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da0e9ce3 | 1 | //-------------------------------------------------------------------------- |
2 | // | |
3 | // Environment: | |
4 | // This software is part of the EvtGen package developed jointly | |
5 | // for the BaBar and CLEO collaborations. If you use all or part | |
6 | // of it, please give an appropriate acknowledgement. | |
7 | // | |
8 | // Copyright Information: See EvtGen/COPYRIGHT | |
9 | // Copyright (C) 1998 Caltech, UCSB | |
10 | // | |
11 | // Module: EvtDMix.cc | |
12 | // | |
13 | // Description: Routine to decay a particle according th phase space | |
14 | // | |
15 | // Modification history: | |
16 | // | |
17 | // RYD January 8, 1997 Module created | |
18 | // | |
19 | //------------------------------------------------------------------------ | |
20 | // | |
21 | #include "EvtGenBase/EvtPatches.hh" | |
22 | #include <stdlib.h> | |
23 | #include "EvtGenBase/EvtParticle.hh" | |
24 | #include "EvtGenBase/EvtGenKine.hh" | |
25 | #include "EvtGenBase/EvtPDL.hh" | |
26 | #include "EvtGenBase/EvtReport.hh" | |
27 | #include "EvtGenModels/EvtDMix.hh" | |
28 | #include "EvtGenBase/EvtRandom.hh" | |
29 | #include <string> | |
30 | ||
31 | EvtDMix::~EvtDMix() {} | |
32 | ||
33 | std::string EvtDMix::getName(){ | |
34 | ||
35 | return "DMIX"; | |
36 | ||
37 | } | |
38 | ||
39 | EvtDecayBase* EvtDMix::clone(){ | |
40 | ||
41 | return new EvtDMix; | |
42 | ||
43 | } | |
44 | ||
45 | ||
46 | void EvtDMix::init(){ | |
47 | ||
48 | // check that there are 0 arguments | |
49 | checkNArg(3); | |
50 | _rd=getArg(0); | |
51 | _xpr=getArg(1); | |
52 | _ypr=getArg(2); | |
53 | } | |
54 | ||
55 | void EvtDMix::initProbMax(){ | |
56 | ||
57 | noProbMax(); | |
58 | ||
59 | } | |
60 | ||
61 | void EvtDMix::decay( EvtParticle *p ){ | |
62 | ||
63 | //unneeded - lange - may13-02 | |
64 | //if ( p->getNDaug() != 0 ) { | |
65 | //Will end up here because maxrate multiplies by 1.2 | |
66 | // report(DEBUG,"EvtGen") << "In EvtDMix: has " | |
67 | // <<" daugthers should not be here!"<<endl; | |
68 | // return; | |
69 | //} | |
70 | ||
71 | p->initializePhaseSpace(getNDaug(),getDaugs()); | |
72 | ||
73 | double ctau=EvtPDL::getctau(p->getId()); | |
74 | if ( ctau==0. ) return; | |
75 | ||
76 | ||
77 | double pdf, random, gt, weight; | |
78 | ||
79 | double maxPdf=_rd + sqrt(_rd)*_ypr*50. + 2500.0*(_xpr*_xpr+_ypr*_ypr)/4.0; | |
80 | bool keepGoing=true; | |
81 | while ( keepGoing ) { | |
82 | random=EvtRandom::Flat(); | |
83 | gt=-log(random); | |
84 | weight=random; | |
85 | pdf=_rd + sqrt(_rd)*_ypr*gt + gt*gt*(_xpr*_xpr+_ypr*_ypr)/4.0; | |
86 | pdf*=exp(-1.0*gt); | |
87 | pdf/=weight; | |
88 | if ( pdf > maxPdf ) | |
89 | std::cout << pdf << " " << weight << " " << maxPdf << " " << gt << std::endl; | |
90 | if ( pdf > maxPdf*EvtRandom::Flat()) keepGoing=false; | |
91 | } | |
92 | ||
93 | ||
94 | p->setLifetime(gt*ctau); | |
95 | ||
96 | return ; | |
97 | } | |
98 | ||
99 |