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) 2001 Caltech, UCSB
11 // Module: EvtSVSCPLH.cc
13 // Description: The decay of a scalar to a scalar and a vector particle are
14 // performed with CP violation and different widths for
15 // the cp even and odd states. E.g. B->J/psi K_S.
17 // Modification history:
19 // Ryd March 29, 2001 Module created
21 //------------------------------------------------------------------------
23 #include "EvtGenBase/EvtPatches.hh"
25 #include "EvtGenBase/EvtParticle.hh"
26 #include "EvtGenBase/EvtGenKine.hh"
27 #include "EvtGenBase/EvtCPUtil.hh"
28 #include "EvtGenBase/EvtPDL.hh"
29 #include "EvtGenBase/EvtReport.hh"
30 #include "EvtGenModels/EvtSVSCPLH.hh"
31 #include "EvtGenBase/EvtId.hh"
33 #include "EvtGenBase/EvtConst.hh"
34 #include "EvtGenBase/EvtVector4C.hh"
37 EvtSVSCPLH::~EvtSVSCPLH() {}
39 std::string EvtSVSCPLH::getName(){
46 EvtDecayBase* EvtSVSCPLH::clone(){
48 return new EvtSVSCPLH;
52 void EvtSVSCPLH::init(){
54 // check that there are 8 arguments
58 checkSpinParent(EvtSpinType::SCALAR);
60 checkSpinDaughter(0,EvtSpinType::VECTOR);
61 checkSpinDaughter(1,EvtSpinType::SCALAR);
63 static double ctau=EvtPDL::getctau(EvtPDL::getId("B0"));
67 _dgamma=EvtConst::c*getArg(1)/ctau;
69 _qop=getArg(2)*exp(EvtComplex(0.0,getArg(3)));
73 _Af=getArg(4)*exp(EvtComplex(0.0,getArg(5)));
74 _Abarf=getArg(6)*exp(EvtComplex(0.0,getArg(7)));
77 report(INFO,"EvtGen")<<":EvtSVSCPLH:dm="<<_dm<<endl;
78 report(INFO,"EvtGen")<<":EvtSVSCPLH:dGamma="<<_dgamma<<endl;
79 report(INFO,"EvtGen")<<":EvtSVSCPLH:q/p="<<_qop<<endl;
80 report(INFO,"EvtGen")<<":EvtSVSCPLH:Af="<<_Af<<endl;
81 report(INFO,"EvtGen")<<":EvtSVSCPLH:Abarf="<<_Abarf<<endl;
87 void EvtSVSCPLH::initProbMax(){
89 //This is probably not quite right, but it should do as a start...
92 setProbMax(4.0*(getArg(4)*getArg(4)+getArg(6)*getArg(6)));
96 void EvtSVSCPLH::decay( EvtParticle *p){
98 p->initializePhaseSpace(getNDaug(),getDaugs());
100 static EvtId B0=EvtPDL::getId("B0");
101 static EvtId B0B=EvtPDL::getId("anti-B0");
106 EvtCPUtil::OtherB(p,t,other_b,0.5);
108 //convert time from mm to seconds
111 //sign convention is dm=Mheavy-Mlight
112 // dGamma=Gammalight-Gammaheavy
113 //such that in the standard model both of these are positive.
114 EvtComplex gp=0.5*(exp(EvtComplex(0.25*t*_dgamma,-0.5*t*_dm))+exp(EvtComplex(-0.25*t*_dgamma,0.5*t*_dm)));
115 EvtComplex gm=0.5*(exp(EvtComplex(0.25*t*_dgamma,-0.5*t*_dm))-exp(EvtComplex(-0.25*t*_dgamma,0.5*t*_dm)));
120 amp=gp*_Af+_qop*gm*_Abarf;
122 else if (other_b==B0){
123 amp=gp*_Abarf+_poq*gm*_Af;
126 report(ERROR,"EvtGen") << "other_b was not B0 or B0B!"<<endl;
130 EvtVector4R p4_parent=p->getP4Restframe();;
132 double norm=p->getDaug(0)->mass()/(p->getDaug(0)->getP4().d3mag()*p4_parent.mass());
134 EvtParticle* v=p->getDaug(0);
136 vertex(0,amp*norm*(p4_parent*(v->epsParent(0))));
137 vertex(1,amp*norm*(p4_parent*(v->epsParent(1))));
138 vertex(2,amp*norm*(p4_parent*(v->epsParent(2))));