3 <title>Timelike Showers</title>
4 <link rel="stylesheet" type="text/css" href="pythia.css"/>
5 <link rel="shortcut icon" href="pythia32.gif"/>
9 <script language=javascript type=text/javascript>
10 function stopRKey(evt) {
11 var evt = (evt) ? evt : ((event) ? event : null);
12 var node = (evt.target) ? evt.target :((evt.srcElement) ? evt.srcElement : null);
13 if ((evt.keyCode == 13) && (node.type=="text"))
17 document.onkeypress = stopRKey;
20 if($_POST['saved'] == 1) {
21 if($_POST['filepath'] != "files/") {
22 echo "<font color='red'>SETTINGS SAVED TO FILE</font><br/><br/>"; }
24 echo "<font color='red'>NO FILE SELECTED YET.. PLEASE DO SO </font><a href='SaveSettings.php'>HERE</a><br/><br/>"; }
28 <form method='post' action='TimelikeShowers.php'>
30 <h2>Timelike Showers</h2>
32 The PYTHIA algorithm for timelike final-state showers is based on
33 the article [<a href="Bibliography.php" target="page">Sjo05</a>], where a transverse-momentum-ordered
34 evolution scheme is introduced, with the extension to fully interleaved
35 evolution covered in [<a href="Bibliography.php" target="page">Cor10a</a>]. This algorithm is influenced by
36 the previous mass-ordered algorithm in PYTHIA [<a href="Bibliography.php" target="page">Ben87</a>] and by
37 the dipole-emission formulation in Ariadne [<a href="Bibliography.php" target="page">Gus86</a>]. From the
38 mass-ordered algorithm it inherits a merging procedure for first-order
39 gluon-emission matrix elements in essentially all two-body decays
40 in the standard model and its minimal supersymmetric extension
41 [<a href="Bibliography.php" target="page">Nor01</a>].
44 The normal user is not expected to call <code>TimeShower</code> directly,
45 but only have it called from <code>Pythia</code>. Some of the parameters
46 below, in particular <code>TimeShower:alphaSvalue</code>, would be of
47 interest for a tuning exercise, however.
49 <h3>Main variables</h3>
51 Often the maximum scale of the FSR shower evolution is understood from the
52 context. For instance, in a resonace decay half the resonance mass sets an
53 absolute upper limit. For a hard process in a hadronic collision the choice
54 is not as unique. Here the <?php $filepath = $_GET["filepath"];
55 echo "<a href='CouplingsAndScales.php?filepath=".$filepath."' target='page'>";?>factorization
56 scale</a> has been chosen as the maximum evolution scale. This would be
57 the <i>pT</i> for a <i>2 -> 2</i> process, supplemented by mass terms
58 for massive outgoing particles. For some special applications we do allow
61 <br/><br/><table><tr><td><strong>TimeShower:pTmaxMatch </td><td> (<code>default = <strong>1</strong></code>; <code>minimum = 0</code>; <code>maximum = 2</code>)</td></tr></table>
62 Way in which the maximum shower evolution scale is set to match the
63 scale of the hard process itself.
65 <input type="radio" name="1" value="0"><strong>0 </strong>: <b>(i)</b> if the final state of the hard process (not counting subsequent resonance decays) contains at least one quark (<ei>u, d, s, c ,b</ei>), gluon or photon then <ei>pT_max</ei> is chosen to be the factorization scale for internal processes and the <code>scale</code> value for Les Houches input; <b>(ii)</b> if not, emissions are allowed to go all the way up to the kinematical limit (i.e. to half the dipole mass). This option agrees with the corresponding one for <aloc href="SpacelikeShowers">spacelike showers</aloc>. There the reasoning is that in the former set of processes the ISR emission of yet another quark, gluon or photon could lead to doublecounting, while no such danger exists in the latter case. The argument is less compelling for timelike showers, but could be a reasonable starting point. <br/>
66 <input type="radio" name="1" value="1" checked="checked"><strong>1 </strong>: always use the factorization scale for an internal process and the <code>scale</code> value for Les Houches input, i.e. the lower value. This should avoid doublecounting, but may leave out some emissions that ought to have been simulated. (Also known as wimpy showers.) <br/>
67 <input type="radio" name="1" value="2"><strong>2 </strong>: always allow emissions up to the kinematical limit (i.e. to half the dipole mass). This will simulate all possible event topologies, but may lead to doublecounting. (Also known as power showers.) <br/>
68 <br/><b>Note:</b> These options only apply to the hard interaction.
69 Emissions off subsequent multiple interactions are always constrainted
70 to be below the factorization scale of the process itself. They also
71 assume you use interleaved evolution, so that FSR is in direct
72 competition with ISR for the hardest emission. If you already
73 generated a number of ISR partons at low <ei>pT</ei>, it would not
74 make sense to have a later FSR shower up to the kinematical for all
77 <br/><br/><table><tr><td><strong>TimeShower:pTmaxFudge </td><td></td><td> <input type="text" name="2" value="1.0" size="20"/> (<code>default = <strong>1.0</strong></code>; <code>minimum = 0.25</code>; <code>maximum = 2.0</code>)</td></tr></table>
78 In cases where the above <code>pTmaxMatch</code> rules would imply
79 that <i>pT_max = pT_factorization</i>, <code>pTmaxFudge</code>
80 introduces a multiplicative factor <i>f</i> such that instead
81 <i>pT_max = f * pT_factorization</i>. Only applies to the hardest
82 interaction in an event, cf. below. It is strongly suggested that
83 <i>f = 1</i>, but variations around this default can be useful to
85 <br/><b>Note:</b>Scales for resonance decays are not affected, but can
86 be set separately by <?php $filepath = $_GET["filepath"];
87 echo "<a href='UserHooks.php?filepath=".$filepath."' target='page'>";?>user hooks</a>.
90 <br/><br/><table><tr><td><strong>TimeShower:pTmaxFudgeMI </td><td></td><td> <input type="text" name="3" value="1.0" size="20"/> (<code>default = <strong>1.0</strong></code>; <code>minimum = 0.25</code>; <code>maximum = 2.0</code>)</td></tr></table>
91 A multiplicative factor <i>f</i> such that
92 <i>pT_max = f * pT_factorization</i>, as above, but here for the
93 non-hardest interactions (when multiple interactions are allowed).
96 <br/><br/><table><tr><td><strong>TimeShower:pTdampMatch </td><td> (<code>default = <strong>0</strong></code>; <code>minimum = 0</code>; <code>maximum = 2</code>)</td></tr></table>
97 These options only take effect when a process is allowed to radiate up
98 to the kinematical limit by the above <code>pTmaxMatch</code> choice,
99 and no matrix-element corrections are available. Then, in many processes,
100 the fall-off in <ei>pT</ei> will be too slow by one factor of <ei>pT^2</ei>.
101 That is, while showers have an approximate <ei>dpT^2/pT^2</ei> shape, often
102 it should become more like <ei>dpT^2/pT^4</ei> at <ei>pT</ei> values above
103 the scale of the hard process. This argument is more obvious for ISR,
104 but is taken over unchanged for FSR to have a symmetric description.
106 <input type="radio" name="4" value="0" checked="checked"><strong>0 </strong>: emissions go up to the kinematical limit, with no special dampening. <br/>
107 <input type="radio" name="4" value="1"><strong>1 </strong>: emissions go up to the kinematical limit, but dampened by a factor <ei>k^2 Q^2_fac/(pT^2 + k^2 Q^2_fac)</ei>, where <ei>Q_fac</ei> is the factorization scale and <ei>k</ei> is a multiplicative fudge factor stored in <code>pTdampFudge</code> below. <br/>
108 <input type="radio" name="4" value="2"><strong>2 </strong>: emissions go up to the kinematical limit, but dampened by a factor <ei>k^2 Q^2_ren/(pT^2 + k^2 Q^2_ren)</ei>, where <ei>Q_ren</ei> is the renormalization scale and <ei>k</ei> is a multiplicative fudge factor stored in <code>pTdampFudge</code> below. <br/>
109 <br/><b>Note:</b> These options only apply to the hard interaction.
110 Emissions off subsequent multiple interactions are always constrainted
111 to be below the factorization scale of the process itself.
113 <br/><br/><table><tr><td><strong>TimeShower:pTdampFudge </td><td></td><td> <input type="text" name="5" value="1.0" size="20"/> (<code>default = <strong>1.0</strong></code>; <code>minimum = 0.25</code>; <code>maximum = 4.0</code>)</td></tr></table>
114 In cases 1 and 2 above, where a dampening is imposed at around the
115 factorization or renormalization scale, respectively, this allows the
116 <i>pT</i> scale of dampening of radiation by a half to be shifted
117 by this factor relative to the default <i>Q_fac</i> or <i>Q_ren</i>.
118 This number ought to be in the neighbourhood of unity, but variations
119 away from this value could do better in some processes.
123 The amount of QCD radiation in the shower is determined by
124 <br/><br/><table><tr><td><strong>TimeShower:alphaSvalue </td><td></td><td> <input type="text" name="6" value="0.1383" size="20"/> (<code>default = <strong>0.1383</strong></code>; <code>minimum = 0.06</code>; <code>maximum = 0.25</code>)</td></tr></table>
125 The <i>alpha_strong</i> value at scale <i>M_Z^2</i>. The default
126 value corresponds to a crude tuning to LEP data, to be improved.
130 The actual value is then regulated by the running to the scale
131 <i>pT^2</i>, at which the shower evaluates <i>alpha_strong</i>
133 <br/><br/><table><tr><td><strong>TimeShower:alphaSorder </td><td> (<code>default = <strong>1</strong></code>; <code>minimum = 0</code>; <code>maximum = 2</code>)</td></tr></table>
134 Order at which <ei>alpha_strong</ei> runs,
136 <input type="radio" name="7" value="0"><strong>0 </strong>: zeroth order, i.e. <ei>alpha_strong</ei> is kept fixed.<br/>
137 <input type="radio" name="7" value="1" checked="checked"><strong>1 </strong>: first order, which is the normal value.<br/>
138 <input type="radio" name="7" value="2"><strong>2 </strong>: second order. Since other parts of the code do not go to second order there is no strong reason to use this option, but there is also nothing wrong with it.<br/>
141 QED radiation is regulated by the <i>alpha_electromagnetic</i>
142 value at the <i>pT^2</i> scale of a branching.
144 <br/><br/><table><tr><td><strong>TimeShower:alphaEMorder </td><td> (<code>default = <strong>1</strong></code>; <code>minimum = -1</code>; <code>maximum = 1</code>)</td></tr></table>
145 The running of <ei>alpha_em</ei>.
147 <input type="radio" name="8" value="1" checked="checked"><strong>1 </strong>: first-order running, constrained to agree with <code>StandardModel:alphaEMmZ</code> at the <ei>Z^0</ei> mass. <br/>
148 <input type="radio" name="8" value="0"><strong>0 </strong>: zeroth order, i.e. <ei>alpha_em</ei> is kept fixed at its value at vanishing momentum transfer.<br/>
149 <input type="radio" name="8" value="-1"><strong>-1 </strong>: zeroth order, i.e. <ei>alpha_em</ei> is kept fixed, but at <code>StandardModel:alphaEMmZ</code>, i.e. its value at the <ei>Z^0</ei> mass. <br/>
152 The rate of radiation if divergent in the <i>pT -> 0</i> limit. Here,
153 however, perturbation theory is expected to break down. Therefore an
154 effective <i>pT_min</i> cutoff parameter is introduced, below which
155 no emissions are allowed. The cutoff may be different for QCD and QED
156 radiation off quarks, and is mainly a technical parameter for QED
157 radiation off leptons.
159 <br/><br/><table><tr><td><strong>TimeShower:pTmin </td><td></td><td> <input type="text" name="9" value="0.4" size="20"/> (<code>default = <strong>0.4</strong></code>; <code>minimum = 0.1</code>; <code>maximum = 2.0</code>)</td></tr></table>
160 Parton shower cut-off <i>pT</i> for QCD emissions.
163 <br/><br/><table><tr><td><strong>TimeShower:pTminChgQ </td><td></td><td> <input type="text" name="10" value="0.4" size="20"/> (<code>default = <strong>0.4</strong></code>; <code>minimum = 0.1</code>; <code>maximum = 2.0</code>)</td></tr></table>
164 Parton shower cut-off <i>pT</i> for photon coupling to coloured particle.
167 <br/><br/><table><tr><td><strong>TimeShower:pTminChgL </td><td></td><td> <input type="text" name="11" value="0.0005" size="20"/> (<code>default = <strong>0.0005</strong></code>; <code>minimum = 0.0001</code>; <code>maximum = 2.0</code>)</td></tr></table>
168 Parton shower cut-off <i>pT</i> for pure QED branchings.
169 Assumed smaller than (or equal to) <code>pTminChgQ</code>.
173 Shower branchings <i>gamma -> f fbar</i>, where <i>f</i> is a
174 quark or lepton, in part compete with the hard processes involving
175 <i>gamma^*/Z^0</i> production. In order to avoid overlap it makes
176 sense to correlate the maximum <i>gamma</i> mass allowed in showers
177 with the minumum <i>gamma^*/Z^0</i> mass allowed in hard processes.
178 In addition, the shower contribution only contains the pure
179 <i>gamma^*</i> contribution, i.e. not the <i>Z^0</i> part, so
180 the mass spectrum above 50 GeV or so would not be well described.
182 <br/><br/><table><tr><td><strong>TimeShower:mMaxGamma </td><td></td><td> <input type="text" name="12" value="10.0" size="20"/> (<code>default = <strong>10.0</strong></code>; <code>minimum = 0.001</code>; <code>maximum = 50.0</code>)</td></tr></table>
183 Maximum invariant mass allowed for the created fermion pair in a
184 <i>gamma -> f fbar</i> branching in the shower.
187 <h3>Interleaved evolution</h3>
189 Multiple interactions (MI) and initial-state showers (ISR) are
190 always interleaved, as follows. Starting from the hard interaction,
191 the complete event is constructed by a set of steps. In each step
192 the <i>pT</i> scale of the previous step is used as starting scale
193 for a downwards evolution. The MI and ISR components each make
194 their respective Monte Carlo choices for the next lower <i>pT</i>
195 value. The one with larger <i>pT</i> is allowed to carry out its
196 proposed action, thereby modifying the conditions for the next steps.
197 This is relevant since the two components compete for the energy
198 contained in the beam remnants: both an interaction and an emission
199 take avay some of the energy, leaving less for the future. The end
200 result is a combined chain of decreasing <i>pT</i> values, where
201 ones associated with new interactions and ones with new emissions
205 There is no corresponding requirement for final-state radiation (FSR)
206 to be interleaved. Such an FSR emission does not compete directly for
207 beam energy (but see below), and also can be viewed as occuring after
208 the other two components in some kind of time sense. Interleaving is
209 allowed, however, since it can be argued that a high-<i>pT</i> FSR
210 occurs on shorter time scales than a low-<i>pT</i> MI, say.
211 Backwards evolution of ISR is also an example that physical time
212 is not the only possible ordering principle, but that one can work
213 with conditional probabilities: given the partonic picture at a
214 specific <i>pT</i> resolution scale, what possibilities are open
215 for a modified picture at a slightly lower <i>pT</i> scale, either
216 by MI, ISR or FSR? Complete interleaving of the three components also
217 offers advantages if one aims at matching to higher-order matrix
218 elements above some given scale.
220 <br/><br/><strong>TimeShower:interleave</strong> <input type="radio" name="13" value="on" checked="checked"><strong>On</strong>
221 <input type="radio" name="13" value="off"><strong>Off</strong>
222 (<code>default = <strong>on</strong></code>)<br/>
223 If on, final-state emissions are interleaved in the same
224 decreasing-<i>pT</i> chain as multiple interactions and initial-state
225 emissions. If off, final-state emissions are only addressed after the
226 multiple interactions and initial-state radiation have been considered.
230 As an aside, it should be noted that such interleaving does not affect
231 showering in resonance decays, such as a <i>Z^0</i>. These decays are
232 only introduced after the production process has been considered in full,
233 and the subsequent FSR is carried out inside the resonance, with
234 preserved resonance mass.
237 One aspect of FSR for a hard process in hadron collisions is that often
238 colour diples are formed between a scattered parton and a beam remnant,
239 or rather the hole left behind by an incoming partons. If such holes
240 are allowed as dipole ends and take the recoil when the scattered parton
241 undergoes a branching then this translates into the need to take some
242 amount of remnant energy also in the case of FSR, i.e. the roles of
243 ISR and FSR are not completely decoupled. The energy taken away is
244 bokkept by increasing the <i>x</i> value assigned to the incoming
245 scattering parton, and a reweighting factor
246 <i>x_new f(x_new, pT^2) / x_old f(x_old, pT^2)</i>
247 in the emission probability ensures that not unphysically large
248 <i>x_new</i> values are reached. Usually such <i>x</i> changes are
249 small, and they can be viewed as a higher-order effect beyond the
250 accuracy of the leading-log initial-state showers.
253 This choice is not unique, however. As an alternative, if nothing else
254 useful for cross-checks, one could imagine that the FSR is completely
255 decoupled from the ISR and beam remnants.
257 <br/><br/><strong>TimeShower:allowBeamRecoil</strong> <input type="radio" name="14" value="on" checked="checked"><strong>On</strong>
258 <input type="radio" name="14" value="off"><strong>Off</strong>
259 (<code>default = <strong>on</strong></code>)<br/>
260 If on, the final-state shower is allowed to borrow energy from
261 the beam remnants as described above, thereby changing the mass of the
262 scattering subsystem. If off, the partons in the scattering subsystem
263 are constrained to borrow energy from each other, such that the total
264 four-momentum of the system is preserved. This flag has no effect
265 on resonance decays, where the shower always preserves the resonance
266 mass, cf. the comment above about showers for resonances never being
270 <br/><br/><strong>TimeShower:dampenBeamRecoil</strong> <input type="radio" name="15" value="on" checked="checked"><strong>On</strong>
271 <input type="radio" name="15" value="off"><strong>Off</strong>
272 (<code>default = <strong>on</strong></code>)<br/>
273 When beam recoil is allowed there is still some ambiguity how far
274 into the beam end of the dipole that emission should be allowed.
275 It is dampened in the beam region, but probably not enough.
276 When on an additional suppression factor
277 <i>4 pT2_hard / (4 pT2_hard + m2)</i> is multiplied on to the
278 emission probability. Here <i>pT_hard</i> is the transverse momentum
279 of the radiating parton and <i>m</i> the off-shell mass it acquires
280 by the branching, <i>m2 = pT2/(z(1-z))</i>. Note that
281 <i>m2 = 4 pT2_hard</i> is the kinematical limit for a scattering
282 at 90 degrees without beam recoil.
285 <h3>Radiation off octet onium states</h3>
287 In the current implementation, charmonium and bottomonium production
288 can proceed either through colour singlet or colour octet mechanisms,
289 both of them implemented in terms of <i>2 -> 2</i> hard processes
290 such as <i>g g -> (onium) g</i>.
291 In the former case the state does not radiate and the onium therefore
292 is produced in isolation, up to normal underlying-event activity. In
293 the latter case the situation is not so clear, but it is sensible to
294 assume that a shower can evolve. (Assuming, of course, that the
295 transverse momentum of the onium state is sufficiently high that
296 radiation is of relevance.)
299 There could be two parts to such a shower. Firstly a gluon (or even a
300 quark, though less likely) produced in a hard <i>2 -> 2</i> process
301 can undergo showering into many gluons, whereof one branches into the
302 heavy-quark pair. Secondly, once the pair has been produced, each quark
303 can radiate further gluons. This latter kind of emission could easily
304 break up a semibound quark pair, but might also create a new semibound
305 state where before an unbound pair existed, and to some approximation
306 these two effects should balance in the onium production rate.
307 The showering "off an onium state" as implemented here therefore should
308 not be viewed as an accurate description of the emission history
309 step by step, but rather as an effective approach to ensure that the
310 octet onium produced "in the hard process" is embedded in a realistic
311 amount of jet activity.
312 Of course both the isolated singlet and embedded octet are likely to
313 be extremes, but hopefully the mix of the two will strike a reasonable
314 balance. However, it is possible that some part of the octet production
315 occurs in channels where it should not be accompanied by (hard) radiation.
316 Therefore reducing the fraction of octet onium states allowed to radiate
317 is a valid variation to explore uncertainties.
320 If an octet onium state is chosen to radiate, the simulation of branchings
321 is based on the assumption that the full radiation is provided by an
322 incoherent sum of radiation off the quark and off the antiquark of the
323 onium state. Thus the splitting kernel is taken to be the normal
324 <i>q -> q g</i> one, multiplied by a factor of two. Obviously this is
325 a simplification of a more complex picture, averaging over factors pulling
326 in different directions. Firstly, radiation off a gluon ought
327 to be enhanced by a factor 9/4 relative to a quark rather than the 2
328 now used, but this is a minor difference. Secondly, our use of the
329 <i>q -> q g</i> branching kernel is roughly equivalent to always
330 following the harder gluon in a <i>g -> g g</i> branching. This could
331 give us a bias towards producing too hard onia. A soft gluon would have
332 little phase space to branch into a heavy-quark pair however, so the
333 bias may not be as big as it would seem at first glance. Thirdly,
334 once the gluon has branched into a quark pair, each quark carries roughly
335 only half of the onium energy. The maximum energy per emitted gluon should
336 then be roughly half the onium energy rather than the full, as it is now.
337 Thereby the energy of radiated gluons is exaggerated, i.e. onia become too
338 soft. So the second and the third points tend to cancel each other.
341 Finally, note that the lower cutoff scale of the shower evolution depends
342 on the onium mass rather than on the quark mass, as it should be. Gluons
343 below the octet-onium scale should only be part of the octet-to-singlet
346 <br/><br/><table><tr><td><strong>TimeShower:octetOniumFraction </td><td></td><td> <input type="text" name="16" value="1." size="20"/> (<code>default = <strong>1.</strong></code>; <code>minimum = 0.</code>; <code>maximum = 1.</code>)</td></tr></table>
347 Allow colour-octet charmonium and bottomonium states to radiate gluons.
348 0 means that no octet-onium states radiate, 1 that all do, with possibility
349 to interpolate between these two extremes.
352 <br/><br/><table><tr><td><strong>TimeShower:octetOniumColFac </td><td></td><td> <input type="text" name="17" value="2." size="20"/> (<code>default = <strong>2.</strong></code>; <code>minimum = 0.</code>; <code>maximum = 4.</code>)</td></tr></table>
353 The colour factor used used in the splitting kernel for those octet onium
354 states that are allowed to radiate, normalized to the <i>q -> q g</i>
355 splitting kernel. Thus the default corresponds to twice the radiation
356 off a quark. The physically preferred range would be between 1 and 9/4.
359 <h3>Further variables</h3>
361 There are several possibilities you can use to switch on or off selected
362 branching types in the shower, or in other respects simplify the shower.
363 These should normally not be touched. Their main function is for
366 <br/><br/><strong>TimeShower:QCDshower</strong> <input type="radio" name="18" value="on" checked="checked"><strong>On</strong>
367 <input type="radio" name="18" value="off"><strong>Off</strong>
368 (<code>default = <strong>on</strong></code>)<br/>
369 Allow a QCD shower, i.e. branchings <i>q -> q g</i>, <i>g -> g g</i>
370 and <i>g -> q qbar</i>; on/off = true/false.
373 <br/><br/><table><tr><td><strong>TimeShower:nGluonToQuark </td><td></td><td> <input type="text" name="19" value="5" size="20"/> (<code>default = <strong>5</strong></code>; <code>minimum = 0</code>; <code>maximum = 5</code>)</td></tr></table>
374 Number of allowed quark flavours in <i>g -> q qbar</i> branchings
375 (phase space permitting). A change to 4 would exclude
376 <i>g -> b bbar</i>, etc.
379 <br/><br/><strong>TimeShower:QEDshowerByQ</strong> <input type="radio" name="20" value="on" checked="checked"><strong>On</strong>
380 <input type="radio" name="20" value="off"><strong>Off</strong>
381 (<code>default = <strong>on</strong></code>)<br/>
382 Allow quarks to radiate photons, i.e. branchings <i>q -> q gamma</i>;
386 <br/><br/><strong>TimeShower:QEDshowerByL</strong> <input type="radio" name="21" value="on" checked="checked"><strong>On</strong>
387 <input type="radio" name="21" value="off"><strong>Off</strong>
388 (<code>default = <strong>on</strong></code>)<br/>
389 Allow leptons to radiate photons, i.e. branchings <i>l -> l gamma</i>;
393 <br/><br/><strong>TimeShower:QEDshowerByGamma</strong> <input type="radio" name="22" value="on" checked="checked"><strong>On</strong>
394 <input type="radio" name="22" value="off"><strong>Off</strong>
395 (<code>default = <strong>on</strong></code>)<br/>
396 Allow photons to branch into lepton or quark pairs, i.e. branchings
397 <i>gamma -> l+ l-</i> and <i>gamma -> q qbar</i>;
401 <br/><br/><table><tr><td><strong>TimeShower:nGammaToQuark </td><td></td><td> <input type="text" name="23" value="5" size="20"/> (<code>default = <strong>5</strong></code>; <code>minimum = 0</code>; <code>maximum = 5</code>)</td></tr></table>
402 Number of allowed quark flavours in <i>gamma -> q qbar</i> branchings
403 (phase space permitting). A change to 4 would exclude
404 <i>g -> b bbar</i>, etc.
407 <br/><br/><table><tr><td><strong>TimeShower:nGammaToLepton </td><td></td><td> <input type="text" name="24" value="3" size="20"/> (<code>default = <strong>3</strong></code>; <code>minimum = 0</code>; <code>maximum = 3</code>)</td></tr></table>
408 Number of allowed lepton flavours in <i>gamma -> l+ l-</i> branchings
409 (phase space permitting). A change to 2 would exclude
410 <i>gamma -> tau+ tau-</i>, and a change to 1 also
411 <i>gamma -> mu+ mu-</i>.
414 <br/><br/><strong>TimeShower:MEcorrections</strong> <input type="radio" name="25" value="on" checked="checked"><strong>On</strong>
415 <input type="radio" name="25" value="off"><strong>Off</strong>
416 (<code>default = <strong>on</strong></code>)<br/>
417 Use of matrix element corrections where available; on/off = true/false.
420 <br/><br/><strong>TimeShower:phiPolAsym</strong> <input type="radio" name="26" value="on" checked="checked"><strong>On</strong>
421 <input type="radio" name="26" value="off"><strong>Off</strong>
422 (<code>default = <strong>on</strong></code>)<br/>
423 Azimuthal asymmetry induced by gluon polarization; on/off = true/false.
426 <input type="hidden" name="saved" value="1"/>
429 echo "<input type='hidden' name='filepath' value='".$_GET["filepath"]."'/>"?>
431 <table width="100%"><tr><td align="right"><input type="submit" value="Save Settings" /></td></tr></table>
436 if($_POST["saved"] == 1)
438 $filepath = $_POST["filepath"];
439 $handle = fopen($filepath, 'a');
441 if($_POST["1"] != "1")
443 $data = "TimeShower:pTmaxMatch = ".$_POST["1"]."\n";
444 fwrite($handle,$data);
446 if($_POST["2"] != "1.0")
448 $data = "TimeShower:pTmaxFudge = ".$_POST["2"]."\n";
449 fwrite($handle,$data);
451 if($_POST["3"] != "1.0")
453 $data = "TimeShower:pTmaxFudgeMI = ".$_POST["3"]."\n";
454 fwrite($handle,$data);
456 if($_POST["4"] != "0")
458 $data = "TimeShower:pTdampMatch = ".$_POST["4"]."\n";
459 fwrite($handle,$data);
461 if($_POST["5"] != "1.0")
463 $data = "TimeShower:pTdampFudge = ".$_POST["5"]."\n";
464 fwrite($handle,$data);
466 if($_POST["6"] != "0.1383")
468 $data = "TimeShower:alphaSvalue = ".$_POST["6"]."\n";
469 fwrite($handle,$data);
471 if($_POST["7"] != "1")
473 $data = "TimeShower:alphaSorder = ".$_POST["7"]."\n";
474 fwrite($handle,$data);
476 if($_POST["8"] != "1")
478 $data = "TimeShower:alphaEMorder = ".$_POST["8"]."\n";
479 fwrite($handle,$data);
481 if($_POST["9"] != "0.4")
483 $data = "TimeShower:pTmin = ".$_POST["9"]."\n";
484 fwrite($handle,$data);
486 if($_POST["10"] != "0.4")
488 $data = "TimeShower:pTminChgQ = ".$_POST["10"]."\n";
489 fwrite($handle,$data);
491 if($_POST["11"] != "0.0005")
493 $data = "TimeShower:pTminChgL = ".$_POST["11"]."\n";
494 fwrite($handle,$data);
496 if($_POST["12"] != "10.0")
498 $data = "TimeShower:mMaxGamma = ".$_POST["12"]."\n";
499 fwrite($handle,$data);
501 if($_POST["13"] != "on")
503 $data = "TimeShower:interleave = ".$_POST["13"]."\n";
504 fwrite($handle,$data);
506 if($_POST["14"] != "on")
508 $data = "TimeShower:allowBeamRecoil = ".$_POST["14"]."\n";
509 fwrite($handle,$data);
511 if($_POST["15"] != "on")
513 $data = "TimeShower:dampenBeamRecoil = ".$_POST["15"]."\n";
514 fwrite($handle,$data);
516 if($_POST["16"] != "1.")
518 $data = "TimeShower:octetOniumFraction = ".$_POST["16"]."\n";
519 fwrite($handle,$data);
521 if($_POST["17"] != "2.")
523 $data = "TimeShower:octetOniumColFac = ".$_POST["17"]."\n";
524 fwrite($handle,$data);
526 if($_POST["18"] != "on")
528 $data = "TimeShower:QCDshower = ".$_POST["18"]."\n";
529 fwrite($handle,$data);
531 if($_POST["19"] != "5")
533 $data = "TimeShower:nGluonToQuark = ".$_POST["19"]."\n";
534 fwrite($handle,$data);
536 if($_POST["20"] != "on")
538 $data = "TimeShower:QEDshowerByQ = ".$_POST["20"]."\n";
539 fwrite($handle,$data);
541 if($_POST["21"] != "on")
543 $data = "TimeShower:QEDshowerByL = ".$_POST["21"]."\n";
544 fwrite($handle,$data);
546 if($_POST["22"] != "on")
548 $data = "TimeShower:QEDshowerByGamma = ".$_POST["22"]."\n";
549 fwrite($handle,$data);
551 if($_POST["23"] != "5")
553 $data = "TimeShower:nGammaToQuark = ".$_POST["23"]."\n";
554 fwrite($handle,$data);
556 if($_POST["24"] != "3")
558 $data = "TimeShower:nGammaToLepton = ".$_POST["24"]."\n";
559 fwrite($handle,$data);
561 if($_POST["25"] != "on")
563 $data = "TimeShower:MEcorrections = ".$_POST["25"]."\n";
564 fwrite($handle,$data);
566 if($_POST["26"] != "on")
568 $data = "TimeShower:phiPolAsym = ".$_POST["26"]."\n";
569 fwrite($handle,$data);
578 <!-- Copyright (C) 2010 Torbjorn Sjostrand -->