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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: EvtVVSPwave.cc | |
12 | // | |
13 | // Description: Routine to decay vector-> vector pi pi where the | |
14 | // decay is S-wave dominated. | |
15 | // | |
16 | // Modification history: | |
17 | // | |
18 | // RYD December 11, 1999 Module created | |
19 | // | |
20 | //------------------------------------------------------------------------ | |
21 | // | |
22 | #include "EvtGenBase/EvtPatches.hh" | |
23 | #include <stdlib.h> | |
24 | #include "EvtGenBase/EvtParticle.hh" | |
25 | #include "EvtGenBase/EvtGenKine.hh" | |
26 | #include "EvtGenBase/EvtPDL.hh" | |
27 | #include "EvtGenBase/EvtVector4C.hh" | |
28 | #include "EvtGenBase/EvtTensor4C.hh" | |
29 | #include "EvtGenBase/EvtReport.hh" | |
30 | #include "EvtGenModels/EvtVVpipi.hh" | |
31 | #include <string> | |
32 | using std::endl; | |
33 | ||
34 | EvtVVpipi::~EvtVVpipi() {} | |
35 | ||
36 | std::string EvtVVpipi::getName(){ | |
37 | ||
38 | return "VVPIPI"; | |
39 | ||
40 | } | |
41 | ||
42 | ||
43 | EvtDecayBase* EvtVVpipi::clone(){ | |
44 | ||
45 | return new EvtVVpipi; | |
46 | ||
47 | } | |
48 | ||
49 | void EvtVVpipi::init(){ | |
50 | ||
51 | static EvtId PIP=EvtPDL::getId("pi+"); | |
52 | static EvtId PIM=EvtPDL::getId("pi-"); | |
53 | static EvtId PI0=EvtPDL::getId("pi0"); | |
54 | ||
55 | // check that there are 0 arguments | |
56 | checkNArg(0); | |
57 | checkNDaug(3); | |
58 | ||
59 | checkSpinParent(EvtSpinType::VECTOR); | |
60 | checkSpinDaughter(0,EvtSpinType::VECTOR); | |
61 | ||
62 | ||
63 | ||
64 | if ((!(getDaug(1)==PIP&&getDaug(2)==PIM))&& | |
65 | (!(getDaug(1)==PI0&&getDaug(2)==PI0))) { | |
66 | report(ERROR,"EvtGen") << "EvtVVpipi generator expected " | |
67 | << " pi+ and pi- (or pi0 and pi0) " | |
68 | << "as 2nd and 3rd daughter. "<<endl; | |
69 | report(ERROR,"EvtGen") << "Will terminate execution!"<<endl; | |
70 | ::abort(); | |
71 | } | |
72 | ||
73 | } | |
74 | ||
75 | void EvtVVpipi::initProbMax() { | |
76 | ||
77 | //Hard coded... should not be hard to calculate... | |
78 | setProbMax(0.08); | |
79 | ||
80 | } | |
81 | ||
82 | void EvtVVpipi::decay( EvtParticle *p){ | |
83 | ||
84 | p->initializePhaseSpace(getNDaug(),getDaugs()); | |
85 | ||
86 | EvtParticle *v,*s1,*s2; | |
87 | ||
88 | v=p->getDaug(0); | |
89 | s1=p->getDaug(1); | |
90 | s2=p->getDaug(2); | |
91 | ||
92 | // Put phase space results into the daughters. | |
93 | ||
94 | EvtVector4C ep0,ep1,ep2; | |
95 | ||
96 | ep0=p->eps(0); | |
97 | ep1=p->eps(1); | |
98 | ep2=p->eps(2); | |
99 | ||
100 | double fac=(s1->getP4()+s2->getP4()).mass2()-4*s1->mass()*s2->mass(); | |
101 | ||
102 | vertex(0,0,fac*(ep0*v->epsParent(0).conj())); | |
103 | vertex(0,1,fac*(ep0*v->epsParent(1).conj())); | |
104 | vertex(0,2,fac*(ep0*v->epsParent(2).conj())); | |
105 | ||
106 | vertex(1,0,fac*(ep1*v->epsParent(0).conj())); | |
107 | vertex(1,1,fac*(ep1*v->epsParent(1).conj())); | |
108 | vertex(1,2,fac*(ep1*v->epsParent(2).conj())); | |
109 | ||
110 | vertex(2,0,fac*(ep2*v->epsParent(0).conj())); | |
111 | vertex(2,1,fac*(ep2*v->epsParent(1).conj())); | |
112 | vertex(2,2,fac*(ep2*v->epsParent(2).conj())); | |
113 | ||
114 | return ; | |
115 | ||
116 | } | |
117 | ||
118 | ||
119 | ||
120 |