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: EvtSVPHelAmp.cc
13 // Description: Routine to decay scalar -> vectors+photon
14 // by specifying the helicity amplitudes
16 // Modification history:
18 // RYD July 26, 1997 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/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"
35 EvtSVPHelAmp::~EvtSVPHelAmp() {}
37 std::string EvtSVPHelAmp::getName(){
44 EvtDecayBase* EvtSVPHelAmp::clone(){
46 return new EvtSVPHelAmp;
50 void EvtSVPHelAmp::initProbMax(){
52 setProbMax(getArg(0)*getArg(0)+getArg(2)*getArg(2));
57 void EvtSVPHelAmp::init(){
59 // check that there are 4 arguments
63 checkSpinParent(EvtSpinType::SCALAR);
65 checkSpinDaughter(0,EvtSpinType::VECTOR);
66 checkSpinDaughter(1,EvtSpinType::PHOTON);
70 void EvtSVPHelAmp::decay( EvtParticle *p ){
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)));
76 // Routine to decay a vector into a vector and scalar. Started
77 // by ryd on Oct 17, 1996.
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);
87 p->initializePhaseSpace(getNDaug(),getDaugs());
90 EvtVector4R momv1 = v1->getP4();
91 EvtVector4R momph = ph->getP4();
95 g.setdiag(1.0,-1.0,-1.0,-1.0);
99 v=momv1/momv1.d3mag();
100 vp=(momv1+momph)/(momv1+momph).mass();
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);
106 EvtVector4C ep0,ep1,ep2;
108 ep0=d.cont1(v1->eps(0).conj());
109 ep1=d.cont1(v1->eps(1).conj());
110 ep2=d.cont1(v1->eps(2).conj());
112 EvtVector4C ep20,ep21,ep22;
114 ep20=ph->epsParentPhoton(0).conj();
115 ep21=ph->epsParentPhoton(1).conj();
117 vertex(0,0,ep0*ep20);
118 vertex(0,1,ep0*ep21);
120 vertex(1,0,ep1*ep20);
121 vertex(1,1,ep1*ep21);
123 vertex(2,0,ep2*ep20);
124 vertex(2,1,ep2*ep21);