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 "EvtVVP.hh"
#include "../EvtGenBase/EvtGenKine.hh"
#include "../EvtGenBase/EvtPDL.hh"
#include "../EvtGenBase/EvtParticle.hh"
#include "../EvtGenBase/EvtPatches.hh"
#include "../EvtGenBase/EvtReport.hh"
#include "../EvtGenBase/EvtVector3C.hh"
#include "../EvtGenBase/EvtVector4C.hh"
#include <iostream>
#include <stdlib.h>
#include <string>
 
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;
}