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0795afa3 | 1 | * |
2 | * $Id$ | |
3 | * | |
4 | * $Log$ | |
5 | * Revision 1.2 1996/12/04 17:39:53 cernlib | |
6 | * Version 7.22 from author | |
7 | * | |
8 | * | |
9 | * This directory was created from /afs/cern.ch/user/m/mclareni/isajet/isajet.car patch isassdoc | |
10 | ISASUSY 7.21 | |
11 | Decay Modes in the Minimal Supersymmetric Model | |
12 | ||
13 | Howard Baer | |
14 | Florida State University | |
15 | Talahassee, FL 32306 | |
16 | ||
17 | Frank E. Paige | |
18 | Brookhaven National Laboratory | |
19 | Upton, NY 11973 | |
20 | ||
21 | S.D. Protopopescu | |
22 | Brookhaven National Laboratory | |
23 | Upton, NY 11973 | |
24 | ||
25 | Xerxes Tata | |
26 | University of Hawaii | |
27 | Honolulu, HI 96822 | |
28 | ||
29 | ||
30 | ||
31 | The code in patch ISASUSY of ISAJET calculates decay modes of | |
32 | supersymmetric particles based on the work of H. Baer, M. Bisset, D. | |
33 | Dzialo (Karatas), X. Tata, J. Woodside, and their collaborators. The | |
34 | calculations assume the minimal supersymmetric extension of the | |
35 | standard model. Supersymmetric grand unification is assumed by | |
36 | default in the chargino and neutralino mass matrices, although the | |
37 | user can override this by specifying arbitrary U(1) and SU(2) gaugino | |
38 | masses at the weak scale. The squark, left and right slepton and | |
39 | sneutrino masses are treated as arbitrary. Soft breaking masses are | |
40 | input for the 3rd generation; mass eigenstates are computed from | |
41 | these. Most calculations are done at the tree level, but one-loop | |
42 | results for gluino loop decays, H -> GM GM and H -> GL GL, loop | |
43 | corrections to the Higgs mass spectrum and couplings, and QCD | |
44 | corrections to H -> q qbar are included. The Higgs masses have been | |
45 | calculated using the effective potential approximation including both | |
46 | top and bottom Yukawa and mixing effects. Mike Bisset and Xerxes Tata | |
47 | have contributed the Higgs mass, couplings, and decay routines. Note | |
48 | that e+e- annihilation to SUSY particles and SUSY Higgs bosons have | |
49 | been included in ISAJET versions >7.11. The following are NOT included | |
50 | in this version: | |
51 | ||
52 | * WH and ZH Higgs production mechanisms in hadronic collisions | |
53 | ||
54 | * Large tan(beta) solution (tan(beta)<=10 should be chosen) | |
55 | ||
56 | * Non-degenerate 1st and 2nd generation sfermions | |
57 | ||
58 | These and other processes may be added in future versions as the physics | |
59 | interest warrants. Note that the details of the masses and the decay | |
60 | modes can be quite sensitive to choices of standard model parameters | |
61 | such as the QCD coupling ALFA3 and the quark masses. To change these, | |
62 | you must modify subroutine SSMSSM. By default, ALFA3=.12. | |
63 | ||
64 | All the mass spectrum and branching ratio calculations in ISASUSY | |
65 | are performed by the call to | |
66 | ||
67 | SUBROUTINE SSMSSM(XM1,XM2,XMG,XMS,XMTL,XMTR,XMLL,XMLR,XMNL | |
68 | $,XTANB,XMHA,XMU,XMT,XAT,XMBR,XAB,IALLOW) | |
69 | ||
70 | where the following are taken to be independent parameters: | |
71 | ||
72 | XM1 = U(1) gaugino mass | |
73 | = computed from XMG if > 1E19 | |
74 | XM2 = SU(2) gaugino mass | |
75 | = computed from XMG if > 1E19 | |
76 | XMG = gluino mass | |
77 | XMS = common u,d,s,c squark mass | |
78 | XMTL = left soft breaking stop mass | |
79 | XMTR = right soft breaking stop mass | |
80 | XMBR = right soft breaking sbottom mass | |
81 | XMLL = left slepton mass | |
82 | XMLR = right slepton mass | |
83 | XMNL = sneutrino mass | |
84 | XTANB = tan(beta) = ratio of vev's | |
85 | = 1/R (of old Baer-Tata notation). | |
86 | XMU = mu = SUSY Higgs mass | |
87 | = -2*m_1 of Baer et al. | |
88 | XMHA = pseudo-scalar Higgs mass | |
89 | XMT = top quark mass | |
90 | XAT = stop squark trilinear term | |
91 | XAB = sbottom squark trilinear term | |
92 | ||
93 | The variable IALLOW is returned: | |
94 | ||
95 | IALLOW = 1 if Z1SS is not LSP, 0 otherwise | |
96 | ||
97 | All variables are of type REAL except IALLOW, which is INTEGER, and all | |
98 | masses are in GeV. The notation is taken to correspond to that of Haber | |
99 | and Kane, although the Tata Lagrangian is used internally. All other | |
100 | standard model parameters are hard wired in this subroutine; they are | |
101 | not obtained from the rest of ISAJET. The theoretically favored range of | |
102 | these parameters is | |
103 | ||
104 | 50 < M(gluino) < 2000 GeV | |
105 | 50 < M(squark) < 2000 GeV | |
106 | 50 < M(slepton) < 2000 GeV | |
107 | -1000 < mu < 1000 GeV | |
108 | 1 < tan(beta) < mt/mb | |
109 | 100 < M(top) < 200 GeV | |
110 | 50 < M(HA) < 1000 GeV | |
111 | M(t_l), M(t_r) < M(squark) | |
112 | M(b_r) ~ M(squark) | |
113 | -1000 < A_t < 1000 GeV | |
114 | -1000 < A_b < 1000 GeV | |
115 | ||
116 | It is assumed that the lightest supersymmetric particle is the lightest | |
117 | neutralino Z1. Some choices of the above parameters may violate this | |
118 | assumption, yielding a light chargino or light stop squark lighter than | |
119 | Z1SS. In such cases SSMSSM does not compute any branching ratios and | |
120 | returns IALLOW = 1. | |
121 | ||
122 | SSMSSM does not check the parameters or resulting masses against | |
123 | existing experimental data. SSTEST provides a minimal test. This routine | |
124 | is called after SSMSSM by ISAJET and ISASUSY and prints suitable warning | |
125 | messages. | |
126 | ||
127 | SSMSSM first calculates the other SUSY masses and mixings and puts | |
128 | them in the common block /SSPAR/: | |
129 | ||
130 | #include "sspar.inc" | |
131 | ||
132 | It then calculates the widths and branching ratios and puts them in the | |
133 | common block /SSMODE/: | |
134 | ||
135 | #include "ssmode.inc" | |
136 | ||
137 | Decay modes for a given particle are not necessarily adjacent in this | |
138 | common block. Note that the branching ratio calculations use the full | |
139 | matrix elements, which in general will give nonuniform distributions in | |
140 | phase space, but this information is not saved in /SSMODE/. In | |
141 | particular, the decays H -> Z + Z* -> Z + f + fbar give no indication | |
142 | that the f + fbar mass is strongly peaked near the upper limit. | |
143 | ||
144 | All IDENT codes are defined by parameter statements in the PATCHY | |
145 | keep sequence SSTYPE: | |
146 | ||
147 | #include "sstype.inc" | |
148 | ||
149 | These are based on standard ISAJET but can be changed to interface with | |
150 | other generators. Since masses except the t mass are hard wired, one | |
151 | should check the kinematics for any decay before using it with possibly | |
152 | different masses. | |
153 | ||
154 | Instead of specifying all the SUSY parameters at the electroweak | |
155 | scale using the MSSMi commands, one can instead use the SUGRA parameter | |
156 | to specify in the minimal supergravity framework the common scalar mass | |
157 | M_0, the common gaugino mass M_(1/2), and the soft trilinear SUSY | |
158 | breaking parameter A_0 at the GUT scale, the ratio tan(beta) of Higgs | |
159 | vacuum expectation values at the electroweak scale, and sign(mu), the | |
160 | sign of the Higgsino mass term. The renormalization group equations are | |
161 | solved iteratively using Runge-Kutta numerical integration, as follows: | |
162 | ||
163 | (1) The RGE's are run from the weak scale M_Z up to the GUT scale, | |
164 | where alpha_1 = alpha_2, taking all thresholds into account. We use | |
165 | two loop RGE equations for the gauge couplings only. | |
166 | ||
167 | (2) The GUT scale boundary conditions are imposed, and the RGE's | |
168 | are run back to M_Z, again taking thresholds into account. | |
169 | ||
170 | (3) The masses of the SUSY particles and the values of the soft | |
171 | breaking parameters B and mu needed for radiative symmetry are | |
172 | computed, e.g. | |
173 | mu**2(M_Z) = (M_H1**2 - M_H2**2 * tan**2(beta)) | |
174 | /(tan**2(beta)-1) - M_Z**2/2 | |
175 | ||
176 | (4) The 1-loop radiative corrections are computed. | |
177 | ||
178 | (5) The process is then interated until stable results are | |
179 | obtained. | |
180 | ||
181 | This is essentially identical to the procedure used by several other | |
182 | groups. Other possible constraints such as b-tau unification and limits | |
183 | on proton decay have not been included. | |
184 | ||
185 | Patch ISASSRUN of ISAJET provides a main program SSRUN and some | |
186 | utility programs to produce human readable output. These utilities must | |
187 | be rewritten if the IDENT codes in /SSTYPE/ are modified. To create the | |
188 | stand-alone version of ISASUSY with SSRUN, run YPATCHY on isajet.pam | |
189 | with the following cradle: | |
190 | ||
191 | \+USE,*ISASUSY. Select all code | |
192 | \+USE,NOCERN. No CERN Library | |
193 | \+USE,IMPNONE. Use IMPLICIT NONE | |
194 | \+EXE. Write everything to ASM | |
195 | \+PAM. Read PAM file | |
196 | \+QUIT. Quit | |
197 | ||
198 | Compile, link, and run the resulting program, and follow the prompts for | |
199 | input. Patch ISASSRUN also contains a main program SUGRUN that reads | |
200 | the SUGRA parameters, solves the renormalization group equations, and | |
201 | calculates the masses and branching ratios. To create the stand-alone | |
202 | version of ISASUGRA, run YPATCHY with the following cradle: | |
203 | ||
204 | \+USE,*ISASUGRA. Select all code | |
205 | \+USE,NOCERN. No CERN Library | |
206 | \+USE,IMPNONE. Use IMPLICIT NONE | |
207 | \+EXE. Write everything to ASM | |
208 | \+PAM. Read PAM file | |
209 | \+QUIT. Quit | |
210 | ||
211 | To produce the documentation, run YPATCHY with the following cradle: | |
212 | ||
213 | \+USE,CDESUSY,ISASSDOC | |
214 | \+EXE | |
215 | \+PAM | |
216 | \+QUIT | |
217 | ||
218 | This documentation is automatically appended to that for ISAJET. | |
219 | ||
220 | ISASUSY is written in ANSI standard Fortran 77 except that | |
221 | IMPLICIT NONE is used if +USE,IMPNONE is selected in the Patchy cradle. | |
222 | All variables are explicitly typed, and variables starting with | |
223 | I,J,K,L,M,N are not necessarily integers. All external names such as | |
224 | the names of subroutines and common blocks start with the letters SS. | |
225 | Most calculations are done in double precision. If +USE,NOCERN is | |
226 | selected in the Patchy cradle, then the Cernlib routines EISRS1 and its | |
227 | auxiliaries to calculate the eigenvalues of a real symmetric matrix and | |
228 | DDILOG to calculate the dilogarithm function are included. Hence it is | |
229 | not necessary to link with Cernlib. | |
230 | ||
231 | The physics assumptions and details of incorporating the Minimal | |
232 | Supersymmetric Model into ISAJET have appeared in a conference | |
233 | proceedings entitled | |
234 | ||
235 | H. Baer, F. Paige, S. Protopopescu and X. Tata, | |
236 | "Simulating Supersymmetry with ISAJET 7.0/ISASUSY 1.0", | |
237 | ||
238 | which has appeared in the proceedings of the workshop on "Physics at | |
239 | Current Accelerators and Supercolliders", ed. J. Hewett, A. White and | |
240 | D. Zeppenfeld, (Argonne National Laboratory, 1993). Detailed | |
241 | references may be found therein. Users wishing to cite an appropriate | |
242 | source may cite the above report. | |
243 | ||
244 | ||
245 |