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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: EvtSVPHelAmp.cc | |
12 | // | |
13 | // Description: Routine to decay scalar -> vectors+photon | |
14 | // by specifying the helicity amplitudes | |
15 | // | |
16 | // Modification history: | |
17 | // | |
18 | // RYD July 26, 1997 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/EvtVector4R.hh" | |
28 | #include "EvtGenBase/EvtVector4C.hh" | |
29 | #include "EvtGenBase/EvtTensor4C.hh" | |
30 | #include "EvtGenBase/EvtReport.hh" | |
31 | #include "EvtGenBase/EvtComplex.hh" | |
32 | #include "EvtGenModels/EvtSVPHelAmp.hh" | |
33 | #include <string> | |
34 | ||
35 | EvtSVPHelAmp::~EvtSVPHelAmp() {} | |
36 | ||
37 | std::string EvtSVPHelAmp::getName(){ | |
38 | ||
39 | return "SVP_HELAMP"; | |
40 | ||
41 | } | |
42 | ||
43 | ||
44 | EvtDecayBase* EvtSVPHelAmp::clone(){ | |
45 | ||
46 | return new EvtSVPHelAmp; | |
47 | ||
48 | } | |
49 | ||
50 | void EvtSVPHelAmp::initProbMax(){ | |
51 | ||
52 | setProbMax(getArg(0)*getArg(0)+getArg(2)*getArg(2)); | |
53 | ||
54 | } | |
55 | ||
56 | ||
57 | void EvtSVPHelAmp::init(){ | |
58 | ||
59 | // check that there are 4 arguments | |
60 | checkNArg(4); | |
61 | checkNDaug(2); | |
62 | ||
63 | checkSpinParent(EvtSpinType::SCALAR); | |
64 | ||
65 | checkSpinDaughter(0,EvtSpinType::VECTOR); | |
66 | checkSpinDaughter(1,EvtSpinType::PHOTON); | |
67 | ||
68 | } | |
69 | ||
70 | void EvtSVPHelAmp::decay( EvtParticle *p ){ | |
71 | ||
72 | EvtComplex hp(getArg(0)*cos(getArg(1)),getArg(0)*sin(getArg(1))); | |
73 | EvtComplex hm(getArg(2)*cos(getArg(3)),getArg(2)*sin(getArg(3))); | |
74 | ||
75 | ||
76 | // Routine to decay a vector into a vector and scalar. Started | |
77 | // by ryd on Oct 17, 1996. | |
78 | ||
79 | ||
80 | // This routine is adopted from EvtSVVHel and since there is | |
81 | // a photon that can not have helicity 0 this is put in by | |
82 | // setting the h0 amplitude to 0. | |
83 | EvtComplex h0=EvtComplex(0.0,0.0); | |
84 | ||
85 | EvtParticle *v1,*ph; | |
86 | ||
87 | p->initializePhaseSpace(getNDaug(),getDaugs()); | |
88 | v1 = p->getDaug(0); | |
89 | ph = p->getDaug(1); | |
90 | EvtVector4R momv1 = v1->getP4(); | |
91 | EvtVector4R momph = ph->getP4(); | |
92 | ||
93 | EvtTensor4C d,g; | |
94 | ||
95 | g.setdiag(1.0,-1.0,-1.0,-1.0); | |
96 | ||
97 | EvtVector4R v,vp; | |
98 | ||
99 | v=momv1/momv1.d3mag(); | |
100 | vp=(momv1+momph)/(momv1+momph).mass(); | |
101 | ||
102 | d=((1.0/sqrt(3.0))*(h0-(hp+hm))*(-1.0/sqrt(3.0)))*g+ | |
103 | ((1.0/sqrt(2.0))*(hp-hm)*EvtComplex(0.0,1.0)*(sqrt(1.0/2.0)))*dual(directProd(v,vp))+ | |
104 | (sqrt(2.0/3.0)*(h0+0.5*(hp+hm))*sqrt(3.0/2.0))*(directProd(v,v)+(1.0/3.0)*g); | |
105 | ||
106 | EvtVector4C ep0,ep1,ep2; | |
107 | ||
108 | ep0=d.cont1(v1->eps(0).conj()); | |
109 | ep1=d.cont1(v1->eps(1).conj()); | |
110 | ep2=d.cont1(v1->eps(2).conj()); | |
111 | ||
112 | EvtVector4C ep20,ep21,ep22; | |
113 | ||
114 | ep20=ph->epsParentPhoton(0).conj(); | |
115 | ep21=ph->epsParentPhoton(1).conj(); | |
116 | ||
117 | vertex(0,0,ep0*ep20); | |
118 | vertex(0,1,ep0*ep21); | |
119 | ||
120 | vertex(1,0,ep1*ep20); | |
121 | vertex(1,1,ep1*ep21); | |
122 | ||
123 | vertex(2,0,ep2*ep20); | |
124 | vertex(2,1,ep2*ep21); | |
125 | ||
126 | ||
127 | return ; | |
128 | ||
129 | } | |
130 |