3 <title>Particle Properties</title>
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30 <h2>Particle Properties</h2>
32 A <code>Particle</code> corresponds to one entry/slot in the
33 event record. Its properties therefore is a mix of ones belonging
34 to a particle-as-such, like its identity code or four-momentum,
35 and ones related to the event-as-a-whole, like which mother it has.
38 What is stored for each particle is
40 <li>the identity code,</li>
41 <li>the status code,</li>
42 <li>two mother indices,</li>
43 <li>two daughter indices,</li>
44 <li>a colour and an anticolour index,</li>
45 <li>the four-momentum and mass,</li>
46 <li>the scale at which the particle was produced (optional),</li>
47 <li>the production vertex and proper lifetime (optional),</li>
48 <li>a pointer to the particle kind in the particle data table, and</li>
49 <li>a pointer to the whole particle data table.</li>
51 From these, a number of further quantities may be derived.
53 <h3>Basic output methods</h3>
55 The following member functions can be used to extract the most important
58 <a name="method1"></a>
59 <p/><strong>int Particle::id() </strong> <br/>
60 the identity of a particle, according to the PDG particle codes
61 [<a href="Bibliography.php" target="page">Yao06</a>].
64 <a name="method2"></a>
65 <p/><strong>int Particle::status() </strong> <br/>
66 status code. The status code includes information on how a particle was
67 produced, i.e. where in the program execution it was inserted into the
68 event record, and why. It also tells whether the particle is still present
69 or not. It does not tell how a particle disappeared, whether by a decay,
70 a shower branching, a hadronization process, or whatever, but this is
71 implicit in the status code of its daughter(s). The basic scheme is:
73 <li>status = +- (10 * i + j)</li>
74 <li> + : still remaining particles</li>
75 <li> - : decayed/branched/fragmented/... and not remaining</li>
76 <li> i = 1 - 9 : stage of event generation inside PYTHIA</li>
77 <li> i = 10 -19 : reserved for future expansion</li>
78 <li> i >= 20 : free for add-on programs</li>
79 <li> j = 1 - 9 : further specification</li>
81 In detail, the list of used or foreseen status codes is:
83 <li>11 - 19 : beam particles</li>
85 <li>11 : the event as a whole</li>
86 <li>12 : incoming beam</li>
87 <li>13 : incoming beam-inside-beam (e.g. <i>gamma</i>
89 <li>14 : outgoing elastically scattered</li>
90 <li>15 : outgoing diffractively scattered</li>
92 <li>21 - 29 : particles of the hardest subprocess</li>
94 <li>21 : incoming</li>
95 <li>22 : intermediate (intended to have preserved mass)</li>
96 <li>23 : outgoing</li>
98 <li>31 - 39 : particles of subsequent subprocesses</li>
100 <li>31 : incoming</li>
101 <li>32 : intermediate (intended to have preserved mass)</li>
102 <li>33 : outgoing</li>
103 <li>34 : incoming that has already scattered</li>
105 <li>41 - 49 : particles produced by initial-state-showers</li>
107 <li>41 : incoming on spacelike main branch</li>
108 <li>42 : incoming copy of recoiler</li>
109 <li>43 : outgoing produced by a branching</li>
110 <li>44 : outgoing shifted by a branching</li>
111 <li>45 : incoming rescattered parton, with changed kinematics
112 owing to ISR in the mother system (cf. status 34)</li>
113 <li>46 : incoming copy of recoiler when this is a rescattered
114 parton (cf. status 42)</li>
116 <li>51 - 59 : particles produced by final-state-showers</li>
118 <li>51 : outgoing produced by parton branching</li>
119 <li>52 : outgoing copy of recoiler, with changed momentum</li>
120 <li>53 : copy of recoiler when this is incoming parton,
121 with changed momentum</li>
122 <li>54 : copy of a recoiler, when in the initial state of a
123 different system from the radiator</li>
124 <li>55 : copy of a recoiler, when in the final state of a
125 different system from the radiator</li>
127 <li>61 - 69 : particles produced by beam-remnant treatment</li>
129 <li>61 : incoming subprocess particle with primordial <i>kT</i>
131 <li>62 : outgoing subprocess particle with primordial <i>kT</i>
133 <li>63 : outgoing beam remnant</li>
135 <li>71 - 79 : partons in preparation of hadronization process</li>
137 <li>71 : copied partons to collect into contiguous colour singlet</li>
138 <li>72 : copied recoiling singlet when ministring collapses to
139 one hadron and momentum has to be reshuffled</li>
140 <li>73 : combination of very nearby partons into one</li>
141 <li>74 : combination of two junction quarks (+ nearby gluons)
143 <li>75 : gluons split to decouple a junction-antijunction pair</li>
144 <li>76 : partons with momentum shuffled to decouple a
145 junction-antijunction pair </li>
146 <li>77 : temporary opposing parton when fragmenting first two
147 strings in to junction (should disappear again)</li>
148 <li>78 : temporary combined diquark end when fragmenting last
149 string in to junction (should disappear again)</li>
151 <li>81 - 89 : primary hadrons produced by hadronization process</li>
153 <li>81 : from ministring into one hadron</li>
154 <li>82 : from ministring into two hadrons</li>
155 <li>83, 84 : from normal string (the difference between the two
156 is technical, whether fragmented off from the top of the
157 string system or from the bottom, useful for debug only)</li>
158 <li>85, 86 : primary produced hadrons in junction frogmentation of
159 the first two string legs in to the junction,
160 in order of treatment</li>
162 <li>91 - 99 : particles produced in decay process, or by Bose-Einstein
165 <li>91 : normal decay products</li>
166 <li>92 : decay products after oscillation <i>B0 <-> B0bar</i> or
167 <i>B_s0 <-> B_s0bar</i></li>
168 <li>93, 94 : decay handled by external program, normally
169 or with oscillation</li>
170 <li>99 : particles with momenta shifted by Bose-Einstein effects
171 (not a proper decay, but bookkept as an <i>1 -> 1</i> such,
172 happening after decays of short-lived resonances but before
173 decays of longer-lived particles)</li>
175 <li>101 - 199 : reserved for future expansion</li>
176 <li>201 - : free to be used by anybody</li>
180 <a name="method3"></a>
181 <p/><strong>int Particle::mother1() </strong> <br/>
183 <strong>int Particle::mother2() </strong> <br/>
184 the indices in the event record where the first and last mothers are
185 stored, if any. There are five allowed combinations of <code>mother1</code>
186 and <code>mother2</code>:
188 <li><code>mother1 = mother2 = 0</code>: for lines 0 - 2, where line 0
189 represents the event as a whole, and 1 and 2 the two incoming
190 beam particles; </li>
191 <li><code>mother1 = mother2 > 0</code>: the particle is a "carbon copy"
192 of its mother, but with changed momentum as a "recoil" effect,
193 e.g. in a shower;</li>
194 <li><code>mother1 > 0, mother2 = 0</code>: the "normal" mother case, where
195 it is meaningful to speak of one single mother to several products,
196 in a shower or decay;</li>
197 <li><code>mother1 < mother2</code>, both > 0, for
198 <code>abs(status) = 81 - 86</code>: primary hadrons produced from the
199 fragmentation of a string spanning the range from <code>mother1</code>
200 to <code>mother2</code>, so that all partons in this range should be
201 considered mothers;</li>
202 <li><code>mother1 < mother2</code>, both > 0, except case 4: particles
203 with two truly different mothers, in particular the particles emerging
204 from a hard <i>2 -> n</i> interaction.</li>
206 <br/><b>Note 1:</b> in backwards evolution of initial-state showers,
207 the mother may well appear below the daughter in the event record.
208 <br/><b>Note 2:</b> the <code>motherList(i)</code> method of the
209 <code>Event</code> class returns a vector of all the mothers,
210 providing a uniform representation for all five cases.
213 <a name="method4"></a>
214 <p/><strong>int Particle::daughter1() </strong> <br/>
216 <strong>int Particle::daughter2() </strong> <br/>
217 the indices in the event record where the first and last daughters
218 are stored, if any. There are five allowed combinations of
219 <code>daughter1</code> and <code>daughter2</code>:
221 <li><code>daughter1 = daughter2 = 0</code>: there are no daughters
223 <li><code>daughter1 = daughter2 > 0</code>: the particle has a
224 "carbon copy" as its sole daughter, but with changed momentum
225 as a "recoil" effect, e.g. in a shower;</li>
226 <li><code>daughter1 > 0, daughter2 = 0</code>: each of the incoming beams
227 has only (at most) one daughter, namely the initiator parton of the
228 hardest interaction; further, in a <i>2 -> 1</i> hard interaction,
229 like <i>q qbar -> Z^0</i>, or in a clustering of two nearby partons,
230 the initial partons only have this one daughter;</li>
231 <li><code>daughter1 < daughter2</code>, both > 0: the particle has
232 a range of decay products from <code>daughter1</code> to
233 <code>daughter2</code>;</li> <li><code>daughter2 < daughter1</code>,
234 both > 0: the particle has two separately stored decay products (e.g.
235 in backwards evolution of initial-state showers).</li>
237 <br/><b>Note 1:</b> in backwards evolution of initial-state showers, the
238 daughters may well appear below the mother in the event record.
239 <br/><b>Note 2:</b> the mother-daughter relation normally is reciprocal,
240 but not always. An example is hadron beams (indices 1 and 2), where each
241 beam remnant and the initiator of each multiple interaction has the
242 respective beam as mother, but the beam itself only has the initiator
243 of the hardest interaction as daughter.
244 <br/><b>Note 3:</b> the <code>daughterList(i)</code> method of the
245 <code>Event</code> class returns a vector of all the daughters,
246 providing a uniform representation for all five cases. With this method,
247 also all the daughters of the beams are caught, with the initiators of
248 the basic process given first, while the rest are in no guaranteed order
249 (since they are found by a scanning of the event record for particles
250 with the beam as mother, with no further information).
253 <a name="method5"></a>
254 <p/><strong>int Particle::col() </strong> <br/>
256 <strong>int Particle::acol() </strong> <br/>
257 the colour and anticolour tags, Les Houches Accord [<a href="Bibliography.php" target="page">Boo01</a>]
258 style (starting from tag 101 by default, see below).
261 <a name="method6"></a>
262 <p/><strong>double Particle::px() </strong> <br/>
264 <strong>double Particle::py() </strong> <br/>
266 <strong>double Particle::pz() </strong> <br/>
268 <strong>double Particle::e() </strong> <br/>
269 the particle four-momentum components.
272 <a name="method7"></a>
273 <p/><strong>Vec4 Particle::p() </strong> <br/>
274 the particle four-momentum vector, with components as above.
277 <a name="method8"></a>
278 <p/><strong>double Particle::m() </strong> <br/>
279 the particle mass, stored with a minus sign (times the absolute value)
280 for spacelike virtual particles.
283 <a name="method9"></a>
284 <p/><strong>double Particle::scale() </strong> <br/>
285 the scale at which a parton was produced, which can be used to restrict
286 its radiation to lower scales in subsequent steps of the shower evolution.
287 Note that scale is linear in momenta, not quadratic (i.e. <i>Q</i>,
291 <a name="method10"></a>
292 <p/><strong>double Particle::xProd() </strong> <br/>
294 <strong>double Particle::yProd() </strong> <br/>
296 <strong>double Particle::zProd() </strong> <br/>
298 <strong>double Particle::tProd() </strong> <br/>
299 the production vertex coordinates, in mm or mm/c.
302 <a name="method11"></a>
303 <p/><strong>Vec4 Particle::vProd() </strong> <br/>
304 The production vertex four-vector. Note that the components of a
305 <code>Vec4</code> are named <code>px(), py(), pz() and e()</code>
306 which of course then should be reinterpreted as above.
309 <a name="method12"></a>
310 <p/><strong>double Particle::tau() </strong> <br/>
311 the proper lifetime, in mm/c. It is assigned for all hadrons with
312 positive nominal <i>tau</i>, <i>tau_0 > 0</i>, because it can be used
313 by PYTHIA to decide whether a particle should or should not be allowed
314 to decay, e.g. based on the decay vertex distance to the primary interaction
318 <h3>Input methods</h3>
320 The same method names as above are also overloaded in versions that
321 set values. These have an input argument of the same type as the
322 respective output above, and are of type <code>void</code>.
325 There are also a few alternative methods for input:
327 <a name="method13"></a>
328 <p/><strong>void Particle::statusPos() </strong> <br/>
330 <strong>void Particle::statusNeg() </strong> <br/>
331 sets the status sign positive or negative, without changing the absolute value.
334 <a name="method14"></a>
335 <p/><strong>void Particle::statusCode(int code) </strong> <br/>
336 changes the absolute value but retains the original sign.
339 <a name="method15"></a>
340 <p/><strong>void Particle::mothers(int mother1, int mother2) </strong> <br/>
341 sets both mothers in one go.
344 <a name="method16"></a>
345 <p/><strong>void Particle::daughters(int daughter1, int daughter2) </strong> <br/>
346 sets both daughters in one go.
349 <a name="method17"></a>
350 <p/><strong>void Particle::cols(int col, int acol) </strong> <br/>
351 sets both colour and anticolour in one go.
354 <a name="method18"></a>
355 <p/><strong>void Particle::p(double px, double py, double pz, double e) </strong> <br/>
356 sets the four-momentum components in one go.
359 <a name="method19"></a>
360 <p/><strong>void Particle::vProd(double xProd, double yProd, double zProd, double tProd) </strong> <br/>
361 sets the production vertex components in one go.
364 <h3>Further output methods</h3>
367 In addition, a number of derived quantities can easily be obtained,
368 but cannot be set, such as:
370 <a name="method20"></a>
371 <p/><strong>int Particle::idAbs() </strong> <br/>
372 the absolute value of the particle identity code.
375 <a name="method21"></a>
376 <p/><strong>int Particle::statusAbs() </strong> <br/>
377 the absolute value of the status code.
380 <a name="method22"></a>
381 <p/><strong>bool Particle::isFinal() </strong> <br/>
382 true for a remaining particle, i.e. one with positive status code,
383 else false. Thus, after an event has been fully generated, it
384 separates the final-state particles from intermediate-stage ones.
385 (If used earlier in the generation process, a particle then
386 considered final may well decay later.)
389 <a name="method23"></a>
390 <p/><strong>bool Particle::isRescatteredIncoming() </strong> <br/>
391 true for particles with a status code -34, -45, -46 or -54, else false.
392 This singles out partons that have been created in a previous
393 scattering but here are bookkept as belonging to the incoming state
394 of another scattering.
397 <a name="method24"></a>
398 <p/><strong>bool Particle::hasVertex() </strong> <br/>
399 production vertex has been set; if false then production at the origin
403 <a name="method25"></a>
404 <p/><strong>double Particle::m2() </strong> <br/>
405 squared mass, which can be negative for spacelike partons.
408 <a name="method26"></a>
409 <p/><strong>double Particle::mCalc() </strong> <br/>
411 <strong>double Particle::m2Calc() </strong> <br/>
412 (squared) mass calculated from the four-momentum; should agree
413 with <code>m(), m2()</code> up to roundoff. Negative for spacelike
417 <a name="method27"></a>
418 <p/><strong>double Particle::eCalc() </strong> <br/>
419 energy calculated from the mass and three-momentum; should agree
420 with <code>e()</code> up to roundoff. For spacelike partons a
421 positive-energy solution is picked. This need not be the correct
422 one, so it is recommended not to use the method in such cases.
425 <a name="method28"></a>
426 <p/><strong>double Particle::pT() </strong> <br/>
428 <strong>double Particle::pT2() </strong> <br/>
429 (squared) transverse momentum.
432 <a name="method29"></a>
433 <p/><strong>double Particle::mT() </strong> <br/>
435 <strong>double Particle::mT2() </strong> <br/>
436 (squared) transverse mass. If <i>m_T^2</i> is negative, which can happen
437 for a spacelike parton, then <code>mT()</code> returns
438 <i>-sqrt(-m_T^2)</i>, by analogy with the negative sign used to store
442 <a name="method30"></a>
443 <p/><strong>double Particle::pAbs() </strong> <br/>
445 <strong>double Particle::pAbs2() </strong> <br/>
446 (squared) three-momentum size.
449 <a name="method31"></a>
450 <p/><strong>double Particle::eT() </strong> <br/>
452 <strong>double Particle::eT2() </strong> <br/>
453 (squared) transverse energy,
454 <i>eT = e * sin(theta) = e * pT / pAbs</i>.
457 <a name="method32"></a>
458 <p/><strong>double Particle::theta() </strong> <br/>
460 <strong>double Particle::phi() </strong> <br/>
461 polar and azimuthal angle.
464 <a name="method33"></a>
465 <p/><strong>double Particle::thetaXZ() </strong> <br/>
466 angle in the <i>(p_x, p_z)</i> plane, between <i>-pi</i> and
467 <i>+pi</i>, with 0 along the <i>+z</i> axis
470 <a name="method34"></a>
471 <p/><strong>double Particle::pPos() </strong> <br/>
473 <strong>double Particle::pNeg() </strong> <br/>
477 <a name="method35"></a>
478 <p/><strong>double Particle::y() </strong> <br/>
480 <strong>double Particle::eta() </strong> <br/>
481 rapidity and pseudorapidity.
484 <a name="method36"></a>
485 <p/><strong>double Particle::xDec() </strong> <br/>
487 <strong>double Particle::yDec() </strong> <br/>
489 <strong>double Particle::zDec() </strong> <br/>
491 <strong>double Particle::tDec() </strong> <br/>
492 the decay vertex coordinates, in mm or mm/c. This decay vertex is
493 calculated from the production vertex, the proper lifetime and the
494 four-momentum assuming no magnetic field or other detector interference.
495 It can be used to decide whether a decay should be performed or not,
496 and thus is defined also for particles which PYTHIA did not let decay.
500 Each Particle contains a pointer to the respective
501 <code>ParticleDataEntry</code> object in the
502 <?php $filepath = $_GET["filepath"];
503 echo "<a href='ParticleDataScheme.php?filepath=".$filepath."' target='page'>";?>particle data tables</a>.
504 This gives access to properties of the particle species as such. It is
505 there mainly for convenience, and should be thrown if an event is
506 written to disk, to avoid any problems of object persistency. Should
507 an event later be read back in, the pointer will be recreated from the
508 <code>id</code> code if the normal input methods are used. (Use the
509 <code><?php $filepath = $_GET["filepath"];
510 echo "<a href='EventRecord.php?filepath=".$filepath."' target='page'>";?>Event::restorePtrs()</a></code> method
511 if your persistency scheme bypasses the normal methods.) This pointer is
512 used by the following member functions:
514 <a name="method37"></a>
515 <p/><strong>string Particle::name() </strong> <br/>
516 the name of the particle.
519 <a name="method38"></a>
520 <p/><strong>string Particle::nameWithStatus() </strong> <br/>
521 as above, but for negative-status particles the name is given in
522 brackets to emphasize that they are intermediaries.
525 <a name="method39"></a>
526 <p/><strong>int Particle::spinType() </strong> <br/>
527 <i>2 *spin + 1</i> when defined, else 0.
530 <a name="method40"></a>
531 <p/><strong>double Particle::charge() </strong> <br/>
533 <strong>int Particle::chargeType() </strong> <br/>
534 charge, and three times it to make an integer.
537 <a name="method41"></a>
538 <p/><strong>bool Particle::isCharged() </strong> <br/>
540 <strong>bool Particle::isNeutral() </strong> <br/>
541 charge different from or equal to 0.
544 <a name="method42"></a>
545 <p/><strong>int Particle::colType() </strong> <br/>
546 0 for colour singlets, 1 for triplets,
547 -1 for antitriplets and 2 for octets.
550 <a name="method43"></a>
551 <p/><strong>double Particle::m0() </strong> <br/>
552 the nominal mass of the particle, according to the data tables.
555 <a name="method44"></a>
556 <p/><strong>double Particle::mWidth() </strong> <br/>
558 <strong>double Particle::mMin() </strong> <br/>
560 <strong>double Particle::mMax() </strong> <br/>
561 the width of the particle, and the minimum and maximum allowed mass value
562 for particles with a width, according to the data tables.
565 <a name="method45"></a>
566 <p/><strong>double Particle::mass() </strong> <br/>
567 the mass of the particle, picked according to a Breit-Wigner
568 distribution for particles with width. It is different each time called,
569 and is therefore only used once per particle to set its mass
573 <a name="method46"></a>
574 <p/><strong>double Particle::constituentMass() </strong> <br/>
575 will give the constituent masses for quarks and diquarks,
576 else the same masses as with <code>m0()</code>.
579 <a name="method47"></a>
580 <p/><strong>double Particle::tau0() </strong> <br/>
581 the nominal lifetime <i>tau_0 > 0</i>, in mm/c, of the particle species.
582 It is used to assign the actual lifetime <i>tau</i>.
585 <a name="method48"></a>
586 <p/><strong>bool Particle::mayDecay() </strong> <br/>
587 flag whether particle has been declared unstable or not, offering
588 the main user switch to select which particle species to decay.
591 <a name="method49"></a>
592 <p/><strong>bool Particle::canDecay() </strong> <br/>
593 flag whether decay modes have been declared for a particle,
594 so that it could be decayed, should that be requested.
597 <a name="method50"></a>
598 <p/><strong>bool Particle::doExternalDecay() </strong> <br/>
599 particles that are decayed by an external program.
602 <a name="method51"></a>
603 <p/><strong>bool Particle::isResonance() </strong> <br/>
604 particles where the decay is to be treated as part of the hard process,
605 typically with nominal mass above 20 GeV (<i>W^+-, Z^0, t, ...</i>).
608 <a name="method52"></a>
609 <p/><strong>bool Particle::isVisible() </strong> <br/>
610 particles with strong or electric charge, or composed of ones having it,
611 which thereby should be considered visible in a normal detector.
614 <a name="method53"></a>
615 <p/><strong>bool Particle::isLepton() </strong> <br/>
616 true for a lepton or an antilepton (including neutrinos).
619 <a name="method54"></a>
620 <p/><strong>bool Particle::isQuark() </strong> <br/>
621 true for a quark or an antiquark.
624 <a name="method55"></a>
625 <p/><strong>bool Particle::isGluon() </strong> <br/>
629 <a name="method56"></a>
630 <p/><strong>bool Particle::isHadron() </strong> <br/>
631 true for a hadron (made up out of normal quarks and gluons,
632 i.e. not for R-hadrons and other exotic states).
635 <a name="method57"></a>
636 <p/><strong>ParticleDataEntry& particleDataEntry() </strong> <br/>
637 a reference to the ParticleDataEntry.
641 Not part of the <code>Particle</code> class proper, but obviously tightly
642 linked, are the two methods
644 <a name="method58"></a>
645 <p/><strong>double m(const Particle& pp1, const Particle& pp2) </strong> <br/>
647 <strong>double m2(const Particle& pp1, const Particle& pp2) </strong> <br/>
648 the (squared) invariant mass of two particles.
651 <h3>Methods that perform operations</h3>
653 There are some further methods, some of them inherited from
654 <code>Vec4</code>, to modify the properties of a particle.
655 They are of little interest to the normal user.
657 <a name="method59"></a>
658 <p/><strong>void Particle::rescale3(double fac) </strong> <br/>
659 multiply the three-momentum components by <code>fac</code>.
662 <a name="method60"></a>
663 <p/><strong>void Particle::rescale4(double fac) </strong> <br/>
664 multiply the four-momentum components by <code>fac</code>.
667 <a name="method61"></a>
668 <p/><strong>void Particle::rescale5(double fac) </strong> <br/>
669 multiply the four-momentum components and the mass by <code>fac</code>.
672 <a name="method62"></a>
673 <p/><strong>void Particle::rot(double theta, double phi) </strong> <br/>
674 rotate three-momentum and production vertex by these polar and azimuthal
678 <a name="method63"></a>
679 <p/><strong>void Particle::bst(double betaX, double betaY, double betaZ) </strong> <br/>
680 boost four-momentum and production vertex by this three-vector.
683 <a name="method64"></a>
684 <p/><strong>void Particle::bst(double betaX, double betaY, double betaZ, double gamma) </strong> <br/>
685 as above, but also input the <i>gamma</i> value, to reduce roundoff errors.
688 <a name="method65"></a>
689 <p/><strong>void Particle::bst(const Vec4& pBst) </strong> <br/>
690 boost four-momentum and production vertex by
691 <i>beta = (px/e, py/e, pz/e)</i>.
694 <a name="method66"></a>
695 <p/><strong>void Particle::bst(const Vec4& pBst, double mBst) </strong> <br/>
696 as above, but also use <i>gamma> = e/m</i> to reduce roundoff errors.
699 <a name="method67"></a>
700 <p/><strong>void Particle::bstBack(const Vec4& pBst) </strong> <br/>
702 <strong>void Particle::bstBack(const Vec4& pBst, double mBst) </strong> <br/>
703 as above, but with sign of boost flipped.
706 <a name="method68"></a>
707 <p/><strong>void Particle::rotbst(const RotBstMatrix& M) </strong> <br/>
708 combined rotation and boost of the four-momentum and production vertex.
711 <a name="method69"></a>
712 <p/><strong>void Particle::offsetHistory( int minMother, int addMother, int minDaughter, int addDaughter)) </strong> <br/>
713 add a positive offset to the mother and daughter indices, i.e.
714 if <code>mother1</code> is above <code>minMother</code> then
715 <code>addMother</code> is added to it, same with <code>mother2</code>,
716 if <code>daughter1</code> is above <code>minDaughter</code> then
717 <code>addDaughter</code> is added to it, same with <code>daughter2</code>.
720 <a name="method70"></a>
721 <p/><strong>void Particle::offsetCol( int addCol) </strong> <br/>
722 add a positive offset to colour indices, i.e. if <code>col</code> is
723 positive then <code>addCol</code> is added to it, same with <code>acol</code>.
726 <h3>Constructors and operators</h3>
728 Normally a user would not need to create new particles. However, if
729 necessary, the following constructors and methods may be of interest.
731 <a name="method71"></a>
732 <p/><strong>Particle::Particle() </strong> <br/>
733 constructs an empty particle, i.e. where all properties have been set 0
737 <a name="method72"></a>
738 <p/><strong>Particle::Particle(int id, int status = 0, int mother1 = 0, int mother2 = 0, int daughter1 = 0, int daughter2 = 0, int col = 0, int acol = 0, double px = 0., double py = 0., double pz = 0., double e = 0., double m = 0., double scale = 0.) </strong> <br/>
739 constructs a particle with the input properties provided, and non-provided
743 <a name="method73"></a>
744 <p/><strong>Particle::Particle(int id, int status, int mother1, int mother2, int daughter1, int daughter2, int col, int acol, Vec4 p, double m = 0., double scale = 0.) </strong> <br/>
745 constructs a particle with the input properties provided, and non-provided
749 <a name="method74"></a>
750 <p/><strong>Particle::Particle(const Particle& pt) </strong> <br/>
751 constructs an particle that is a copy of the input one.
754 <a name="method75"></a>
755 <p/><strong>Particle& Particle::operator=(const Particle& pt) </strong> <br/>
756 copies the input particle.
759 <a name="method76"></a>
760 <p/><strong>void Particle::setPDTPtr() </strong> <br/>
761 sets the pointer to the <code>ParticleData</code> objects,
762 i.e. to the full particle data table. Also calls <code>setPDEPtr</code>
766 <a name="method77"></a>
767 <p/><strong>void Particle::setPDEPtr() </strong> <br/>
768 sets the pointer to the <code>ParticleDataEntry</code> object of the
769 particle, based on its current <code>id</code> code.
775 <code><?php $filepath = $_GET["filepath"];
776 echo "<a href='EventRecord.php?filepath=".$filepath."' target='page'>";?>Event</a></code>
777 class also contains a few methods defined for individual particles,
778 but these may require some search in the event record and therefore
779 cannot be defined as <code>Particle</code> methods.
782 Currently there is no information on polarization states.
787 <!-- Copyright (C) 2010 Torbjorn Sjostrand -->