EvtSTS.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: EvtSTS.cc
//
// Description: Routine to decay scalar -> tensor scalar.
//
//
// Modification history:
//
//    RYD       Aug  21, 1998       Module created
//
//------------------------------------------------------------------------
//
#include "EvtSTS.hh"
#include "../EvtGenBase/EvtCPUtil.hh"
#include "../EvtGenBase/EvtGenKine.hh"
#include "../EvtGenBase/EvtId.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>
 
EvtSTS::~EvtSTS() {}
 
void EvtSTS::getName( std::string& model_name ) { model_name = "STS"; }
 
EvtDecayBase* EvtSTS::clone() { return new EvtSTS; }
 
void EvtSTS::initProbMax() { setProbMax( 20.0 ); }
 
void EvtSTS::init() {
 
  // check that there are 0 arguments
  checkNArg( 0 );
  checkNDaug( 2 );
 
  checkSpinParent( EvtSpinType::SCALAR );
 
  checkSpinDaughter( 0, EvtSpinType::TENSOR );
  checkSpinDaughter( 1, EvtSpinType::SCALAR );
}
 
void EvtSTS::decay( EvtParticle* p ) {
 
  p->initializePhaseSpace( getNDaug(), getDaugs() );
 
  EvtParticle* t1 = p->getDaug( 0 );
 
  EvtVector4R momt  = t1->getP4();
  EvtVector4R moms  = p->getDaug( 1 )->getP4();
  double      masst = t1->mass();
 
  EvtVector4R p4_parent = momt + moms;
 
  double m_parent = p4_parent.mass();
 
  double norm = masst * masst / ( m_parent * momt.d3mag() * momt.d3mag() );
 
  vertex( 0, norm * t1->epsTensorParent( 0 ).cont1( p4_parent ) * p4_parent );
  vertex( 1, norm * t1->epsTensorParent( 1 ).cont1( p4_parent ) * p4_parent );
  vertex( 2, norm * t1->epsTensorParent( 2 ).cont1( p4_parent ) * p4_parent );
  vertex( 3, norm * t1->epsTensorParent( 3 ).cont1( p4_parent ) * p4_parent );
  vertex( 4, norm * t1->epsTensorParent( 4 ).cont1( p4_parent ) * p4_parent );
 
  return;
}