 -1.98 -1.22 0.76 2.45 0.14 |
| | 3058 | 196 PI0 111 1 173 17 0 0 0.14 0.16 -6.36 6.37 0.14 |
| | 3059 | 197 PI0 111 1 173 17 0 0 -0.10 -0.16 -10.78 10.78 0.14 |
| | 3060 | 198 PI0 111 1 174 17 0 0 -0.61 -0.52 -38.85 38.86 0.14 |
| | 3061 | 199 PI0 111 1 174 17 0 0 0.27 0.20 -57.03 57.04 0.14 |
| | 3062 | 200 PI+ 211 1 177 43 0 0 -1.01 -0.34 0.30 1.11 0.14 |
| | 3063 | 201 PI0 111 1 177 43 0 0 -1.29 -1.39 0.70 2.02 0.14 |
| | 3064 | 202 PI+ 211 1 182 43 0 0 -0.30 -0.02 0.08 0.34 0.14 |
| | 3065 | 203 PI- -211 1 182 43 0 0 -0.30 -0.13 0.36 0.50 0.14 |
| | 3066 | 204 PI0 111 1 182 43 0 0 -1.32 -0.48 0.29 1.44 0.14 |
| | 3067 | 205 PI0 111 1 187 9 0 0 0.51 -0.06 1.56 1.65 0.14 |
| | 3068 | 206 PI0 111 1 187 9 0 0 0.14 0.12 1.63 1.64 0.14 |
| | 3069 | |
| | 3070 | ---HEAVY FLAVOUR DECAYS--- |
| | 3071 | |
| | 3072 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3073 | 207 BQRK 5 155 176 208 209 211 13.20 -30.08 -4.17 33.47 4.88 |
| | 3074 | 208 SBAR -3 125 176 211 212 211 1.35 -3.09 -0.43 3.43 0.50 |
| | 3075 | 209 CQRK 4 123 207 210 213 210 2.30 -5.94 -0.61 6.59 1.55 |
| | 3076 | 210 CBAR -4 124 207 209 215 209 3.58 -8.37 -1.74 9.40 1.55 |
| | 3077 | 211 SQRK 3 124 207 207 217 207 7.33 -15.77 -1.82 17.49 0.50 |
| | 3078 | 212 SBAR -3 160 208 221 223 221 1.35 -3.09 -0.43 3.43 0.50 |
| | 3079 | |
| | 3080 | ---PARTON SHOWERS--- |
| | 3081 | |
| | 3082 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3083 | 213 CQRK 94 143 209 207 214 214 2.30 -5.94 -0.61 6.59 1.55 |
| | 3084 | 214 CQRK 4 2 213 216 219 216 2.30 -5.94 -0.61 6.59 1.55 |
| | 3085 | 215 CBAR 94 144 210 207 216 216 3.58 -8.37 -1.74 9.40 1.55 |
| | 3086 | 216 CBAR -4 2 215 219 220 219 3.58 -8.37 -1.74 9.40 1.55 |
| | 3087 | 217 SQRK 94 144 211 207 218 218 7.33 -15.77 -1.82 17.49 0.50 |
| | 3088 | 218 SQRK 3 2 217 212 221 212 7.33 -15.77 -1.82 17.49 0.50 |
| | 3089 | |
| | 3090 | ---GLUON SPLITTING--- |
| | 3091 | |
| | 3092 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3093 | 219 CQRK 4 158 213 220 222 220 2.30 -5.94 -0.61 6.59 1.55 |
| | 3094 | 220 CBAR -4 158 215 219 222 219 3.58 -8.37 -1.74 9.40 1.55 |
| | 3095 | 221 SQRK 3 158 217 212 223 212 7.33 -15.77 -1.82 17.49 0.50 |
| | 3096 | |
| | 3097 | ---CLUSTER FORMATION--- |
| | 3098 | |
| | 3099 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3100 | 222 CLUS 91 183 219 220 224 224 4.87 -12.18 -2.12 13.62 2.98 |
| | 3101 | 223 CLUS 91 183 221 212 225 226 9.69 -20.99 -2.48 23.29 1.37 |
| | 3102 | |
| | 3103 | ---CLUSTER DECAYS--- |
| | 3104 | |
| | 3105 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3106 | 224 ETA_C 441 199 222 213 227 229 4.87 -12.18 -2.12 13.62 2.98 |
| | 3107 | 225 K- -321 1 223 217 0 0 8.22 -17.67 -2.03 19.60 0.49 |
| | 3108 | 226 K+ 321 1 223 217 0 0 1.47 -3.31 -0.45 3.69 0.49 |
| | 3109 | |
| | 3110 | ---HEAVY FLAVOUR DECAYS--- |
| | 3111 | |
| | 3112 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3113 | 227 GLUON 21 123 224 229 230 228 2.59 -4.45 -1.11 5.32 0.75 |
| | 3114 | 228 GLUON 21 124 224 227 232 229 0.84 -4.20 -0.51 4.38 0.75 |
| | 3115 | 229 GLUON 21 124 224 228 234 227 1.44 -3.53 -0.50 3.92 0.75 |
| | 3116 | |
| | 3117 | ---PARTON SHOWERS--- |
| | 3118 | |
| | 3119 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3120 | 230 GLUON 94 143 227 224 231 231 2.59 -4.45 -1.11 5.32 0.75 |
| | 3121 | 231 GLUON 21 2 230 235 236 237 2.59 -4.45 -1.11 5.32 0.75 |
| | 3122 | 232 GLUON 94 144 228 224 233 233 0.84 -4.20 -0.51 4.38 0.75 |
| | 3123 | 233 GLUON 21 2 232 236 238 239 0.84 -4.20 -0.51 4.38 0.75 |
| | 3124 | 234 GLUON 94 144 229 224 235 235 1.44 -3.53 -0.50 3.92 0.75 |
| | 3125 | 235 GLUON 21 2 234 238 240 241 1.44 -3.53 -0.50 3.92 0.75 |
| | 3126 | |
| | 3127 | ---GLUON SPLITTING--- |
| | 3128 | |
| | 3129 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3130 | 236 DBAR -1 158 230 237 243 239 1.65 -2.62 -0.82 3.22 0.32 |
| | 3131 | 237 DQRK 1 158 230 240 242 236 0.95 -1.83 -0.29 2.10 0.32 |
| | 3132 | 238 DBAR -1 158 232 239 244 241 0.66 -3.17 -0.34 3.27 0.32 |
| | 3133 | 239 DQRK 1 158 232 236 243 238 0.18 -1.03 -0.17 1.11 0.32 |
| | 3134 | 240 UBAR -2 158 234 241 242 237 0.65 -2.08 -0.24 2.22 0.32 |
| | 3135 | 241 UQRK 2 158 234 238 244 240 0.79 -1.45 -0.26 1.70 0.32 |
| | 3136 | |
| | 3137 | ---CLUSTER FORMATION--- |
| | 3138 | |
| | 3139 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3140 | 242 CLUS 91 183 237 240 245 246 1.60 -3.90 -0.53 4.32 0.74 |
| | 3141 | 243 CLUS 91 183 239 236 247 248 1.82 -3.65 -0.98 4.33 1.03 |
| | 3142 | 244 CLUS 91 183 241 238 249 250 1.45 -4.62 -0.60 4.98 0.96 |
| | 3143 | |
| | 3144 | ---CLUSTER DECAYS--- |
| | 3145 | |
| | 3146 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3147 | 245 PI- -211 1 242 230 0 0 1.53 -3.79 -0.46 4.11 0.14 |
| | 3148 | 246 PI0 111 1 242 230 0 0 0.06 -0.12 -0.07 0.20 0.14 |
| | 3149 | 247 PI0 111 1 243 232 0 0 0.52 -0.39 0.03 0.66 0.14 |
| | 3150 | 248 PI0 111 1 243 232 0 0 1.30 -3.27 -1.01 3.66 0.14 |
| | 3151 | 249 PI0 111 1 244 234 0 0 1.02 -3.98 -0.74 4.18 0.14 |
| | 3152 | 250 PI+ 211 1 244 234 0 0 0.43 -0.64 0.14 0.80 0.14 |
| | 3153 | |
| | 3154 | OUTPUT ON ELEMENTARY PROCESS |
| | 3155 | |
| | 3156 | NUMBER OF EVENTS = 1000 |
| | 3157 | NUMBER OF WEIGHTS = 14518 |
| | 3158 | MEAN VALUE OF WGT = 4.4894E-03 |
| | 3159 | RMS SPREAD IN WGT = 9.2221E-03 |
| | 3160 | ACTUAL MAX WEIGHT = 6.1048E-02 |
| | 3161 | ASSUMED MAX WEIGHT = 6.6571E-02 |
| | 3162 | |
| | 3163 | PROCESS CODE IPROC = 11706 |
| | 3164 | CROSS SECTION (PB) = 4.489 |
| | 3165 | ERROR IN C-S (PB) = 7.6538E-02 |
| | 3166 | EFFICIENCY PERCENT = 6.744 |
| | 3167 | |
| | 3168 | ----------------------------------------------------------------------- |
| | 3169 | |
| | 3170 | ****** 22. GUIDE TO SAMPLE OUTPUT ****** |
| | 3171 | |
| | 3172 | |
| | 3173 | After listing the more important input parameter values, the program |
| | 3174 | prints the message |
| | 3175 | |
| | 3176 | NO EVENTS WILL BE WRITTEN TO DISK |
| | 3177 | |
| | 3178 | to remind the user that LWEVT=0 for this run. Since BBbar oscillation |
| | 3179 | is enabled (MIXING=.TRUE.), the relevant parameters are printed: |
| | 3180 | |
| | 3181 | B_d: Delt-M/Gam =0.7000 Delt-Gam/2*Gam =0.0000 |
| | 3182 | B_s: Delt-M/Gam = 10.00 Delt-Gam/2*Gam =0.2000 |
| | 3183 | |
| | 3184 | The messages |
| | 3185 | |
| | 3186 | PDFLIB NOT USED FOR BEAM 1 |
| | 3187 | PDFLIB NOT USED FOR BEAM 2 |
| | 3188 | |
| | 3189 | indicating that the CERN PDFLIB structure function library will not |
| | 3190 | be used (MODPDF<0). Next the particle property and decay tables are |
| | 3191 | checked for consistency. The messages |
| | 3192 | |
| | 3193 | Line, 565 decay: LMBDA_C+ --> XI*0 K*+ |
| | 3194 | is kinematically not allowed, Min-Mout= -0.139 |
| | 3195 | LMBDA_C+: BR sum = 0.97800 |
| | 3196 | Rescaling to 1 |
| | 3197 | |
| | 3198 | Line, 990 decay: LMBDA_C- --> XI*BAR K*- |
| | 3199 | is kinematically not allowed, Min-Mout= -0.139 |
| | 3200 | LMBDA_C-: BR sum = 0.97800 |
| | 3201 | Rescaling to 1 |
| | 3202 | |
| | 3203 | indicate that some user-modified decay modes are impossible and will |
| | 3204 | be ignored. The default particle data table was modified by calling |
| | 3205 | HWUSTA('PI0 ') to suppress pi0 decays, so we get the message |
| | 3206 | |
| | 3207 | PARTICLE TYPE 21=PI0 SET STABLE |
| | 3208 | |
| | 3209 | Next the program searches for the maximum weight, i.e. the maximum |
| | 3210 | cross section in the available phase space, as implied by the default |
| | 3211 | value WGTMAX=0. The parameters |
| | 3212 | |
| | 3213 | MIN P-TRAN FOR 2->2 = 10.0000 |
| | 3214 | MAX P-TRAN FOR 2->2 = 900.0002 |
| | 3215 | with |
| | 3216 | PROCESS CODE = 11706 |
| | 3217 | |
| | 3218 | mean that the transverse momentum of the t quark in the QCD 2->2 hard |
| | 3219 | subprocesses is required to be greater than 10 GeV/c. After this |
| | 3220 | search, the estimated total cross section of relevant subprocesses in |
| | 3221 | this region of phase space is printed, together with the anticipated |
| | 3222 | efficiency of subprocess generation (i.e. average/maximum weight): |
| | 3223 | |
| | 3224 | CROSS SECTION (PB) = 4.537 |
| | 3225 | ERROR IN C-S (PB) = 0.2087 |
| | 3226 | EFFICIENCY PERCENT = 6.816 |
| | 3227 | |
| | 3228 | Since the print parameter was MAXPR=0, no events were printed by |
| | 3229 | default, but the user analysis routine HWANAL called HWUEPR to print |
| | 3230 | the first "interesting" event. The event heading |
| | 3231 | |
| | 3232 | EVENT 39: 900.00 GEV/C PBAR ON 900.00 GEV/C P PROCESS: 11706 |
| | 3233 | |
| | 3234 | SEEDS: 875163092 & 655954870 STATUS: 100 ERROR: 0 WEIGHT: 0.4537E-02 |
| | 3235 | |
| | 3236 | |
| | 3237 | tells us the beam and target, the random number seeds at the start of |
| | 3238 | the event and the process code IPROC. The status 100 means a complete |
| | 3239 | event was generated and the zero error code means no problems were |
| | 3240 | encountered. Since NOWGT=.TRUE. (unweighted event generation), each |
| | 3241 | event has the mean weight computed earlier. |
| | 3242 | |
| | 3243 | Next come the contents of COMMON/HEPEVT/ and related quantities. The |
| | 3244 | print parameter for vertex information has been set PRVTX=.FALSE. and |
| | 3245 | so no space-time information is printed. The various parts of this |
| | 3246 | particular event are located as follows: |
| | 3247 | |
| | 3248 | +---------+--------------------------------------+ |
| | 3249 | | Entry | Description | |
| | 3250 | +---------+--------------------------------------+ |
| | 3251 | | 1- 3 | Initial state | |
| | 3252 | | 4- 8 | Hard subprocess: u+ubar -> t+tbar | |
| | 3253 | | 9- 25 | Parton showers | |
| | 3254 | | 26- 44 | Top decays and subsequent showers | |
| | 3255 | | 45- 84 | Gluon splitting | |
| | 3256 | | 85-104 | Cluster formation | |
| | 3257 | | 105-206 | Cluster and hadron decays | |
| | 3258 | | 207-218 | Weak decay of B_sbar and showers | |
| | 3259 | | 219-226 | Hadronization of B_sbar products | |
| | 3260 | | 227-235 | 3-gluon decay of eta_c | |
| | 3261 | | 236-250 | Hadronization of eta_c products | |
| | 3262 | +---------+--------------------------------------+ |
| | 3263 | |
| | 3264 | We discuss each part in turn. |
| | 3265 | |
| | 3266 | ---INITIAL STATE--- |
| | 3267 | |
| | 3268 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3269 | 1 PBAR -2212 101 0 0 0 0 0.00 0.00 900.00 900.00 0.94 |
| | 3270 | 2 P 2212 102 0 0 0 0 0.00 0.00 -900.00 900.00 0.94 |
| | 3271 | 3 CMF 0 103 1 2 0 0 0.00 0.00 0.00 1800.00 1800.00 |
| | 3272 | |
| | 3273 | CMF represents the overall centre of mass of the initial state. The |
| | 3274 | 'mother' MOi=JMOHEP(i,IHEP) & 'daughter' DAi=JDAHEP(i,IHEP) pointers |
| | 3275 | are set to zero for these entries. |
| | 3276 | |
| | 3277 | ---HARD SUBPROCESS--- |
| | 3278 | |
| | 3279 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3280 | 4 UBAR -2 121 6 7 9 5 0.00 0.00 312.09 312.09 0.32 |
| | 3281 | 5 UQRK 2 122 6 4 17 8 0.00 0.00 -169.95 169.95 0.32 |
| | 3282 | 6 HARD 0 120 4 5 7 8 -16.42 -3.93 142.14 482.34 460.61 |
| | 3283 | 7 TBAR -6 123 6 8 22 4 116.29 -61.69 157.43 266.49 170.00 |
| | 3284 | 8 TQRK 6 124 6 5 24 7 -116.29 61.69 -15.29 215.55 170.00 |
| | 3285 | |
| | 3286 | HARD is the hard subprocess centre of mass. Its mother and daughter |
| | 3287 | pointers give the locations of the incoming and outgoing partons. The |
| | 3288 | status codes 121-124 correspond to the hard subprocess partons 1-4. |
| | 3289 | The first mother pointers show the location of the hard c.m., and the |
| | 3290 | second mother of each parton is the 'colour mother', as explained |
| | 3291 | above. Thus the colours of partons 1234 are connected to 3142 respt., |
| | 3292 | corresponding to process IHPRO=12. Likewise,the first daughter points |
| | 3293 | to the associated jet but the second daughter is the colour daughter, |
| | 3294 | i.e. the parton to which this one's anticolour is connected. Thus the |
| | 3295 | anticolour connections of 1234 in this case are to 2413. The colour |
| | 3296 | diagram is |
| | 3297 | |
| | 3298 | (ubar)1 --<--+ +--<-- 3(tbar) |
| | 3299 | \___/ |
| | 3300 | ___ |
| | 3301 | / \ |
| | 3302 | (u)2 -->--+ +-->-- 4(t) |
| | 3303 | |
| | 3304 | Note that in specifying the colour connections all lines are regarded |
| | 3305 | as outgoing, and that since antiquarks carry no colour MO2 is in that |
| | 3306 | case used for the flavour connection (similarly with DA2 for quarks). |
| | 3307 | Gluon radiation from the initial ubar will be limited by interference |
| | 3308 | with the tbar and vice-versa, that from the incoming u by the t and |
| | 3309 | vice-versa. At this stage, the momenta and masses of the partons are |
| | 3310 | the raw on-shell values generated before QCD radiative corrections, |
| | 3311 | but HARD has been updated to give the true hard subprocess momentum |
| | 3312 | after initial- and final-state parton branching. |
| | 3313 | |
| | 3314 | ---PARTON SHOWERS--- |
| | 3315 | |
| | 3316 | The QCD cascade from each hard parton is generated in sequence. First |
| | 3317 | there is a jet entry (IDHEP=94) giving the total jet momentum, mass |
| | 3318 | and flavour. For initial-state jets the mass represents -|q**2|**1/2 |
| | 3319 | for the virtual parton entering the hard subprocess. MO1 gives the |
| | 3320 | parent hard parton and MO2 the hard centre-of-mass. DO1 and DO2 point |
| | 3321 | to the first and last parton in the jet after perturbative branching. |
| | 3322 | If branching occurs, the next entry (CONE) is a lightlike 4-vector |
| | 3323 | defining the radiation cone and the orientation of the radiation |
| | 3324 | pattern. |
| | 3325 | |
| | 3326 | The partons in the jet (with ISTHEP set to 2 by gluon splitting sub- |
| | 3327 | routine HWCGSP) have their colour and anticolour connections given |
| | 3328 | by MO2 and DA2 respectively, as described for the hard subprocess. |
| | 3329 | For an incoming jet, the remnants of the incoming hadrons (IHEP=11,21 |
| | 3330 | here) also have ISTHEP=2. The ubar jet is: |
| | 3331 | |
| | 3332 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3333 | 9 UBAR 94 141 4 6 11 16 -19.27 -6.00 314.16 310.83 -49.90 |
| | 3334 | 10 CONE 0 100 4 7 0 0 0.88 -0.47 0.53 1.13 0.00 |
| | 3335 | 11 UBARDBAR -2101 2 9 12 45 21 0.00 0.00 408.95 408.95 0.70 |
| | 3336 | 12 GLUON 21 2 9 13 46 47 8.42 0.19 140.64 140.89 0.75 |
| | 3337 | 13 GLUON 21 2 9 14 48 49 2.07 -1.20 14.47 14.68 0.75 |
| | 3338 | 14 DBAR -1 2 9 15 50 49 3.78 3.25 8.85 10.16 0.32 |
| | 3339 | 15 DQRK 1 2 9 16 51 50 3.65 2.24 9.47 10.40 0.32 |
| | 3340 | 16 GLUON 21 2 9 26 52 53 1.36 1.52 3.46 4.09 0.75 |
| | 3341 | |
| | 3342 | and similarly for the u jet (IHEP=17-21). The produced t and tbar are |
| | 3343 | so slow in the subprocess c.o.m. frame that they do not radiate any |
| | 3344 | resolvable gluons. After any showering, they're given status ISTHEP=3 |
| | 3345 | and copied with ISTHEP=155 retaining the colour connection labels for |
| | 3346 | the decay processes. In this event both top decays are leptonic: |
| | 3347 | |
| | 3348 | ---HEAVY FLAVOUR DECAYS--- |
| | 3349 | |
| | 3350 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3351 | 26 TBAR -6 155 22 37 27 29 107.70 -63.75 156.89 263.01 170.00 |
| | 3352 | 27 MU- 13 123 26 28 30 28 18.31 32.76 65.37 75.38 0.11 |
| | 3353 | 28 NU_MUBAR -14 124 26 27 31 27 80.30 -57.83 106.04 145.04 0.00 |
| | 3354 | 29 BBAR -5 124 26 26 32 26 9.09 -38.68 -14.52 42.60 4.95 |
| | 3355 | 30 MU- 13 1 27 26 0 0 17.82 31.88 63.62 73.36 0.11 |
| | 3356 | 31 NU_MUBAR -14 1 28 26 0 0 78.14 -56.28 103.19 141.14 0.00 |
| | 3357 | |
| | 3358 | 37 TQRK 6 155 24 19 38 40 -124.12 59.82 -14.74 219.32 170.00 |
| | 3359 | 38 NU_E 12 123 37 39 41 39 -96.15 66.72 23.37 119.34 0.00 |
| | 3360 | 39 E+ -11 124 37 38 42 38 6.38 13.33 -54.59 56.56 0.00 |
| | 3361 | 40 BQRK 5 124 37 37 43 37 -34.36 -20.23 16.48 43.43 4.95 |
| | 3362 | 41 NU_E 12 1 38 37 0 0 -96.15 66.72 23.37 119.34 0.00 |
| | 3363 | 42 E+ -11 1 39 37 0 0 6.38 13.33 -54.59 56.56 0.00 |
| | 3364 | |
| | 3365 | ---PARTON SHOWERS--- |
| | 3366 | |
| | 3367 | After the tbar decay, the resulting bbar radiates 2 gluons: |
| | 3368 | |
| | 3369 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3370 | 32 BBAR 94 144 29 26 34 36 11.74 -39.36 -9.92 48.52 23.85 |
| | 3371 | 33 CONE 0 100 29 26 0 0 0.24 0.72 1.07 1.32 0.00 |
| | 3372 | 34 GLUON 21 2 32 35 59 60 -2.95 -0.95 -3.35 4.62 0.75 |
| | 3373 | 35 GLUON 21 2 32 36 61 62 -1.72 -1.41 -1.55 2.81 0.75 |
| | 3374 | 36 BBAR -5 2 32 44 63 62 16.41 -37.00 -5.02 41.08 4.95 |
| | 3375 | |
| | 3376 | but the b quark from the t decay does not radiate. If the decays had |
| | 3377 | been hadronic, the quarks from the virtual W decay would also radiate |
| | 3378 | in general. |
| | 3379 | |
| | 3380 | ---GLUON SPLITTING--- |
| | 3381 | |
| | 3382 | As the first step in the cluster hadronization model, any gluons in |
| | 3383 | the jets are split into light quark-antiquark pairs. The flavours of |
| | 3384 | the pairs are chosen at random amongst those allowed by kinematics. |
| | 3385 | The colour connections are remade accordingly. |
| | 3386 | |
| | 3387 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3388 | 45 UBARDBAR -2101 161 9 65 85 58 0.01 0.00 279.95 279.95 0.64 |
| | 3389 | 46 UBAR -2 158 9 47 104 84 1.90 0.01 33.44 33.50 0.32 |
| | 3390 | 47 UQRK 2 158 9 69 86 46 3.96 0.11 64.98 65.11 0.32 |
| | 3391 | 48 DBAR -1 158 9 49 97 70 0.95 -0.68 7.08 7.18 0.32 |
| | 3392 | 49 DQRK 1 158 9 71 87 48 0.40 -0.05 2.32 2.38 0.32 |
| | 3393 | ....... |
| | 3394 | 63 BBAR -5 158 32 64 101 78 14.03 -31.87 -4.37 35.44 4.95 |
| | 3395 | 64 BQRK 5 158 43 81 94 63 -24.17 -14.23 11.39 30.68 4.95 |
| | 3396 | |
| | 3397 | Each quark (or antidiquark) is combined with its colour mother anti- |
| | 3398 | quark (or diquark) to make a cluster with the sum of their 4-momenta. |
| | 3399 | All non-beam clusters with masses above the maximum are split by |
| | 3400 | creating new quark-antiquark pairs with ISTHEP=159 (10 such pairs in |
| | 3401 | this event). |
| | 3402 | |
| | 3403 | 65 DBAR -1 159 9 66 85 45 0.06 0.00 30.61 30.61 0.32 |
| | 3404 | 66 DQRK 1 159 9 83 95 65 0.02 0.00 65.93 65.93 0.32 |
| | 3405 | ....... |
| | 3406 | 83 DBAR -1 159 9 84 95 66 0.07 0.00 27.33 27.33 0.32 |
| | 3407 | 84 DQRK 1 159 9 46 104 83 0.23 0.00 11.57 11.58 0.32 |
| | 3408 | |
| | 3409 | ---CLUSTER FORMATION--- |
| | 3410 | |
| | 3411 | Next the clusters themselves are listed. The mothers of a cluster are |
| | 3412 | the partons from which it is made, and the daughters are the primary |
| | 3413 | hadrons into which it decays. |
| | 3414 | |
| | 3415 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3416 | 85 CLUS 91 184 45 65 105 106 0.07 0.00 310.56 310.56 1.23 |
| | 3417 | 86 CLUS 91 183 47 69 107 108 4.40 -0.09 69.69 69.85 1.59 |
| | 3418 | ....... |
| | 3419 | 103 CLUS 91 183 82 79 139 140 -5.81 -3.42 2.54 7.49 2.06 |
| | 3420 | 104 CLUS 91 183 84 46 141 142 2.13 0.01 45.01 45.08 1.04 |
| | 3421 | |
| | 3422 | ---CLUSTER DECAYS--- |
| | 3423 | |
| | 3424 | The clusters, including the b-flavoured clusters 94 and 101, now |
| | 3425 | decay, usually into pairs of hadrons chosen according to the density |
| | 3426 | of states. Sometimes single-hadron decays occur, with transfer of |
| | 3427 | momentum to a neighbouring cluster, if there is insufficient phase |
| | 3428 | space for two-body decay. Note that cluster 94 actually did a 1-body |
| | 3429 | decay into a B- (IHEP=123, ISTHEP=196). Hadrons with ISTHEP=1 are |
| | 3430 | stable. ISTHEP=200 indicates a neutral B meson which may undergo |
| | 3431 | flavour oscillation. |
| | 3432 | |
| | 3433 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3434 | 105 PBAR -2212 1 85 9 0 0 -0.13 0.09 215.09 215.09 0.94 |
| | 3435 | 106 PI+ 211 1 85 9 0 0 0.20 -0.09 95.47 95.47 0.14 |
| | 3436 | 107 OMEGA 223 197 86 9 143 145 2.33 -0.03 34.12 34.20 0.78 |
| | 3437 | 108 RHO+ 213 197 86 9 146 147 2.07 -0.06 35.58 35.65 0.77 |
| | 3438 | ....... |
| | 3439 | 123 B- -521 196 94 43 163 165 -25.44 -14.98 11.97 32.29 5.28 |
| | 3440 | ....... |
| | 3441 | 136 B_S0 531 200 101 32 176 176 14.56 -33.17 -4.60 36.91 5.38 |
| | 3442 | ....... |
| | 3443 | 141 PI0 111 1 104 9 0 0 0.66 0.06 16.64 16.65 0.14 |
| | 3444 | 142 RHO- -213 197 104 9 185 186 1.47 -0.05 28.37 28.42 0.77 |
| | 3445 | |
| | 3446 | ---STRONG HADRON DECAYS--- |
| | 3447 | |
| | 3448 | The unstable hadrons decay according to decay tables. Remember that |
| | 3449 | the pi0 was set stable in the initialization phase. For heavy (b,c) |
| | 3450 | quarks, partonic or direct hadronic decays may occur. In this event |
| | 3451 | the B- does a b -> u directly to rho0 e- nu_ebar. The B_s oscillates |
| | 3452 | into a B_sbar which decays partonically to c cbar s sbar. |
| | 3453 | |
| | 3454 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3455 | 143 PI+ 211 1 107 9 0 0 1.90 -0.02 24.27 24.35 0.14 |
| | 3456 | 144 PI- -211 1 107 9 0 0 0.32 0.00 6.77 6.78 0.14 |
| | 3457 | 145 PI0 111 1 107 9 0 0 0.11 -0.02 3.07 3.08 0.14 |
| | 3458 | 146 PI+ 211 1 108 9 0 0 1.80 0.19 29.01 29.07 0.14 |
| | 3459 | 147 PI0 111 1 108 9 0 0 0.27 -0.25 6.57 6.58 0.14 |
| | 3460 | ....... |
| | 3461 | 163 RHO0 113 198 123 43 194 195 -18.44 -9.34 6.79 21.77 0.77 |
| | 3462 | 164 E- 11 1 123 43 0 0 -6.49 -5.26 5.27 9.88 0.00 |
| | 3463 | 165 NU_EBAR -12 1 123 43 0 0 -0.50 -0.38 -0.09 0.63 0.00 |
| | 3464 | ....... |
| | 3465 | 176 B_SBAR0 -531 199 136 32 207 208 14.56 -33.17 -4.60 36.91 5.38 |
| | 3466 | 205 PI0 111 1 187 9 0 0 0.51 -0.06 1.56 1.65 0.14 |
| | 3467 | 206 PI0 111 1 187 9 0 0 0.14 0.12 1.63 1.64 0.14 |
| | 3468 | |
| | 3469 | ---HEAVY FLAVOUR DECAYS--- |
| | 3470 | |
| | 3471 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3472 | 207 BQRK 5 155 176 208 209 211 13.20 -30.08 -4.17 33.47 4.88 |
| | 3473 | 208 SBAR -3 125 176 211 212 211 1.35 -3.09 -0.43 3.43 0.50 |
| | 3474 | 209 CQRK 4 123 207 210 213 210 2.30 -5.94 -0.61 6.59 1.55 |
| | 3475 | 210 CBAR -4 124 207 209 215 209 3.58 -8.37 -1.74 9.40 1.55 |
| | 3476 | 211 SQRK 3 124 207 207 217 207 7.33 -15.77 -1.82 17.49 0.50 |
| | 3477 | 212 SBAR -3 160 208 221 223 221 1.35 -3.09 -0.43 3.43 0.50 |
| | 3478 | |
| | 3479 | The B_sbar decay products hadronize to eta_c K+ K-: |
| | 3480 | |
| | 3481 | ---CLUSTER DECAYS--- |
| | 3482 | |
| | 3483 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3484 | 224 ETA_C 441 199 222 213 227 229 4.87 -12.18 -2.12 13.62 2.98 |
| | 3485 | 225 K- -321 1 223 217 0 0 8.22 -17.67 -2.03 19.60 0.49 |
| | 3486 | 226 K+ 321 1 223 217 0 0 1.47 -3.31 -0.45 3.69 0.49 |
| | 3487 | |
| | 3488 | The eta_c decays partonically to 3 gluons: |
| | 3489 | |
| | 3490 | ---HEAVY FLAVOUR DECAYS--- |
| | 3491 | |
| | 3492 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3493 | 227 GLUON 21 123 224 229 230 228 2.59 -4.45 -1.11 5.32 0.75 |
| | 3494 | 228 GLUON 21 124 224 227 232 229 0.84 -4.20 -0.51 4.38 0.75 |
| | 3495 | 229 GLUON 21 124 224 228 234 227 1.44 -3.53 -0.50 3.92 0.75 |
| | 3496 | |
| | 3497 | Finally the 3 gluons hadronize to pi+ pi- 4 pi0: |
| | 3498 | |
| | 3499 | ---CLUSTER DECAYS--- |
| | 3500 | |
| | 3501 | IHEP ID IDPDG IST MO1 MO2 DA1 DA2 P-X P-Y P-Z ENERGY MASS |
| | 3502 | 245 PI- -211 1 242 230 0 0 1.53 -3.79 -0.46 4.11 0.14 |
| | 3503 | 246 PI0 111 1 242 230 0 0 0.06 -0.12 -0.07 0.20 0.14 |
| | 3504 | 247 PI0 111 1 243 232 0 0 0.52 -0.39 0.03 0.66 0.14 |
| | 3505 | 248 PI0 111 1 243 232 0 0 1.30 -3.27 -1.01 3.66 0.14 |
| | 3506 | 249 PI0 111 1 244 234 0 0 1.02 -3.98 -0.74 4.18 0.14 |
| | 3507 | 250 PI+ 211 1 244 234 0 0 0.43 -0.64 0.14 0.80 0.14 |
| | 3508 | |
| | 3509 | After the 1000 events requested have been generated, an analysis of |
| | 3510 | the associated weight distribution and cross section is printed. |
git://git.uio.no / u / mrichter / AliRoot.git / blame_incremental