1 //--------------------------------------------------------------------------
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.
8 // Copyright Information: See EvtGen/COPYRIGHT
9 // Copyright (C) 1998 Caltech, UCSB
11 // Module: EvtSVVHelAmp.cc
13 // Description: Routine to decay scalar -> 2 vectors
14 // by specifying the helicity amplitudes
16 // Modification history:
18 // RYD November 24, 1996 Module created
20 //------------------------------------------------------------------------
22 #include "EvtGenBase/EvtPatches.hh"
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/EvtVector3C.hh"
30 #include "EvtGenBase/EvtVector3R.hh"
31 #include "EvtGenBase/EvtTensor3C.hh"
32 #include "EvtGenBase/EvtReport.hh"
33 #include "EvtGenModels/EvtSVVHelAmp.hh"
34 #include "EvtGenBase/EvtId.hh"
37 EvtSVVHelAmp::~EvtSVVHelAmp() {}
39 std::string EvtSVVHelAmp::getName(){
46 EvtDecayBase* EvtSVVHelAmp::clone(){
48 return new EvtSVVHelAmp;
52 void EvtSVVHelAmp::init(){
54 // check that there are 6 arguments
58 checkSpinParent(EvtSpinType::SCALAR);
60 checkSpinDaughter(0,EvtSpinType::VECTOR);
61 checkSpinDaughter(1,EvtSpinType::VECTOR);
66 void EvtSVVHelAmp::initProbMax(){
68 setProbMax(getArg(0)*getArg(0)+getArg(2)*getArg(2)+getArg(4)*getArg(4));
73 void EvtSVVHelAmp::decay( EvtParticle *p){
75 SVVHel(p,_amp2,getDaug(0),getDaug(1),
76 EvtComplex(getArg(0)*cos(getArg(1)),getArg(0)*sin(getArg(1))),
77 EvtComplex(getArg(2)*cos(getArg(3)),getArg(2)*sin(getArg(3))),
78 EvtComplex(getArg(4)*cos(getArg(5)),getArg(4)*sin(getArg(5))));
85 void EvtSVVHelAmp::SVVHel(EvtParticle *parent,EvtAmp& amp,EvtId n_v1,EvtId n_v2,
86 const EvtComplex& hp,const EvtComplex& h0,
87 const EvtComplex& hm){
89 // Routine to decay a vector into a vector and scalar. Started
90 // by ryd on Oct 17, 1996.
98 parent->initializePhaseSpace(tndaug,tdaug);
101 v1 = parent->getDaug(0);
102 v2 = parent->getDaug(1);
104 EvtVector4R momv1 = v1->getP4();
105 //EvtVector4R momv2 = v2->getP4();
107 EvtVector3R v1dir(momv1.get(1),momv1.get(2),momv1.get(3));
108 v1dir=v1dir/v1dir.d3mag();
110 EvtComplex a=-0.5*(hp+hm);
111 EvtComplex b=EvtComplex(0.0,0.5)*(hp-hm);
112 EvtComplex c=h0+0.5*(hp+hm);
114 EvtTensor3C M=a*EvtTensor3C::id()+
116 c*directProd(v1dir,v1dir);
118 EvtVector3C t0=M.cont1(v1->eps(0).vec().conj());
119 EvtVector3C t1=M.cont1(v1->eps(1).vec().conj());
120 EvtVector3C t2=M.cont1(v1->eps(2).vec().conj());
122 EvtVector3C eps0=v2->eps(0).vec().conj();
123 EvtVector3C eps1=v2->eps(1).vec().conj();
124 EvtVector3C eps2=v2->eps(2).vec().conj();
126 amp.vertex(0,0,t0*eps0);
127 amp.vertex(0,1,t0*eps1);
128 amp.vertex(0,2,t0*eps2);
130 amp.vertex(1,0,t1*eps0);
131 amp.vertex(1,1,t1*eps1);
132 amp.vertex(1,2,t1*eps2);
134 amp.vertex(2,0,t2*eps0);
135 amp.vertex(2,1,t2*eps1);
136 amp.vertex(2,2,t2*eps2);