EvtVSPPwave.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: EvtVSPPwave.cc
//
// Description: Routine to decay vector-> scalar photon in P-wave
//
// Modification history:
//
//    RYD       November 24, 1996       Module created
//
//------------------------------------------------------------------------
//
#include "EvtVSPPwave.hh"
#include "../EvtGenBase/EvtGenKine.hh"
#include "../EvtGenBase/EvtPDL.hh"
#include "../EvtGenBase/EvtParticle.hh"
#include "../EvtGenBase/EvtPatches.hh"
#include "../EvtGenBase/EvtReport.hh"
#include "../EvtGenBase/EvtTensor4C.hh"
#include "../EvtGenBase/EvtVector4C.hh"
#include <stdlib.h>
#include <string>
 
EvtVSPPwave::~EvtVSPPwave() {}
 
void EvtVSPPwave::getName( std::string& model_name ) { model_name = "VSP_PWAVE"; }
 
EvtDecayBase* EvtVSPPwave::clone() { return new EvtVSPPwave; }
 
void EvtVSPPwave::init() {
 
  // check that there are 0 arguments
  checkNArg( 0 );
  checkNDaug( 2 );
 
  checkSpinParent( EvtSpinType::VECTOR );
 
  checkSpinDaughter( 0, EvtSpinType::SCALAR );
  checkSpinDaughter( 1, EvtSpinType::PHOTON );
}
 
void EvtVSPPwave::initProbMax() { setProbMax( 1 ); }
 
void EvtVSPPwave::decay( EvtParticle* p ) {
 
  p->initializePhaseSpace( getNDaug(), getDaugs() );
 
  EvtParticle* gamma;
  gamma = p->getDaug( 1 );
 
  double      m_p      = p->mass();
  EvtVector4R momgamma = gamma->getP4();
 
  // work in the parent ,p,  rest frame.
  EvtVector4R p4_p;
  p4_p.set( m_p, 0.0, 0.0, 0.0 );
 
  //  Put phase space results into the daughters.
 
  EvtTensor4C tds;
 
  double norm = 1 / ( m_p * momgamma.d3mag() );
 
  tds = dual( directProd( norm * p4_p, momgamma ) );
 
  vertex( 0, 0, ( tds.cont1( p->eps( 0 ) ) ).cont( gamma->epsParentPhoton( 0 ).conj() ) );
  vertex( 0, 1, ( tds.cont1( p->eps( 0 ) ) ).cont( gamma->epsParentPhoton( 1 ).conj() ) );
 
  vertex( 1, 0, ( tds.cont1( p->eps( 1 ) ) ).cont( gamma->epsParentPhoton( 0 ).conj() ) );
  vertex( 1, 1, ( tds.cont1( p->eps( 1 ) ) ).cont( gamma->epsParentPhoton( 1 ).conj() ) );
 
  vertex( 2, 0, ( tds.cont1( p->eps( 2 ) ) ).cont( gamma->epsParentPhoton( 0 ).conj() ) );
  vertex( 2, 1, ( tds.cont1( p->eps( 2 ) ) ).cont( gamma->epsParentPhoton( 1 ).conj() ) );
 
  return;
}