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29
30<h2>Event Information</h2>
31
32The <code>Info</code> class collects various one-of-a-kind information,
33some relevant for all events and others for the current event.
34An object <code>info</code> is a public member of the <code>Pythia</code>
35class, so if you e.g. have declared <code>Pythia pythia</code>, the
36<code>Info</code> methods can be accessed by
37<code>pythia.info.method()</code>. Most of this is information that
38could also be obtained e.g. from the event record, but is here more
39directly available. It is primarily intended for processes generated
40internally in PYTHIA, but many of the methods would work also for
41events fed in via the Les Houches Accord.
42
43<h3>List information</h3>
44
45<a name="method1"></a>
46<p/><strong>void Info::list() &nbsp;</strong> <br/>
47a listing of most of the information set for the current event.
48 
49
50<h3>The beams</h3>
51
52<a name="method2"></a>
53<p/><strong>int Info::idA() &nbsp;</strong> <br/>
54 
55<strong>int Info::idB() &nbsp;</strong> <br/>
56the identities of the two beam particles.
57 
58
59<a name="method3"></a>
60<p/><strong>double Info::pzA() &nbsp;</strong> <br/>
61 
62<strong>double Info::pzB() &nbsp;</strong> <br/>
63the longitudinal momenta of the two beam particles.
64 
65
66<a name="method4"></a>
67<p/><strong>double Info::eA() &nbsp;</strong> <br/>
68 
69<strong>double Info::eB() &nbsp;</strong> <br/>
70the energies of the two beam particles.
71 
72
73<a name="method5"></a>
74<p/><strong>double Info::mA() &nbsp;</strong> <br/>
75 
76<strong>double Info::mB() &nbsp;</strong> <br/>
77the masses of the two beam particles.
78 
79
80<a name="method6"></a>
81<p/><strong>double Info::eCM() &nbsp;</strong> <br/>
82 
83<strong>double Info::s() &nbsp;</strong> <br/>
84the CM energy and its square for the two beams.
85 
86
87<h3>Initialization</h3>
88
89<a name="method7"></a>
90<p/><strong>bool Info::tooLowPTmin() &nbsp;</strong> <br/>
91normally false, but true if the proposed <i>pTmin</i> scale was too low
92in timelike or spacelike showers, or in multiparton interactions. In the
93former case the <i>pTmin</i> is raised to some minimal value, in the
94latter the initialization fails (it is impossible to obtain a minijet
95cross section bigger than the nondiffractive one by reducing
96<i>pTmin</i>).
97 
98
99<h3>The event type</h3>
100
101<a name="method8"></a>
102<p/><strong>string Info::name() &nbsp;</strong> <br/>
103 
104<strong>int Info::code() &nbsp;</strong> <br/>
105the name and code of the process that occured.
106 
107
108<a name="method9"></a>
109<p/><strong>int Info::nFinal() &nbsp;</strong> <br/>
110the number of final-state partons in the hard process.
111 
112
113<a name="method10"></a>
114<p/><strong>bool Info::isResolved() &nbsp;</strong> <br/>
115are beam particles resolved, i.e. were PDF's used for the process?
116 
117
118<a name="method11"></a>
119<p/><strong>bool Info::isDiffractiveA() &nbsp;</strong> <br/>
120 
121<strong>bool Info::isDiffractiveB() &nbsp;</strong> <br/>
122is either beam diffractively excited?
123 
124
125<a name="method12"></a>
126<p/><strong>bool Info::isDiffractiveC() &nbsp;</strong> <br/>
127is there central diffraction (a.k.a. double Pomeron exchange)?
128 
129
130<a name="method13"></a>
131<p/><strong>bool Info::isMinBias() &nbsp;</strong> <br/>
132is the process a minimum-bias one?
133 
134
135<a name="method14"></a>
136<p/><strong>bool Info::isLHA() &nbsp;</strong> <br/>
137has the process been generated from external Les Houches Accord
138information?
139 
140
141<a name="method15"></a>
142<p/><strong>bool Info::atEndOfFile() &nbsp;</strong> <br/>
143true if a linked Les Houches class refuses to return any further
144events, presumably because it has reached the end of the file from
145which events have been read in.
146 
147
148<a name="method16"></a>
149<p/><strong>bool Info::hasSub() &nbsp;</strong> <br/>
150does the process have a subprocess classification?
151Currently only true for minbias and Les Houches events, where it allows
152the hardest collision to be identified.
153 
154
155<a name="method17"></a>
156<p/><strong>string Info::nameSub() &nbsp;</strong> <br/>
157 
158<strong>int Info::codeSub() &nbsp;</strong> <br/>
159 
160<strong>int Info::nFinalSub() &nbsp;</strong> <br/>
161the name, code and number of final-state partons in the subprocess
162that occured when <code>hasSub()</code> is true. For a minimum-bias event
163the <code>code</code> would always be 101, while <code>codeSub()</code>
164would vary depending on the actual hardest interaction, e.g. 111 for
165<i>g g -> g g</i>. For a Les Houches event the <code>code</code> would
166always be 9999, while <code>codeSub()</code> would be the external
167user-defined classification code. The methods below would also provide
168information for such particular subcollisions. 
169 
170
171<h3>Hard process initiators</h3>
172
173The methods in this sections refer to the two initial partons of the
174hard <i>2 -> n</i> process (diffraction excluded; see below).
175
176<a name="method18"></a>
177<p/><strong>int Info::id1() &nbsp;</strong> <br/>
178 
179<strong>int Info::id2() &nbsp;</strong> <br/>
180the identities of the two partons coming in to the hard process.
181 
182
183<a name="method19"></a>
184<p/><strong>double Info::x1() &nbsp;</strong> <br/>
185 
186<strong>double Info::x2() &nbsp;</strong> <br/>
187<i>x</i> fractions of the two partons coming in to the hard process.
188 
189
190<a name="method20"></a>
191<p/><strong>double Info::y() &nbsp;</strong> <br/>
192 
193<strong>double Info::tau() &nbsp;</strong> <br/>
194rapidity and scaled mass-squared of the hard-process subsystem, as
195defined by the above <i>x</i> values.
196 
197
198<a name="method21"></a>
199<p/><strong>bool Info::isValence1() &nbsp;</strong> <br/>
200 
201<strong>bool Info::isValence2() &nbsp;</strong> <br/>
202<code>true</code> if the two hard incoming partons have been picked
203to belong to the valence piece of the parton-density distribution,
204else <code>false</code>. Should be interpreted with caution.
205Information is not set if you switch off parton-level processing.
206 
207
208<h3>Hard process parton densities and scales</h3>
209
210The methods in this section refer to the partons for which parton
211densities have been defined, in order to calculate the cross section
212of the hard process (diffraction excluded; see below).
213
214<p/>
215These partons would normally agree with the
216ones above, the initiators of the <i>2 -> n</i> process, but it
217does not have to be so. Currently the one counterexample is POWHEG
218events [<a href="Bibliography.php" target="page">Ali10</a>]. Here the original hard process could be
219<i>2 -> (n-1)</i>. The NLO machinery at times would add an
220initial-state branching to give a <i>2 -> n</i> process with a
221changed initial state. In that case the values in this section
222refer to the original <i>2 -> (n-1)</i> state and the initiator
223ones above to the complete<i>2 -> n</i> process. The
224<code>Info::list()</code> printout will contain a warning in such cases.
225
226<p/>
227For external events in the Les Houches format, the pdf information
228is obtained from the optional <code>#pdf</code> line. When this
229information is absent, the parton identities and <i>x</i> values agree
230with the initiator ones above, while the pdf values are unknown and
231therefore set to vanish. The <i>alpha_s</i> and <i>alpha_em</i>
232values are part of the compulsory information. The factorization and
233renormalization scales are both equated with the one compulsory scale
234value in the Les Houches standard, except when a <code>#pdf</code>
235line provides the factorization scale separately. If <i>alpha_s</i>,
236<i>alpha_em</i> or the compulsory scale value are negative at input
237then new values are defined as for internal processes. 
238
239<a name="method22"></a>
240<p/><strong>int Info::id1pdf() &nbsp;</strong> <br/>
241 
242<strong>int Info::id2pdf() &nbsp;</strong> <br/>
243the identities of the two partons for which parton density values
244are defined.
245 
246
247<a name="method23"></a>
248<p/><strong>double Info::x1pdf() &nbsp;</strong> <br/>
249 
250<strong>double Info::x2pdf() &nbsp;</strong> <br/>
251<i>x</i> fractions of the two partons for which parton density values
252are defined.
253 
254
255<a name="method24"></a>
256<p/><strong>double Info::pdf1() &nbsp;</strong> <br/>
257 
258<strong>double Info::pdf2() &nbsp;</strong> <br/>
259parton densities <i>x*f(x,Q^2)</i> evaluated for the two incoming
260partons; could be used e.g. for reweighting purposes in conjunction
261with the <code>idpdf</code>, <code>xpdf</code> and <code>QFac</code>
262methods. Events obtained from external programs or files may not
263contain this information and, if so, 0 is returned.
264 
265
266<a name="method25"></a>
267<p/><strong>double Info::QFac() &nbsp;</strong> <br/>
268 
269<strong>double Info::Q2Fac() &nbsp;</strong> <br/>
270the <i>Q</i> or <i>Q^2</i> factorization scale at which the
271densities were evaluated.
272 
273
274<a name="method26"></a>
275<p/><strong>double Info::alphaS() &nbsp;</strong> <br/>
276 
277<strong>double Info::alphaEM() &nbsp;</strong> <br/>
278the <i>alpha_strong</i> and <i>alpha_electromagnetic</i> values used
279for the hard process.
280 
281
282<a name="method27"></a>
283<p/><strong>double Info::QRen() &nbsp;</strong> <br/>
284 
285<strong>double Info::Q2Ren() &nbsp;</strong> <br/>
286the <i>Q</i> or <i>Q^2</i> renormalization scale at which
287<i>alpha_strong</i> and <i>alpha_electromagnetic</i> were evaluated.
288 
289
290<h3>Hard process kinematics</h3>
291
292The methods in this section provide info on the kinematics of the hard
293processes, with special emphasis on <i>2 -> 2</i> (diffraction excluded;
294see below).
295
296<a name="method28"></a>
297<p/><strong>double Info::mHat() &nbsp;</strong> <br/>
298 
299<strong>double Info::sHat() &nbsp;</strong> <br/>
300the invariant mass and its square for the hard process.
301 
302
303<a name="method29"></a>
304<p/><strong>double Info::tHat() &nbsp;</strong> <br/>
305 
306<strong>double Info::uHat() &nbsp;</strong> <br/>
307the remaining two Mandelstam variables; only defined for <i>2 -> 2</i>
308processes.
309 
310
311<a name="method30"></a>
312<p/><strong>double Info::pTHat() &nbsp;</strong> <br/>
313 
314<strong>double Info::pT2Hat() &nbsp;</strong> <br/>
315transverse momentum and its square in the rest frame of a <i>2 -> 2</i>
316processes.
317 
318
319<a name="method31"></a>
320<p/><strong>double Info::m3Hat() &nbsp;</strong> <br/>
321 
322<strong>double Info::m4Hat() &nbsp;</strong> <br/>
323the masses of the two outgoing particles in a <i>2 -> 2</i> processes.
324 
325
326<a name="method32"></a>
327<p/><strong>double Info::thetaHat() &nbsp;</strong> <br/>
328 
329<strong>double Info::phiHat() &nbsp;</strong> <br/>
330the polar and azimuthal scattering angles in the rest frame of
331a <i>2 -> 2</i> process.
332 
333
334<h3>Diffraction</h3>
335
336Information on the primary elastic or
337<?php $filepath = $_GET["filepath"];
338echo "<a href='Diffraction.php?filepath=".$filepath."' target='page'>";?>diffractive</a> process
339(<i>A B -> A B, X1 B, A X2, X1 X2, A X B</i>) can be obtained with
340the methods in the "Hard process kinematics" section above. The
341variables here obviously are <i>s, t, u, ...</i> rather than
342<i>sHat, tHat, uHat, ...</i>, but the method names remain to avoid
343unnecessary duplication. Most other methods are irrelevant for a
344primary elastic/diffractive process.
345
346<p/>Central diffraction <i>A B -> A X B</i> is a <i>2 -> 3</i>
347process, and therefore most of the <i>2 -> 2</i> variables are
348no longer relevant. The <code>tHat()</code> and <code>uHat()</code>
349methods instead return the two <i>t</i> values at the <i>A -> A</i>
350and <i>B -> B</i> vertices, and <code>pTHat()</code> the average
351transverse momentum of the three outgoing "particles", while
352<code>thetaHat()</code> and <code>phiHat()</code> are undefined.
353
354<p/>
355While the primary interaction does not contain a hard process,
356the diffractive subsystems can contain them, but need not.
357Specifically, double diffraction can contain two separate hard
358subprocesses, which breaks the methods above. Most of them have been
359expanded with an optional argument to address properties of diffractive
360subsystems. This argument can take four values:
361<ul>
362<li>0 : default argument, used for normal nondiffractive events or
363the primary elastic/diffractive process (see above);
364<li>1 : the <i>X1</i> system in single diffraction <i>A B -> X1 B</i>
365or double diffraction <i>A B -> X1 X2</i>;
366<li>2 : the <i>X2</i> system in single diffraction <i>A B -> A X2</i>
367or double diffraction <i>A B -> X1 X2</i>;
368<li>3 : the <i>X</i> system in central diffraction <i>A B -> A X B</i>.
369</ul>
370The argument is defined for all of the methods in the three sections above,
371"Hard process initiators", "Hard process parton densities and scales" and
372"Hard process kinematics", with the exception of the <code>isValence</code>
373methods. Also the four final methods of "The event type" section, the
374<code>...Sub()</code> methods, take this argument. But recall that they
375will only provide meaningful answers, firstly if there is a system of the
376requested type, and secondly if there is a hard subprocess in this system.
377A simple check for this is that <code>id1()</code> has to be nonvanishing.
378The methods below this section do not currently provide information
379specific to diffractive subsystems, e.g. the MPI information is not
380bookkept in such cases.   
381
382<h3>Event weight and activity</h3>
383
384<a name="method33"></a>
385<p/><strong>double Info::weight() &nbsp;</strong> <br/>
386weight assigned to the current event. Is normally 1 and thus
387uninteresting. However, there are several cases where one may have
388nontrivial event weights. These weights must the be used e.g. when
389filling histograms.
390<br/>(i) In the <code><?php $filepath = $_GET["filepath"];
391echo "<a href='PhaseSpaceCuts.php?filepath=".$filepath."' target='page'>";?>
392PhaseSpace:increaseMaximum = off</a></code> default strategy,
393an event with a differential cross-section above the assumed one
394(in a given phase-space point) is assigned a weight correspondingly
395above unity. This should happen only very rarely, if at all, and so
396could normally be disregarded.
397<br/>(ii) The <?php $filepath = $_GET["filepath"];
398echo "<a href='UserHooks.php?filepath=".$filepath."' target='page'>";?>User Hooks</a> class offers
399the possibility to bias the selection of phase space points, which
400means that events come with a compensating weight, stored here.
401<br/>(iii) For Les Houches events some strategies allow negative weights,
402which then after unweighting lead to events with weight -1. There are
403also Les Houches strategies where no unweighting is done, so events
404come with a weight. Specifically, for strategies <i>+4</i> and
405<i>-4</i>, the event weight is in units of pb. (Internally in mb,
406but converted at output.)
407 
408
409<a name="method34"></a>
410<p/><strong>double Info::weightSum() &nbsp;</strong> <br/>
411Sum of weights accumulated during the run. For unweighted events this
412agrees with the number of generated events. In order to obtain
413histograms normalized "per event", at the end of a run, histogram
414contents should be divided by this weight. (And additionally
415divided by the bin width.) Normalization to cross section also
416required multiplication by <code>sigmaGen()</code> below.
417 
418
419<a name="method35"></a>
420<p/><strong>int Info::lhaStrategy() &nbsp;</strong> <br/>
421normally 0, but if Les Houches events are input then it gives the
422event weighting strategy, see
423<?php $filepath = $_GET["filepath"];
424echo "<a href='LesHouchesAccord.php?filepath=".$filepath."' target='page'>";?>Les Houches Accord</a>.
425 
426
427<a name="method36"></a>
428<p/><strong>int Info::nISR() &nbsp;</strong> <br/>
429 
430<strong>int Info::nFSRinProc() &nbsp;</strong> <br/>
431 
432<strong>int Info::nFSRinRes() &nbsp;</strong> <br/>
433the number of emissions in the initial-state showering, in the final-state
434showering excluding resonance decys, and in the final-state showering
435inside resonance decays, respectively.
436 
437
438<a name="method37"></a>
439<p/><strong>double Info::pTmaxMPI() &nbsp;</strong> <br/>
440 
441<strong>double Info::pTmaxISR() &nbsp;</strong> <br/>
442 
443<strong>double Info::pTmaxFSR() &nbsp;</strong> <br/>
444Maximum <i>pT</i> scales set for MPI, ISR and FSR, given the
445process type and scale choice for the hard interactions. The actual
446evolution will run down from these scales.
447 
448
449<a name="method38"></a>
450<p/><strong>double Info::pTnow() &nbsp;</strong> <br/>
451The current <i>pT</i> scale in the combined MPI, ISR and FSR evolution.
452Useful for classification in <?php $filepath = $_GET["filepath"];
453echo "<a href='UserHooks.php?filepath=".$filepath."' target='page'>";?>user hooks</a>,
454but not once the event has been evolved. 
455 
456
457<a name="method39"></a>
458<p/><strong>double Info::mergingWeight() &nbsp;</strong> <br/>
459combined CKKW-L weight assigned to the current event. If CKKW-L merging is
460performed, all histograms should be filled with this weight, as discussed in
461 <a href="MatrixElementMerging.html" target="page"> Matrix Element
462Merging</a>.
463 
464
465<h3>Multiparton interactions</h3>
466
467<a name="method40"></a>
468<p/><strong>double Info::a0MPI() &nbsp;</strong> <br/>
469The value of a0 when an x-dependent matter profile is used,
470<code>MultipartonInteractions:bProfile = 4</code>.
471 
472
473<a name="method41"></a>
474<p/><strong>double Info::bMPI() &nbsp;</strong> <br/>
475The impact parameter <i>b</i> assumed for the current collision when
476multiparton interactions are simulated. Is not expressed in any physical
477size (like fm), but only rescaled so that the average should be unity
478for minimum-bias events (meaning less than that for events with hard
479processes).
480 
481
482<a name="method42"></a>
483<p/><strong>double Info::enhanceMPI() &nbsp;</strong> <br/>
484The choice of impact parameter implies an enhancement or depletion of
485the rate of subsequent interactions, as given by this number. Again
486the average is normalized be unity for minimum-bias events (meaning
487more than that for events with hard processes). 
488 
489
490<a name="method43"></a>
491<p/><strong>int Info::nMPI() &nbsp;</strong> <br/>
492The number of hard interactions in the current event. Is 0 for elastic
493and diffractive events, and else at least 1, with more possible from
494multiparton interactions.
495 
496
497<a name="method44"></a>
498<p/><strong>int Info::codeMPI(int i) &nbsp;</strong> <br/>
499 
500<strong>double Info::pTMPI(int i) &nbsp;</strong> <br/>
501the process code and transverse momentum of the <code>i</code>'th
502subprocess, with <code>i</code> in the range from 0 to
503<code>nMPI() - 1</code>. The values for subprocess 0 is redundant with
504information already provided above. 
505 
506
507<a name="method45"></a>
508<p/><strong>int Info::iAMPI(int i) &nbsp;</strong> <br/>
509 
510<strong>int Info::iBMPI(int i) &nbsp;</strong> <br/>
511are normally zero. However, if the <code>i</code>'th subprocess is
512a rescattering, i.e. either or both incoming partons come from the
513outgoing state of previous scatterings, they give the position in the
514event record of the outgoing-state parton that rescatters.
515<code>iAMPI</code> and <code>iBMPI</code> then denote partons coming from
516the first or second beam, respectively.
517 
518
519<a name="method46"></a>
520<p/><strong>double Info::eMPI(int i) &nbsp;</strong> <br/>
521The enhancement or depletion of the rate of the <code>i</code>'th
522subprocess. Is primarily of interest for the
523<code>MultipartonInteractions:bProfile = 4</code> option, where the
524size of the proton depends on the <i>x</i> values of the colliding
525partons. Note that <code>eMPI(0) = enhanceMPI()</code>.
526 
527
528<h3>Cross sections</h3>
529
530Here are the currently available methods related to the event sample
531as a whole, for the default value <code>i = 0</code>, and otherwise for
532the specific process code provided as argument. This is the number
533obtained with <code>Info::code()</code>, while the further subdivision
534given by <code>Info::codeSub()</code> is not bookkept. While continuously
535updated during the run, it is recommended only to study these properties
536at the end of the event generation, when the full statistics is available.
537The individual process results are not available if
538<?php $filepath = $_GET["filepath"];
539echo "<a href='ASecondHardProcess.php?filepath=".$filepath."' target='page'>";?>a second hard process</a> has beeen
540chosen, but can be gleaned from the <code>pythia.stat()</code> output.
541
542<a name="method47"></a>
543<p/><strong>long Info::nTried(int i = 0) &nbsp;</strong> <br/>
544 
545<strong>long Info::nSelected(int i = 0) &nbsp;</strong> <br/>
546 
547<strong>long Info::nAccepted(int i = 0) &nbsp;</strong> <br/>
548the total number of tried phase-space points, selected hard processes
549and finally accepted events, summed over all allowed processes
550(<code>i = 0</code>) or for the given process.
551The first number is only intended for a study of the phase-space selection
552efficiency. The last two numbers usually only disagree if the user introduces
553some veto during the event-generation process; then the former is the number
554of acceptable events found by PYTHIA and the latter the number that also
555were approved by the user. If you set <?php $filepath = $_GET["filepath"];
556echo "<a href='ASecondHardProcess.php?filepath=".$filepath."' target='page'>";?>a
557second hard process</a> there may also be a mismatch.
558 
559
560<a name="method48"></a>
561<p/><strong>double Info::sigmaGen(int i = 0) &nbsp;</strong> <br/>
562 
563<strong>double Info::sigmaErr(int i = 0) &nbsp;</strong> <br/>
564the estimated cross section and its estimated error,
565summed over all allowed processes (<code>i = 0</code>) or for the given
566process, in units of mb. The numbers refer to the accepted event sample
567above, i.e. after any user veto.
568 
569
570<h3>Loop counters</h3>
571
572Mainly for internal/debug purposes, a number of loop counters from
573various parts of the program are stored in the <code>Info</code> class,
574so that one can keep track of how the event generation is progressing.
575This may be especially useful in the context of the 
576<code><?php $filepath = $_GET["filepath"];
577echo "<a href='UserHooks.php?filepath=".$filepath."' target='page'>";?>User Hooks</a></code> facility.
578
579<a name="method49"></a>
580<p/><strong>int Info::getCounter(int i) &nbsp;</strong> <br/>
581the method that gives you access to the value of the various loop
582counters.
583<br/><code>argument</code><strong> i </strong>  :  the counter number you want to access:
584<br/><code>argumentoption </code><strong> 0 - 9</strong> :  counters that refer to the run as a whole,
585i.e. are set 0 at the beginning of the run and then only can increase.
586 
587<br/><code>argumentoption </code><strong> 0</strong> :  the number of successful constructor calls for the
588<code>Pythia</code> class (can only be 0 or 1).
589 
590<br/><code>argumentoption </code><strong> 1</strong> :  the number of times a <code>Pythia::init(...)</code>
591call has been begun. 
592 
593<br/><code>argumentoption </code><strong> 2</strong> :  the number of times a <code>Pythia::init(...)</code>
594call has been completed successfully. 
595 
596<br/><code>argumentoption </code><strong> 3</strong> :  the number of times a <code>Pythia::next()</code>
597call has been begun. 
598 
599<br/><code>argumentoption </code><strong> 4</strong> :  the number of times a <code>Pythia::next()</code>
600call has been completed successfully. 
601 
602<br/><code>argumentoption </code><strong> 10 - 19</strong> :  counters that refer to each individual event,
603and are reset and updated in the top-level <code>Pythia::next()</code>
604method. 
605 
606<br/><code>argumentoption </code><strong> 10</strong> :  the number of times the selection of a new hard
607process has been begun. Normally this should only happen once, unless a
608user veto is set to abort the current process and try a new one.
609 
610<br/><code>argumentoption </code><strong> 11</strong> :  the number of times the selection of a new hard
611process has been completed successfully. 
612 
613<br/><code>argumentoption </code><strong> 12</strong> :  as 11, but additionally the process should
614survive any user veto and go on to the parton- and hadron-level stages.
615 
616<br/><code>argumentoption </code><strong> 13</strong> :  as 11, but additionally the process should
617survive the parton- and hadron-level stage and any user cuts.
618 
619<br/><code>argumentoption </code><strong> 14</strong> :  the number of times the loop over parton- and
620hadron-level processing has begun for a hard process. Is reset each
621time counter 12 above is reached.
622 
623<br/><code>argumentoption </code><strong> 15</strong> :  the number of times the above loop has successfully
624completed the parton-level step.
625 
626<br/><code>argumentoption </code><strong> 16</strong> :  the number of times the above loop has successfully
627completed the checks and user vetoes after the parton-level step.
628 
629<br/><code>argumentoption </code><strong> 17</strong> :  the number of times the above loop has successfully
630completed the hadron-level step.
631 
632<br/><code>argumentoption </code><strong> 18</strong> :  the number of times the above loop has successfully
633completed the checks and user vetoes after the hadron-level step.
634 
635<br/><code>argumentoption </code><strong> 20 - 39</strong> :  counters that refer to a local part of the
636individual event, and are reset at the beginning of this part.
637 
638<br/><code>argumentoption </code><strong> 20</strong> :  the current system being processed in
639<code>PartonLevel::next()</code>. Is almost always 1, but for double
640diffraction the two diffractive systems are 1 and 2, respectively.
641 
642<br/><code>argumentoption </code><strong> 21</strong> :  the number of times the processing of the
643current system (see above) has begun.
644 
645<br/><code>argumentoption </code><strong> 22</strong> :  the number of times a step has begun in the
646combined MPI/ISR/FSR evolution downwards in <i>pT</i>
647for the current system.
648 
649<br/><code>argumentoption </code><strong> 23</strong> :  the number of times MPI has been selected for the
650downwards step above.
651 
652<br/><code>argumentoption </code><strong> 24</strong> :  the number of times ISR has been selected for the
653downwards step above.
654 
655<br/><code>argumentoption </code><strong> 25</strong> :  the number of times FSR has been selected for the
656downwards step above.
657 
658<br/><code>argumentoption </code><strong> 26</strong> :   the number of times MPI has been accepted as the
659downwards step above, after the vetoes.
660 
661<br/><code>argumentoption </code><strong> 27</strong> :   the number of times ISR has been accepted as the
662downwards step above, after the vetoes.
663 
664<br/><code>argumentoption </code><strong> 28</strong> :   the number of times FSR has been accepted as the
665downwards step above, after the vetoes.
666 
667<br/><code>argumentoption </code><strong> 29</strong> :  the number of times a step has begun in the
668separate (optional) FSR evolution downwards in <i>pT</i>
669for the current system.
670 
671<br/><code>argumentoption </code><strong> 30</strong> :  the number of times FSR has been selected for the
672downwards step above.
673 
674<br/><code>argumentoption </code><strong> 31</strong> :   the number of times FSR has been accepted as the
675downwards step above, after the vetoes.
676 
677<br/><code>argumentoption </code><strong> 40 - 49</strong> :  counters that are unused (currently), and
678that therefore are free to use, with the help of the two methods below.
679 
680 
681 
682
683<a name="method50"></a>
684<p/><strong>void Info::setCounter(int i, int value = 0) &nbsp;</strong> <br/>
685set the above counters to a given value. Only to be used by you
686for the unassigned counters 40 - 49.
687<br/><code>argument</code><strong> i </strong>  :  the counter number, see above.
688 
689<br/><code>argument</code><strong> value </strong> (<code>default = <strong>0</strong></code>) :  set the counter to this number;
690normally the default value is what you want.
691 
692 
693
694<a name="method51"></a>
695<p/><strong>void Info::addCounter(int i, int value = 0) &nbsp;</strong> <br/>
696increase the above counters by a given amount. Only to be used by you
697for the unassigned counters 40 - 49.
698<br/><code>argument</code><strong> i </strong>  :  the counter number, see above.
699 
700<br/><code>argument</code><strong> value </strong> (<code>default = <strong>1</strong></code>) :  increase the counter by this amount;
701normally the default value is what you want.
702 
703 
704
705<h3>Parton shower history</h3>
706
707The following methods are mainly intended for internal use,
708e.g. for matrix-element matching.
709
710<a name="method52"></a>
711<p/><strong>void Info::hasHistory(bool hasHistoryIn) &nbsp;</strong> <br/>
712 
713<strong>bool Info::hasHistory() &nbsp;</strong> <br/>
714set/get knowledge whether the likely shower history of an event
715has been traced.
716 
717
718<a name="method53"></a>
719<p/><strong>void Info::zNowISR(bool zNowIn) &nbsp;</strong> <br/>
720 
721<strong>double Info::zNowISR() &nbsp;</strong> <br/>
722set/get value of <i>z</i> in latest ISR branching.
723 
724
725<a name="method54"></a>
726<p/><strong>void Info::pT2NowISR(bool pT2NowIn) &nbsp;</strong> <br/>
727 
728<strong>double Info::pT2NowISR() &nbsp;</strong> <br/>
729set/get value of <i>pT^2</i> in latest ISR branching.
730 
731
732<h3>Header information</h3>
733
734A simple string key/value store, mainly intended for accessing
735information that is stored in the header block of Les Houches Event
736(LHE) files. In principle, any <code>LHAup</code> derived class can set
737this header information, which can then be read out later. Although the
738naming convention is arbitrary, in practice, it is dictated by the
739XML-like format of LHE files, see <?php $filepath = $_GET["filepath"];
740echo "<a href='LesHouchesAccord.php?filepath=".$filepath."' target='page'>";?>
741Les Houches Accord</a> for more details.
742
743<a name="method55"></a>
744<p/><strong>string Info::header(string key) &nbsp;</strong> <br/>
745return the header named <code>key</code>
746 
747
748<a name="method56"></a>
749<p/><strong>vector &lt;string&gt; Info::headerKeys() &nbsp;</strong> <br/>
750return a vector of all header key names
751 
752
753<a name="method57"></a>
754<p/><strong>void Info::setHeader(string key, string val) &nbsp;</strong> <br/>
755set the header named <code>key</code> with the contents of <code>val</code>
756 
757
758</body>
759</html>
760
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