bak-BesEvtGen-00-04-08/src/EvtGen/EvtGenModels/EvtVVP.cc

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//--------------------------------------------------------------------------
//
// Environment:
//      This software is part of the EvtGen package developed jointly
//      for the BaBar and CLEO collaborations.  If you use all or part
//      of it, please give an appropriate acknowledgement.
//
// Copyright Information: See EvtGen/COPYRIGHT
//      Copyright (C) 1998      Caltech, UCSB
//
// Module: EvtVVP.cc
//
// Description: The decay Vector -> Vector gamma
//              E.g., CHI1->PSI GAMMA
//
// Modification history:
//
//    RYD       September 5, 1997       Module created
//
//------------------------------------------------------------------------
//
#include "EvtGenBase/EvtPatches.hh"
#include <stdlib.h>
#include <iostream>
#include <string>
#include "EvtGenBase/EvtVector3C.hh"
#include "EvtGenBase/EvtParticle.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtGenKine.hh"
#include "EvtGenBase/EvtVector4C.hh"
#include "EvtGenModels/EvtVVP.hh"
#include "EvtGenBase/EvtReport.hh"
 
EvtVVP::~EvtVVP() {}
 
void EvtVVP::getName(std::string& model_name){
 
  model_name="VVP";
     
}
 
 
EvtDecayBase* EvtVVP::clone(){
 
  return new EvtVVP;
 
}
 
void EvtVVP::init(){
 
  // check that there are 8 arguments
 
  checkNArg(8);  
  checkNDaug(2);
 
  checkSpinParent(EvtSpinType::VECTOR);
  checkSpinDaughter(0,EvtSpinType::VECTOR);
  checkSpinDaughter(1,EvtSpinType::PHOTON);
}
 
void EvtVVP::initProbMax(){
 
  setProbMax(4.0);
 
}
 
void EvtVVP::decay(EvtParticle *p){
 
  p->initializePhaseSpace(getNDaug(),getDaugs());
 
  EvtParticle *v,*ph;
 
  v = p->getDaug(0);
  ph = p->getDaug(1);
 
  EvtVector3C epsp[3];
  EvtVector3C epsv[3];
  EvtVector3C epsph[2];
 
  epsp[0]=p->eps(0).vec();
  epsp[1]=p->eps(1).vec();
  epsp[2]=p->eps(2).vec();
 
  epsv[0]=v->eps(0).vec().conj();
  epsv[1]=v->eps(1).vec().conj();
  epsv[2]=v->eps(2).vec().conj();
 
  epsph[0]=ph->epsParentPhoton(0).vec().conj();
  epsph[1]=ph->epsParentPhoton(1).vec().conj();
 
  int i,j,k;
  for(i=0;i<3;i++){
    for(j=0;j<3;j++){
      for(k=0;k<2;k++){
    vertex(i,j,k,epsp[i].cross(epsv[j])*epsph[k]);
 
      }
    }
  }
 
  return;
 
}