3 <title>Program Flow</title>
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32 Recall that, to first order, the event generation process can be
33 subdivided into three stages:
35 <li>Initializaion.</li>
36 <li>The event loop.</li>
39 This is reflected in how the top-level <code>Pythia</code> class should
40 be used in the user-supplied main program, further outlined in the
41 following. Since the nature of the run is defined at the initialization
42 stage, this is where most of the PYTHIA user code has to be written.
43 So as not to confuse the reader unduly, the description of initialization
44 options has been subdivided into what would normally be used and what is
45 intended for more special applications.
48 At the bottom of this webpge is a complete survey of all public
49 <code>Pythia</code> methods and data members, in a more formal style
50 than the task-oriented descriptions found in the preceding sections.
51 This offers complementary information.
53 <h3>Initialization - normal usage</h3>
58 Already at the top of the main program file, you need to include the proper
63 To simplify typing, it also makes sense to declare
65 using namespace Pythia8;
71 The first step is to create a generator object,
76 It is this object that we will use from now on. Normally a run
77 will only contain one <code>Pythia</code> object. (But you can
78 use several <code>Pythia</code> objects, which then will be
79 independent of each other.)<br/>
80 By default all output from <code>Pythia</code> will be on the
81 <code>cout</code> stream, but the <code>list</code> methods below do
82 allow output to alternative streams or files.
87 You next want to set up the character of the run.
88 The pages under the "Setup Run Tasks" heading in the index
89 describe all the options available (with some very few exceptions,
90 found on the other pages).
91 The default values and your modifications are stored in two databases,
92 one for <?php $filepath = $_GET["filepath"];
93 echo "<a href='SettingsScheme.php?filepath=".$filepath."' target='page'>";?>generic settings</a>
94 and one for <?php $filepath = $_GET["filepath"];
95 echo "<a href='ParticleDataScheme.php?filepath=".$filepath."' target='page'>";?>particle data</a>.
96 Both of these are initialized with their default values by the
97 <code>Pythia</code> constructor. The default values can then be
98 changed, primarily by one of the two ways below, or by a combination
104 pythia.readString(string);
106 method repeatedly to do a change of a property at a time.
107 The information in the string is case-insensitive, but upper- and
108 lowercase can be combined for clarity. The rules are that<br/>
109 (i) if the first nonblank character of the string is a letter
110 it is assumed to contain a setting, and is sent on to
111 <code>pythia.settings.readString(string)</code>;<br/>
112 (ii) if instead the string begins with a digit it is assumed to
113 contain particle data updates, and so sent on to
114 <code>pythia.particleData.readString(string)</code>;<br/>
115 (iii) if none of the above, the string is assumed to be a comment,
116 i.e. nothing will be done.<br/>
117 In the former two cases, a warning is issued whenever a string
118 cannot be recognized (maybe because of a spelling mistake).<br/>
119 Some examples would be
121 pythia.readString("TimeShower:pTmin = 1.0");
122 pythia.readString("111:mayDecay = false");
124 The <code>readString(string)</code> method is intended primarily for
125 a few changes. It can also be useful if you want to construct a
126 parser for input files that contain commands both to PYTHIA and to
127 other libraries.<br/>
130 b) You can read in a file containing a list of those variables
131 you want to see changed, with a
133 pythia.readFile(fileName);
135 Each line in this file with be processes by the
136 <code>readString(string)</code> method introduced above. You can thus
137 freely mix comment lines and lines handed on to <code>Settings</code>
138 or to <code>ParticleData</code>.<br/>
139 This approach is better suited for more extensive changes than a direct
140 usage of <code>readString(string)</code>, and can also avoid having to
141 recompile and relink your main program between runs.<br/>
142 It is also possible to read input from an <code>istream</code>, by
143 default <code>cin</code>, rather than from a file. This may be convenient
144 if information is generated on-the-fly, within the same run.
147 Changes are made sequentially in the order the commands are encountered
148 during execution, meaning that if a parameter is changed several times
149 it is the last one that counts. The two special
150 <code><?php $filepath = $_GET["filepath"];
151 echo "<a href='Tunes.php?filepath=".$filepath."' target='page'>";?>Tune:ee</a></code> and
152 <code><?php $filepath = $_GET["filepath"];
153 echo "<a href='Tunes.php?filepath=".$filepath."' target='page'>";?>Tune:pp</a></code>
154 modes are expanded to change several settings in one go, but these obey
155 the same ordering rules.
161 Next comes the initialization stage, where all
162 remaining details of the generation are to be specified.
163 There is one standard method to use for this
166 <code>pythia.init();</code><br/>
167 with no arguments will read all relevant information from the
168 <code><?php $filepath = $_GET["filepath"];
169 echo "<a href='SettingsScheme.php?filepath=".$filepath."' target='page'>";?>Settings</a></code>
170 and <code><?php $filepath = $_GET["filepath"];
171 echo "<a href='ParticleDataScheme.php?filepath=".$filepath."' target='page'>";?>ParticleData</a></code>
172 databases. Specifically the setup of incoming beams and energies
173 is governed by the the beam parameters from the
174 <code><?php $filepath = $_GET["filepath"];
175 echo "<a href='BeamParameters.php?filepath=".$filepath."' target='page'>";?>Beams</a></code>
176 group of variables. If you don't change any of those you will
177 default to proton-proton collisions at 14 TeV, i.e. the nominal LHC
181 A few alternative forms are available, where the arguments of the
182 <code>init(...)</code> call can be used to set the beam parameters.
183 These alternatives are now deprecated, and will bew removed for
187 a) <code>pythia.init( idA, idB, eCM);</code><br/>
188 lets you specify the identities and the CM energy of the two incoming
189 beam particles, with A (B) assumed moving in the <i>+z (-z)</i>
193 b) <code>pythia.init( idA, idB, eA, eB);</code><br/>
194 is similar, but the two beam energies can be different, so the
195 collisions do not occur in the CM frame. If one of the beam energies
196 is below the particle mass you obtain a fixed-target topology.
199 c) <code>pythia.init( idA, idB, pxA, pyA, pzA, pxB, pyB, pzB);</code><br/>
200 is similar, but here you provide the three-momenta
201 <i>(p_x, p_y, p_z)</i> of the two incoming particles,
202 to allow for arbitrary beam directions.
205 d) <code>pythia.init(fileName);</code> <br/>
206 assumes a file in the <?php $filepath = $_GET["filepath"];
207 echo "<a href='LesHouchesAccord.php?filepath=".$filepath."' target='page'>";?>Les Houches
208 Event File</a> format is provided.
211 e) <code>pythia.init( LHAup*);</code> <br/>
212 assumes <?php $filepath = $_GET["filepath"];
213 echo "<a href='LesHouchesAccord.php?filepath=".$filepath."' target='page'>";?>Les Houches Accord</a>
214 initialization and event information is available in an <code>LHAup</code>
215 class object, and that a pointer to this object is handed in.
219 If you want to have a list of the generator and particle data used,
220 either only what has been changed or everything, you can use
222 pythia.settings.listChanged();
223 pythia.settings.listAll();
224 pythia.particleData.listChanged();
225 pythia.particleData.listAll();
231 <h3>The event loop</h3>
236 Inside the event generation loop you generate the
237 next event using the <code>next()</code> method,
241 This method takes no arguments; everything has already been specified.
242 It does return a bool value, however, <code>false</code> when the
243 generation failed. This can be a "programmed death" when the
244 supply of input parton-level configurations on file is exhausted.
245 It can alternatively signal a failure of <code>Pythia</code> to
246 generate an event, or unphysical features in the event record at the
247 end of the generation step. It makes sense to allow a few <code>false</code>
248 values before a run is aborted, so long as the related faulty
254 The generated event is now stored in the <code>event</code>
255 object, of type <code><?php $filepath = $_GET["filepath"];
256 echo "<a href='EventRecord.php?filepath=".$filepath."' target='page'>";?>Event</a></code>,
257 which is a public member of <code>pythia</code>. You therefore have
258 access to all the tools described on the pages under the "Study Output"
259 header in the index. For instance, an event can be listed with
260 <code>pythia.event.list()</code>, the identity of the <i>i</i>'th
261 <?php $filepath = $_GET["filepath"];
262 echo "<a href='ParticleProperties.php?filepath=".$filepath."' target='page'>";?>particle</a> is given by
263 <code>pythia.event[i].id()</code>, and so on.<br/>
264 The hard process - roughly the information normally stored in the
265 Les Houches Accord event record - is available as a second object,
266 <code>process</code>, also of type <code>Event</code>.<br/>
267 A third useful public object is
268 <code><?php $filepath = $_GET["filepath"];
269 echo "<a href='EventInformation.php?filepath=".$filepath."' target='page'>";?>info</a></code>, which offers
270 a set of one-of-a kind pieces of information about the most recent
280 <li>At the end of the generation process, you can call
284 to get some run statistics, on cross sections and the number of errors
285 and warnings encountered. The alternative
286 <code>pythia.statistics(...);</code> is equivalent but deprecated.
291 <h3>Advanced usage, mainly for initialization</h3>
293 A) Necessary data are automatically loaded when you use the
294 default PYTHIA installation directory structure and run the main
295 programs in the <code>examples</code> subdirectory. However, in the
296 general case, you must provide the path of the <code>xmldoc</code>
297 directory, where default settings and particle data are found.
298 This can be done in two ways.
303 You can set the environment variable <code>PYTHIA8DATA</code> to
304 contain the location of the <code>xmldoc</code> directory. In the
305 <code>csh</code> and <code>tcsh</code> shells this could e.g. be
307 setenv PYTHIA8DATA /home/myname/pythia81xx/xmldoc
309 while in other shells it could be
311 export PYTHIA8DATA=/home/myname/pythia81xx/xmldoc
313 where xx is the subversion number.<br/>
314 Recall that environment variables set locally are only defined in the
315 current instance of the shell. The above lines should go into your
316 <code>.cshrc</code> and <code>.bashrc</code> files, respectively,
317 if you want a more permanant assignment.
322 You can provide the path as argument to the <code>Pythia</code>
325 Pythia pythia("/home/myname/pythia81xx/xmldoc");
329 where again xx is the subversion number.<br/>
330 When <code>PYTHIA8DATA</code> is set it takes precedence, else
331 the path in the constructor is used, else one defaults to the
332 <code>../xmldoc</code> directory.
335 B) You can override the default behaviour of PYTHIA not only by the
336 settings and particle data, but also by replacing some of the
337 PYTHIA standard routines by ones of your own. Of course, this is only
338 possible if your routines fit into the general PYTHIA framework.
339 Therefore they must be coded according to the the rules relevant
340 in each case, as a derived class of a PYTHIA base class, and a pointer
341 to such an object must be handed in by one of the methods below.
342 These calls must be made before the <code>pythia.init(...)</code> call.
347 If you are not satisfied with the list of parton density functions that
348 are implemented internally or available via the LHAPDF interface
349 (see the <?php $filepath = $_GET["filepath"];
350 echo "<a href='PDFSelection.php?filepath=".$filepath."' target='page'>";?>PDF Selection</a> page), you
351 can suppy your own by a call to the <code>setPDFPtr(...)</code> method
353 pythia.setPDFptr( pdfAPtr, pdfBPtr);
355 where <code>pdfAPtr</code> and <code>pdfBPtr</code> are pointers to
356 two <code>Pythia</code> <?php $filepath = $_GET["filepath"];
357 echo "<a href='PartonDistributions.php?filepath=".$filepath."' target='page'>";?>PDF
358 objects</a>. Note that <code>pdfAPtr</code> and <code>pdfBPtr</code>
359 cannot point to the same object; even if the PDF set is the same,
360 two copies are needed to keep track of two separate sets of <i>x</i>
361 and density values.<br/>
362 If you further wish to use separate PDF's for the hard process of an
363 event than the ones being used for everything else, the extended form
365 pythia.setPDFptr( pdfAPtr, pdfBPtr, pdfHardAPtr, pdfHardBPtr);
367 allows you to specify those separately, and then the first two sets
368 would only be used for the showers and for multiparton interactions.
373 If you want to link to an external generator that feeds in events
374 in the LHA format, you can call the <code>setLHAupPtr(...)</code>
377 pythia.setLHAupPtr( lhaUpPtr);
379 where the <code>lhaUpPtr</code> derives from the
380 <?php $filepath = $_GET["filepath"];
381 echo "<a href='LesHouchesAccord.php?filepath=".$filepath."' target='page'>";?>LHAup</a> base class.
386 If you want to perform some particle decays with an
387 external generator, you can call the <code>setDecayPtr(...)</code>
390 pythia.setDecayPtr( decayHandlePtr, particles);
392 where the <code>decayHandlePtr</code> derives from the
393 <code><?php $filepath = $_GET["filepath"];
394 echo "<a href='ExternalDecays.php?filepath=".$filepath."' target='page'>";?>DecayHandler</a></code> base
395 class and <code>particles</code> is a vector of particle codes to be
401 If you want to use an external random number generator,
402 you can call the <code>setRndmEnginePtr(...)</code> method
404 pythia.setRndmEnginePtr( rndmEnginePtr);
406 where <code>rndmEnginePtr</code> derives from the
407 <code><?php $filepath = $_GET["filepath"];
408 echo "<a href='RandomNumbers.php?filepath=".$filepath."' target='page'>";?>RndmEngine</a></code> base class.
409 The <code>Pythia</code> default random number generator is perfectly
410 good, so this is only intended for consistency in bigger frameworks.
415 If you want to interrupt the evolution at various stages,
416 to interrogate the event and possibly veto it, or you want to
417 reweight the cross section, you can use
419 pythia.setUserHooksPtr( userHooksPtr);
421 where <code>userHooksPtr</code> derives from the
422 <code><?php $filepath = $_GET["filepath"];
423 echo "<a href='UserHooks.php?filepath=".$filepath."' target='page'>";?>UserHooks</a></code> base class.
428 If you want to use your own merging scale definition for
429 matrix element + parton shower merging, you can call
431 pythia.setMergingHooksPtr( mergingHooksPtr);
433 where <code>mergingHooksPtr</code> derives from the
434 <code><?php $filepath = $_GET["filepath"];
435 echo "<a href='MatrixElementMerging.php?filepath=".$filepath."' target='page'>";?>MergingHooks</a></code> base class.
440 If you want to use your own parametrization of beam momentum spread and
441 interaction vertex, rather than the provided simple Gaussian
442 parametrization (off by default), you can call
444 pythia.setBeamShapePtr( beamShapePtr);
446 where <code>beamShapePtr</code> derives from the
447 <code><?php $filepath = $_GET["filepath"];
448 echo "<a href='BeamShape.php?filepath=".$filepath."' target='page'>";?>BeamShape</a></code> base class.
453 If you want to implement a cross section of your own, but still make use
454 of the built-in phase space selection machinery, you can use
456 pythia.setSigmaPtr( sigmaPtr);
458 where <code>sigmaPtr</code> of type <code>SigmaProcess*</code> is an
459 instance of a class derived from one of the <code>Sigma1Process</code>,
460 <code>Sigma2Process</code> and <code>Sigma3Process</code> base classes
461 in their turn derived from
462 <code><?php $filepath = $_GET["filepath"];
463 echo "<a href='SemiInternalProcesses.php?filepath=".$filepath."' target='page'>";?>SigmaProcess</a></code>.
464 This call can be used repeatedly to hand in several different processes.
469 If your cross section contains the production of a new resonance
470 with known analytical expression for all the relevant partial widths,
471 you can make this resonance available to the program with
473 pythia.setResonancePtr( resonancePtr);
475 where <code>resonancePtr</code> of type <code>ResonanceWidths*</code>
476 is an instance of a class derived from the
477 <code><?php $filepath = $_GET["filepath"];
478 echo "<a href='SemiInternalResonances.php?filepath=".$filepath."' target='page'>";?>ResonanceWidths</a></code>
479 base class. In addition you need to add the particle to the normal
480 <?php $filepath = $_GET["filepath"];
481 echo "<a href='ParticleDataScheme.php?filepath=".$filepath."' target='page'>";?>particle and decay database</a>.
482 This procedure can be used repeatedly to hand in several different
488 If you are a real expert and want to <?php $filepath = $_GET["filepath"];
489 echo "<a href='ImplementNewShowers.php?filepath=".$filepath."' target='page'>";?>replace
490 the PYTHIA initial- and final-state showers</a>, you can use
492 pythia.setShowerPtr( timesDecPtr, timesPtr, spacePtr);
494 where <code>timesDecPtr</code> and <code>timesPtr</code>
495 derive from the <code>TimeShower</code> base class, and
496 <code>spacePtr</code> from <code>SpaceShower</code>.
502 C) Some comments on collecting several tasks in the same run.
506 PYTHIA has not been written for threadsafe execution on multicore
507 processors. If you want to use all cores,
508 the most efficient way presumably is to start correspondingly many jobs,
509 with different random number seeds, and add the statistics at the end.
510 However, note that several instances can be set up in the same main
511 program, since instances are completely independent of each other,
512 so each instance could be run inside a separate thread.
517 In some cases it is convenient to use more than one <code>Pythia</code>
518 object. The key example would be the simultaneous generation of signal
519 and pileup events, see <code>main19.cc</code>. The two objects are then
520 set up and initialized separately, and generate events completely
521 independently of each other. It is only afterwards that the event records
522 are combined into one single super-event per beam crossing.
527 When time is not an issue, it may be that you want to perform several
528 separate subruns sequentially inside a run, e.g. to combine results for
529 several kinematical regions or to compare results for some different
530 tunes of the underlying event. One way to go is to create (and destroy)
531 one <code>pythia</code> object for each subrun, in which case they are
532 completely separate. You can also use the same <code>pythia</code> object,
533 only doing a new <code>init(...)</code> call for each subrun. In that
534 case, the settings and particle databases remain as they were in the
535 previous subrun, only affected by the specific changes you introduced in
536 the meantime. You can put those changes in the main program, with
537 <code>pythia.readString(string)</code>, using your own logic to decide
538 which ones to execute in which subrun. A corresponding possibility
539 exists with <code>pythia.readFile(fileName, subrun)</code> (or an
540 <code>istream</code> instead of a <code>fileName</code>), which as second
541 argument can take a non-negative subrun number. Then only those
542 sections of the file before any <code>Main:subrun = ...</code> line
543 or with matching <code>subrun</code> number will be read. That is, the
544 file could have a structure like
546 ( lines always read, i.e. "default values" always (re)set )
548 ( lines only read with readFile(fileName, 1) )
550 ( lines only read with readFile(fileName, 2) )
552 Both of these possibilities are illustrated in <code>main08.cc</code>.
557 When working with Les Houches Event Files, it may well be that your
558 intended input event sample is spread over several files, that you all
559 want to turn into complete events in one and the same run. There is no
560 problem with looping over several subruns, where each new subrun
561 is initialized with a new file, with name set in <code>Beams:LHEF</code>.
562 However, in that case you will do a complete re-initialization each time
563 around. If you want to avoid this, note that the flag
564 <code>Beams:newLHEFsameInit = true</code> can be set for the second and
565 subsequent subruns. Then the new file will be simulated with the same
566 initialization data as already set in a previous
567 <code>pythia.init()</code> call. The burden rests on you to ensure
568 that this is indeed correct, e.g. that the two event samples have not
569 been generated for different beam energies. Also note that cross
570 sections for processes will be based on the information in the
571 first-read file, when the full initialization is performed.
576 <h2>The Pythia Class</h2>
578 Here follows the complete survey of all public <code>Pythia</code>
579 methods and data members.
581 <h3>Constructor and destructor</h3>
583 <a name="method1"></a>
584 <p/><strong>Pythia::Pythia(string xmlDir = "../xmldoc") </strong> <br/>
585 creates an instance of the <code>Pythia</code> event generators,
586 and sets initial default values, notably for all settings and
587 particle data. You may use several <code>Pythia</code> instances
588 in the same run; only when you want to access external static
589 libraries could this cause problems. (This includes in particular
590 Fortran libraries such as <?php $filepath = $_GET["filepath"];
591 echo "<a href='PDFSelection.php?filepath=".$filepath."' target='page'>";?>LHAPDF</a>.)
592 <br/><code>argument</code><strong> xmlDir </strong> (<code>default = <strong>../xmldoc</strong></code>) : allows you to choose
593 from which directory the default settings and particle data values
594 are read in. If the <code>PYTHIA8DATA</code> environment variable
595 has been set it takes precedence. Else this optional argument allows
596 you to choose another directory location than the default one. Note
597 that it is only the directory location you can change, its contents
598 must be the ones of the <code>xmldoc</code> directory in the
599 standard distribution.
603 <a name="method2"></a>
604 <p/><strong>Pythia::~Pythia </strong> <br/>
605 the destructor deletes the objects created by the constructor.
609 <a name="method3"></a>
610 <p/><strong>bool Pythia::readString(string line, bool warn = true) </strong> <br/>
611 reads in a single string, that is interpreted as an instruction to
612 modify the value of a <?php $filepath = $_GET["filepath"];
613 echo "<a href='SettingsScheme.php?filepath=".$filepath."' target='page'>";?>setting</a> or
614 <?php $filepath = $_GET["filepath"];
615 echo "<a href='ParticleDataScheme.php?filepath=".$filepath."' target='page'>";?>particle data</a>, as already described
617 <br/><code>argument</code><strong> line </strong> :
618 the string to be interpreted as an instruction.
620 <br/><code>argument</code><strong> warn </strong> (<code>default = <strong>true</strong></code>) :
621 write a warning message or not whenever the instruction does not make
622 sense, e.g. if the variable does not exist in the databases.
624 <br/><b>Note:</b> the method returns false if it fails to
625 make sense out of the string.
628 <a name="method4"></a>
629 <p/><strong>bool Pythia::readFile(string fileName, bool warn = true, int subrun = SUBRUNDEFAULT) </strong> <br/>
631 <strong>bool Pythia::readFile(string fileName, int subrun = SUBRUNDEFAULT) </strong> <br/>
633 <strong>bool Pythia::readFile(istream& inStream = cin, bool warn = true, int subrun = SUBRUNDEFAULT) </strong> <br/>
635 <strong>bool Pythia::readFile(istream& inStream = cin, int subrun = SUBRUNDEFAULT) </strong> <br/>
636 reads in a whole file, where each line is interpreted as an instruction
637 to modify the value of a <?php $filepath = $_GET["filepath"];
638 echo "<a href='SettingsScheme.php?filepath=".$filepath."' target='page'>";?>setting</a> or
639 <?php $filepath = $_GET["filepath"];
640 echo "<a href='ParticleDataScheme.php?filepath=".$filepath."' target='page'>";?>particle data</a>, cf. the above
641 <code>readString</code> method. All four forms of the
642 <code>readFile</code> command share code for actually reading a file.
643 <br/><code>argument</code><strong> fileName </strong> :
644 the file from which instructions are read.
646 <br/><code>argument</code><strong> inStream </strong> :
647 an istream from which instructions are read.
649 <br/><code>argument</code><strong> warn </strong> (<code>default = <strong>true</strong></code>) :
650 write a warning message or not whenever the instruction does not make
651 sense, e.g. if the variable does not exist in the databases. In the
652 command forms where <code>warn</code> is omitted it is true.
654 <br/><code>argument</code><strong> subrun </strong> :
655 allows you have several optional sets of commands within the same file.
656 Only those sections of the file before any <code>Main:subrun = ...</code>
657 line or following such a line with matching subrun number will be read.
658 The subrun number should not be negative; negative codes like
659 <code>SUBRUNDEFAULT</code> corresponds to no specific subrun.
661 <br/><b>Note:</b> the method returns false if it fails to
662 make sense out of any one line.
665 <a name="method5"></a>
666 <p/><strong>bool Pythia::setPDFPtr( PDF* pdfAPtr, PDF* pdfBPtr, PDF* pdfHardAPtr = 0, PDF* pdfHardBPtr = 0) </strong> <br/>
667 offers the possibility to link in external PDF sets for usage inside
668 the program. The rules for constructing your own class from
669 the <code>PDF</code> base class are described
670 <?php $filepath = $_GET["filepath"];
671 echo "<a href='PartonDistributions.php?filepath=".$filepath."' target='page'>";?>here</a>.
672 <br/><code>argument</code><strong> pdfAPtr, pdfBPtr </strong> :
673 pointers to two <code>PDF</code>-derived objects, one for each of
674 the incoming beams. The two objects have to be instantiated by you
675 in your program. Even if the two beam particles are the same
676 (protons, say) two separate instances are required, since current
677 information is cached in the objects. If both arguments are zero
678 then any previous linkage to external PDF's is disconnected,
679 see further Note 2 below.
681 <br/><code>argument</code><strong> pdfHardAPtr, pdfHardBPtr </strong> (<code>default = <strong>0</strong></code>) :
682 pointers to two further <code>PDF</code>-derived objects, one for each
683 of the incoming beams. Normally only the first two arguments above would
684 be used, and then the same PDF sets would be invoked everywhere. If you
685 provide these two further pointers then two different sets of PDF's are
686 used. This second set is then exclusively for the generation of the hard
687 process from the process matrix elements library. The first set above
688 is for everything else, notably parton showers and multiparton interactions.
690 <br/><b>Note 1:</b> The method returns false if the input is obviously
691 incorrect, e.g. if two (nonzero) pointers agree.
692 <br/><b>Note 2:</b> If you want to combine several subruns you can
693 call <code>setPDFPtr</code> with new arguments before each
694 <code>Pythia::init(...)</code> call. To revert from external PDF's
695 to the normal internal PDF selection you must call
696 <code>setPDFPtr(0, 0)</code> before <code>Pythia::init(...)</code>.
699 <a name="method6"></a>
700 <p/><strong>bool Pythia::setLHAupPtr( LHAup* lhaUpPtrIn) </strong> <br/>
701 offers linkage to an external generator that feeds in events
702 in the LHA format, see
703 <?php $filepath = $_GET["filepath"];
704 echo "<a href='LesHouchesAccord.php?filepath=".$filepath."' target='page'>";?>Les Houches Accord</a>,
706 <code><?php $filepath = $_GET["filepath"];
707 echo "<a href='BeamParameters.php?filepath=".$filepath."' target='page'>";?>Beams:frameType = 5</a></code>
709 <br/><code>argument</code><strong> lhaUpPtrIn </strong> :
710 pointer to a <code>LHAup</code>-derived object.
712 <br/><b>Note:</b> The method currently always returns true.
715 <a name="method7"></a>
716 <p/><strong>bool Pythia::setDecayPtr( DecayHandler* decayHandlePtr, vector<int> handledParticles) </strong> <br/>
717 offers the possibility to link to an external program that can do some
718 of the particle decays, instad of using the internal decay machinery.
719 With particles we here mean the normal hadrons and leptons, not
720 top quarks, electroweak bosons or new particles in BSM scenarios.
721 The rules for constructing your own class from the
722 <code>DecayHandler</code> base class are described
723 <?php $filepath = $_GET["filepath"];
724 echo "<a href='ExternalDecays.php?filepath=".$filepath."' target='page'>";?>here</a>. Note that you can only
725 provide one external object, but this object in its turn could
726 very well hand on different particles to separate decay libraries.
727 <br/><code>argument</code><strong> decayHandlePtr </strong> :
728 pointer to a <code>DecayHandler</code>-derived object. This object
729 must be instantiated by you in your program.
731 <br/><code>argument</code><strong> handledParticles </strong> : vector with the PDG identity codes
732 of the particles that should be handled by the external decay package.
733 You should only give the particle (positive) codes; the respective
734 antiparticle is always included as well.
736 <br/><b>Note:</b> The method currently always returns true.
739 <a name="method8"></a>
740 <p/><strong>bool Pythia::setRndmEnginePtr( RndmEngine* rndmEnginePtr) </strong> <br/>
741 offers the possibility to link to an external random number generator.
742 The rules for constructing your own class from the
743 <code>RndmEngine</code> base class are described
744 <?php $filepath = $_GET["filepath"];
745 echo "<a href='RandomNumbers.php?filepath=".$filepath."' target='page'>";?>here</a>.
746 <br/><code>argument</code><strong> rndmEnginePtr </strong> :
747 pointer to a <code>RndmEngine</code>-derived object. This object
748 must be instantiated by you in your program.
750 <br/><b>Note:</b> The method returns true if the pointer is different
754 <a name="method9"></a>
755 <p/><strong>bool Pythia::setUserHooksPtr( UserHooks* userHooksPtr) </strong> <br/>
756 offers the possibility to interact with the generation process at
757 a few different specified points, e.g. to reject undesirable events
758 at an early stage to save computer time. The rules for constructing
759 your own class from the <code>UserHooks</code> base class are described
760 <?php $filepath = $_GET["filepath"];
761 echo "<a href='UserHooks.php?filepath=".$filepath."' target='page'>";?>here</a>. You can only hand in one such
762 pointer, but this may be to a class that implements several of the
763 different allowed possibilities.
764 <br/><code>argument</code><strong> userHooksPtr </strong> :
765 pointer to a <code>userHooks</code>-derived object. This object
766 must be instantiated by you in your program.
768 <br/><b>Note:</b> The method currently always returns true.
771 <a name="method10"></a>
772 <p/><strong>bool Pythia::setBeamShapePtr( BeamShape* beamShapePtr) </strong> <br/>
773 offers the possibility to provide your own shape of the momentum and
774 space-time spread of the incoming beams. The rules for constructing
775 your own class from the <code>BeamShape</code> base class are described
776 <?php $filepath = $_GET["filepath"];
777 echo "<a href='BeamShape.php?filepath=".$filepath."' target='page'>";?>here</a>.
778 <br/><code>argument</code><strong> BeamShapePtr </strong> :
779 pointer to a <code>BeamShape</code>-derived object. This object
780 must be instantiated by you in your program.
782 <br/><b>Note:</b> The method currently always returns true.
785 <a name="method11"></a>
786 <p/><strong>bool Pythia::setSigmaPtr( SigmaProcess* sigmaPtr) </strong> <br/>
787 offers the possibility to link your own implementation of a process
788 and its cross section, to make it a part of the normal process
789 generation machinery, without having to recompile the
790 <code>Pythia</code> library itself. The rules for constructing your
791 own class from the <code>SigmaProcess</code> base class are described
792 <?php $filepath = $_GET["filepath"];
793 echo "<a href='SemiInternalProcesses.php?filepath=".$filepath."' target='page'>";?>here</a>. You may call this
794 routine repeatedly, to add as many new processes as you wish.
795 <br/><code>argument</code><strong> sigmaPtr </strong> :
796 pointer to a <code>SigmaProcess</code>-derived object. This object
797 must be instantiated by you in your program.
799 <br/><b>Note:</b> The method currently always returns true.
802 <a name="method12"></a>
803 <p/><strong>bool Pythia::setResonancePtr( ResonanceWidths* resonancePtr) </strong> <br/>
804 offers the possibility to link your own implementation of the
805 calculation of partial resonance widths, to make it a part of the
806 normal process generation machinery, without having to recompile the
807 <code>Pythia</code> library itself. This allows the decay of new
808 resonances to be handled internally, when combined with new particle
809 data. Note that the decay of normal hadrons cannot be modelled here;
810 this is for New Physics resonances. The rules for constructing your
811 own class from the <code>ResonanceWidths</code> base class are described
812 <?php $filepath = $_GET["filepath"];
813 echo "<a href='SemiInternalResonances.php?filepath=".$filepath."' target='page'>";?>here</a>. You may call this
814 routine repeatedly, to add as many new resonances as you wish.
815 <br/><code>argument</code><strong> resonancePtr </strong> :
816 pointer to a <code>ResonanceWidths</code>-derived object. This object
817 must be instantiated by you in your program.
819 <br/><b>Note:</b> The method currently always returns true.
822 <a name="method13"></a>
823 <p/><strong>bool Pythia::setShowerPtr( TimeShower* timesDecPtr, TimeShower* timesPtr = 0, SpaceShower* spacePtr = 0) </strong> <br/>
824 offers the possibility to link your own parton shower routines as
825 replacements for the default ones. This is much more complicated
826 since the showers are so central and are so interlinked with other
827 parts of the program. Therefore it is also possible to do the
828 replacement in stages, from the more independent to the more
829 intertwined. The rules for constructing your own classes from the
830 <code>TimeShower</code> and <code>SpaceShower</code>base classes
831 are described <?php $filepath = $_GET["filepath"];
832 echo "<a href='ImplementNewShowers.php?filepath=".$filepath."' target='page'>";?>here</a>. These
833 objects must be instantiated by you in your program.
834 <br/><code>argument</code><strong> timesDecPtr </strong> :
835 pointer to a <code>TimeShower</code>-derived object for doing
836 timelike shower evolution in resonance decays, e.g. of a
837 <i>Z^0</i>. This is decoupled from beam remnants and parton
838 distributions, and is therefore the simplest kind of shower
839 to write. If you provide a value 0 then the internal shower
840 routine will be used.
842 <br/><code>argument</code><strong> timesPtr </strong> (<code>default = <strong>0</strong></code>) :
843 pointer to a <code>TimeShower</code>-derived object for doing
844 all other timelike shower evolution, which is normally interleaved
845 with multiparton interactions and spacelike showers, introducing
846 both further physics and further technical issues. If you retain
847 the default value 0 then the internal shower routine will be used.
848 You are allowed to use the same pointer as above for the
849 <code>timesDecPtr</code> if the same shower can fulfill both tasks.
851 <br/><code>argument</code><strong> spacePtr </strong> (<code>default = <strong>0</strong></code>) :
852 pointer to a <code>SpaceShower</code>-derived object for doing
853 all spacelike shower evolution, which is normally interleaved
854 with multiparton interactions and timelike showers. If you retain
855 the default value 0 then the internal shower routine will be used.
857 <br/><b>Note:</b> The method currently always returns true.
862 At the initialization stage all the information provided above is
863 processed, and the stage is set up for the subsequent generation
864 of events. Currently several alterative forms of the <code>init</code>
865 method are available for this stage, but only the first one is
868 <a name="method14"></a>
869 <p/><strong>bool Pythia::init() </strong> <br/>
870 initialize for collisions, in any of the five separate possibilities
871 below. In this option the beams are not specified by input arguments,
872 but instead by the settings in the
873 <?php $filepath = $_GET["filepath"];
874 echo "<a href='BeamParameters.php?filepath=".$filepath."' target='page'>";?>Beam Parameters</a> section.
875 This allows the beams to be specified in the same file as other
876 run instructions. The default settings give pp collisions at 14 TeV.
877 <br/><b>Note:</b> The method returns false if the
878 initialization fails. It is then not possible to generate any
882 <a name="method15"></a>
883 <p/><strong>bool Pythia::init( int idA, int idB, double eCM) </strong> <br/>
884 initialize for collisions in the center-of-mass frame, with the
885 beams moving in the <i>+-z</i> directions.
886 <br/><code>argument</code><strong> idA, idB </strong> :
887 particle identity code for the two incoming beams.
889 <br/><code>argument</code><strong> eCM </strong> :
890 the CM energy of the collisions.
892 <br/><b>Notes:</b> Deprecated. The method returns false if the
893 initialization fails. It is then not possible to generate any
897 <a name="method16"></a>
898 <p/><strong>bool Pythia::init( int idA, int idB, double eA, double eB) </strong> <br/>
899 initialize for collisions with back-to-back beams,
900 moving in the <i>+-z</i> directions, but with different energies.
901 <br/><code>argument</code><strong> idA, idB </strong> :
902 particle identity code for the two incoming beams.
904 <br/><code>argument</code><strong> eA, eB </strong> :
905 the energies of the two beams. If an energy is set to be below
906 the mass of the respective beam particle that particle is taken to
907 be at rest. This offers a simple possibility to simulate
908 fixed-target collisions.
910 <br/><b>Notes:</b> Deprecated. The method returns false if the
911 initialization fails. It is then not possible to generate any
915 <a name="method17"></a>
916 <p/><strong>bool Pythia::init( int idA, int idB, double pxA, double pyA, double pzA, double pxB, double pyB, double pzB) </strong> <br/>
917 initialize for collisions with arbitrary beam directions.
918 <br/><code>argument</code><strong> idA, idB </strong> :
919 particle identity code for the two incoming beams.
921 <br/><code>argument</code><strong> pxA, pyA, pzA </strong> :
922 the three-momntum vector <i>(p_x, p_y, p_z)</i> of the first
925 <br/><code>argument</code><strong> pxB, pyB, pzB </strong> :
926 the three-momntum vector <i>(p_x, p_y, p_z)</i> of the second
929 <br/><b>Notes:</b> Deprecated. The method returns false if the
930 initialization fails. It is then not possible to generate any
934 <a name="method18"></a>
935 <p/><strong>bool Pythia::init( string LesHouchesEventFile, bool skipInit = false) </strong> <br/>
936 initialize for hard-process collisions fed in from an external file
937 with events, written according to the
938 <?php $filepath = $_GET["filepath"];
939 echo "<a href='LesHouchesAccord.php?filepath=".$filepath."' target='page'>";?>Les Houches Event File</a>
941 <br/><code>argument</code><strong> LesHouchesEventFile </strong> :
942 the file name (including path, where required) where the
943 events are stored, including relevant information on beam
944 identities and energies.
946 <br/><code>argument</code><strong> skipInit </strong> (<code>default = <strong>false</strong></code>) :
947 By default this method does a complete reinitialization of the
948 generation process. If you set this argument to true then
949 no reinitialization will occur, only the pointer to the event
950 file is updated. This may come in handy if the full event sample
951 is split across several files generated under the same conditions
952 (except random numbers, of course). You then do the first
953 initialization with the default, and all subsequent ones with
954 true. Note that things may go wrong if the files are not created
955 under the same conditions.
957 <br/><b>Notes:</b> Deprecated. The method returns false if the
958 initialization fails. It is then not possible to generate any
962 <a name="method19"></a>
963 <p/><strong>bool Pythia::init( LHAup* lhaUpPtr) </strong> <br/>
964 initialize for hard-process collisions fed in from an external
965 source of events, consistent with the Les Houches Accord standard.
966 The rules for constructing your own class from the <code>LHAup</code>
967 base class are described <?php $filepath = $_GET["filepath"];
968 echo "<a href='LesHouchesAccord.php?filepath=".$filepath."' target='page'>";?>here</a>.
969 This class is also required to provide the beam parameters.
970 <br/><code>argument</code><strong> lhaUpPtr </strong> :
971 pointer to a <code>LHAup</code>-derived object. This object
972 must be instantiated by you in your program.
974 <br/><b>Notes:</b> Deprecated. The method returns false if the
975 initialization fails. It is then not possible to generate any
979 <h3>Generate events</h3>
981 The <code>next()</code> method is the main one to generate events.
982 In this section we also put a few other specialized methods that
983 may be useful in some circumstances.
985 <a name="method20"></a>
986 <p/><strong>bool Pythia::next() </strong> <br/>
987 generate the next event. No input parameters are required; all
988 instructions have already been set up in the initialization stage.
989 <br/><b>Note:</b> The method returns false if the event generation
990 fails. The event record is then not consistent and should not be
991 studied. When reading in hard collisions from a Les Houches Event File
992 the problem may be that the end of the file has been reached. This
993 can be checked with the
994 <code><?php $filepath = $_GET["filepath"];
995 echo "<a href='EventInformation.php?filepath=".$filepath."' target='page'>";?>Info::atEndOfFile()</a></code>
999 <a name="method21"></a>
1000 <p/><strong>int Pythia::forceTimeShower( int iBeg, int iEnd, double pTmax, int nBranchMax = 0) </strong> <br/>
1001 perform a final-state shower evolution on partons in the
1002 <code>event</code> event record. This could be used for externally
1003 provided simple events, or even parts of events, for which
1004 a complete generation is not foreseen. Since the mother source of
1005 the parton system is not known, one cannot expect as good accuracy
1006 as in a normal generation. When two different timelike shower
1007 instances are set up, it is the one used for showering in resonance
1008 decays that is used here. The <code>forceTimeShower</code> method
1009 can be used in conjunction with the <code>forceHadronLevel</code>
1010 one below. Further comments are found
1011 <?php $filepath = $_GET["filepath"];
1012 echo "<a href='HadronLevelStandalone.php?filepath=".$filepath."' target='page'>";?>here</a>.
1013 <br/><code>argument</code><strong> iBeg, iEnd </strong> : the first and last entry of the event
1014 record to be affected by the call.
1016 <br/><code>argument</code><strong> pTmax </strong> : the maximum <i>pT</i> scale of emissions.
1017 Additionally, as always, the <code>scale</code> variable of each parton
1018 sets the maximum <i>pT</i> scale of branchings of this parton.
1019 Recall that this scale defaults to 0 if not set, so that no radiation
1022 <br/><code>argument</code><strong> nBranchMax </strong> (<code>default = <strong>0</strong></code>) : when positive, it sets the
1023 maximum number of branchings that are allowed to occur in the shower,
1024 i.e. the shower may stop evolving before reaching the lower cutoff.
1025 The argument has no effect when zero or negative, i.e. then the shower
1026 will continue to the lower cutoff.
1028 <br/><b>Note:</b> The method returns the number of branchings that
1032 <a name="method22"></a>
1033 <p/><strong>bool Pythia::forceHadronLevel(bool findJunctions = true) </strong> <br/>
1034 hadronize the existing event record, i.e. perform string fragmentation
1035 and particle decays. There are two main applications. Firstly,
1036 you can use the same parton-level content as a basis for repeated
1037 hadronization attempts, in schemes intended to save computer time.
1038 Secondly, you may have an external program that can simulate the full
1039 partonic level of the event - hard process, parton showers, multiparton
1040 interactions, beam remnants, colour flow, and so on - but not
1041 hadronization. Further details are found
1042 <?php $filepath = $_GET["filepath"];
1043 echo "<a href='HadronLevelStandalone.php?filepath=".$filepath."' target='page'>";?>here</a>.
1044 <br/><code>argument</code><strong> findJunctions </strong> (<code>default = <strong>true</strong></code>) :
1045 normally this routine will search through the event record and try to
1046 figure out if any colour junctions are present. If so, the colour
1047 topology of such junctions must be sorted out. In tricky cases this
1048 might fail, and then hadronization will not work. A user who is
1049 aware of this and knows the intended colour flow can set up the
1050 junction information in the event record, and then call
1051 <code>forceHadronLevel(false)</code> so as not to have this information
1053 <br/><b>Note:</b> The method returns false if the hadronization
1054 fails. The event record is then not consistent and should not be
1058 <a name="method23"></a>
1059 <p/><strong>bool Pythia::moreDecays() </strong> <br/>
1060 perform decays of all particles in the event record that have not been
1061 decayed but should have been done so. This can be used e.g. for
1062 repeated decay attempts, in schemes intended to save computer time.
1063 Further details are found <?php $filepath = $_GET["filepath"];
1064 echo "<a href='HadronLevelStandalone.php?filepath=".$filepath."' target='page'>";?>here</a>.
1065 <br/><b>Note:</b> The method returns false if the decays fail. The
1066 event record is then not consistent and should not be studied.
1069 <a name="method24"></a>
1070 <p/><strong>bool Pythia::forceRHadronDecays() </strong> <br/>
1071 perform decays of R-hadrons that were previously considered stable.
1072 This could be if an R-hadron is sufficiently long-lived that
1073 it may interact in the detector between production and decay, so that
1074 its four-momentum is changed. Further details are found
1075 <?php $filepath = $_GET["filepath"];
1076 echo "<a href='RHadrons.php?filepath=".$filepath."' target='page'>";?>here</a>.
1077 <br/><b>Note:</b> The method returns false if the decays fail. The
1078 event record is then not consistent and should not be studied.
1081 <a name="method25"></a>
1082 <p/><strong>void Pythia::LHAeventList(ostream& os = cout) </strong> <br/>
1083 list the Les Houches Accord information on the current event, see
1084 <code><?php $filepath = $_GET["filepath"];
1085 echo "<a href='LesHouchesAccord.php?filepath=".$filepath."' target='page'>";?>LHAup::listEvent(...)</a></code>.
1086 (Other listings are available via the class members below, so this
1087 listing is a special case that would not fit elsewhere.)
1088 <br/><code>argument</code><strong> os </strong> (<code>default = <strong>cout</strong></code>) :
1089 output stream where the listing occurs.
1093 <a name="method26"></a>
1094 <p/><strong>bool Pythia::LHAeventSkip(int nSkip) </strong> <br/>
1095 skip ahead a number of events in the Les Houches generation
1096 sequence, without doing anything further with them, see
1097 <code><?php $filepath = $_GET["filepath"];
1098 echo "<a href='LesHouchesAccord.php?filepath=".$filepath."' target='page'>";?>LHAup::skipEvent(nSkip)</a></code>.
1099 Mainly intended for debug purposes, e.g. when an event at a known
1100 location in a Les Houches Event File is causing problems.
1101 <br/><code>argument</code><strong> nSkip </strong> :
1102 number of events to skip.
1104 <br/><b>Note:</b> The method returns false if the operation fails,
1105 specifically if the end of a LHEF has been reached, cf.
1106 <code>next()</code> above.
1111 There is no required finalization step; you can stop generating events
1112 when and how you want. It is still recommended that you make it a
1113 routine to call the following method at the end. A second method provides
1114 a deprecated alternative.
1116 <a name="method27"></a>
1117 <p/><strong>void Pythia::stat() </strong> <br/>
1118 list statistics on the event generation, specifically total and partial
1119 cross sections and the number of different errors. For more details see
1120 <?php $filepath = $_GET["filepath"];
1121 echo "<a href='EventStatistics.php?filepath=".$filepath."' target='page'>";?>here</a> and for available options
1122 <?php $filepath = $_GET["filepath"];
1123 echo "<a href='MainProgramSettings.php?filepath=".$filepath."' target='page'>";?>here</a>.
1126 <a name="method28"></a>
1127 <p/><strong>void Pythia::statistics(bool all = false, bool reset = false) </strong> <br/>
1128 list statistics on the event generation, specifically total and partial
1129 cross sections and the number of different errors. For more details see
1130 <?php $filepath = $_GET["filepath"];
1131 echo "<a href='EventStatistics.php?filepath=".$filepath."' target='page'>";?>here</a>.
1132 <br/><code>argument</code><strong> all </strong> (<code>default = <strong>false</strong></code>) :
1133 if true also statistics on multiparton interactions is shown, by default not.
1135 <br/><code>argument</code><strong> reset </strong> (<code>default = <strong>false</strong></code>) : if true then all counters,
1136 e.g on events generated and errors experienced, are reset to zero
1137 whenever the routine is called. The default instead is that
1138 all stored statistics information is unaffected by the call. Counters
1139 are automatically reset in each new <code>Pythia::init(...)</code>
1140 call, however, so the only time the <code>reset</code> option makes a
1141 difference is if <code>statistics(...)</code> is called several times
1144 <br/><b>Note:</b> Deprecated.
1147 <h3>Interrogate settings</h3>
1149 Normally settings are used in the setup and initialization stages
1150 to determine the character of a run, e.g. read from a file with the
1151 above-described <code>Pythia::readFile(...)</code> method.
1152 There is no strict need for a user to interact with the
1153 <code>Settings</code> database in any other way. However, as an option,
1154 some settings variables have been left free for the user to set in
1155 such a file, and then use in the main program to directly affect the
1156 performance of that program, see
1157 <?php $filepath = $_GET["filepath"];
1158 echo "<a href='MainProgramSettings.php?filepath=".$filepath."' target='page'>";?>here</a>. A typical example would
1159 be the number of events to generate. For such applications the
1160 following shortcuts to some <code>Settings</code> methods may be
1163 <a name="method29"></a>
1164 <p/><strong>bool Pythia::flag(string key) </strong> <br/>
1165 read in a boolean variable from the <code>Settings</code> database.
1166 <br/><code>argument</code><strong> key </strong> :
1167 the name of the variable to be read.
1171 <a name="method30"></a>
1172 <p/><strong>int Pythia::mode(string key) </strong> <br/>
1173 read in an integer variable from the <code>Settings</code> database.
1174 <br/><code>argument</code><strong> key </strong> :
1175 the name of the variable to be read.
1179 <a name="method31"></a>
1180 <p/><strong>double Pythia::parm(string key) </strong> <br/>
1181 read in a double-precision variable from the <code>Settings</code>
1183 <br/><code>argument</code><strong> key </strong> :
1184 the name of the variable to be read.
1188 <a name="method32"></a>
1189 <p/><strong>string Pythia::word(string key) </strong> <br/>
1190 read in a string variable from the <code>Settings</code> database.
1191 <br/><code>argument</code><strong> key </strong> :
1192 the name of the variable to be read.
1196 <h3>Data members</h3>
1198 The <code>Pythia</code> class contains a few public data members,
1199 several of which play a central role. We list them here, with
1200 links to the places where they are further described.
1202 <a name="method33"></a>
1203 <p/><strong>Event Pythia::process </strong> <br/>
1204 the hard-process event record, see <?php $filepath = $_GET["filepath"];
1205 echo "<a href='EventRecord.php?filepath=".$filepath."' target='page'>";?>here</a>
1206 for further details.
1209 <a name="method34"></a>
1210 <p/><strong>Event Pythia::event </strong> <br/>
1211 the complete event record, see <?php $filepath = $_GET["filepath"];
1212 echo "<a href='EventRecord.php?filepath=".$filepath."' target='page'>";?>here</a>
1213 for further details.
1216 <a name="method35"></a>
1217 <p/><strong>Info Pythia::info </strong> <br/>
1218 further information on the event-generation process, see
1219 <?php $filepath = $_GET["filepath"];
1220 echo "<a href='EventInformation.php?filepath=".$filepath."' target='page'>";?>here</a> for further details.
1223 <a name="method36"></a>
1224 <p/><strong>Settings Pythia::settings </strong> <br/>
1225 the settings database, see <?php $filepath = $_GET["filepath"];
1226 echo "<a href='SettingsScheme.php?filepath=".$filepath."' target='page'>";?>here</a>
1227 for further details.
1230 <a name="method37"></a>
1231 <p/><strong>ParticleData Pythia::particleData </strong> <br/>
1232 the particle properties and decay tables database, see
1233 <?php $filepath = $_GET["filepath"];
1234 echo "<a href='ParticleDataScheme.php?filepath=".$filepath."' target='page'>";?>here</a> for further details.
1237 <a name="method38"></a>
1238 <p/><strong>Rndm Pythia::rndm </strong> <br/>
1239 the random number generator, see <?php $filepath = $_GET["filepath"];
1240 echo "<a href='RandomNumberSeed.php?filepath=".$filepath."' target='page'>";?>here</a>
1241 and <?php $filepath = $_GET["filepath"];
1242 echo "<a href='RandomNumbers.php?filepath=".$filepath."' target='page'>";?>here</a> for further details.
1245 <a name="method39"></a>
1246 <p/><strong>CoupSM Pythia::coupSM </strong> <br/>
1247 Standard Model couplings and mixing matrices, see
1248 <?php $filepath = $_GET["filepath"];
1249 echo "<a href='StandardModelParameters.php?filepath=".$filepath."' target='page'>";?>here</a> for further details.
1252 <a name="method40"></a>
1253 <p/><strong>SusyLesHouches Pythia::slha </strong> <br/>
1254 parameters and particle data in the context of supersymmetric models,
1255 see <?php $filepath = $_GET["filepath"];
1256 echo "<a href='SUSYLesHouchesAccord.php?filepath=".$filepath."' target='page'>";?>here</a> for further details.
1259 <a name="method41"></a>
1260 <p/><strong>PartonSystems Pythia::partonSystems </strong> <br/>
1261 a grouping of the partons in the event record by subsystem,
1262 see <?php $filepath = $_GET["filepath"];
1263 echo "<a href='AdvancedUsage.php?filepath=".$filepath."' target='page'>";?>here</a> for further details.
1269 <!-- Copyright (C) 2012 Torbjorn Sjostrand -->