EvtMassAmp.cc

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//-----------------------------------------------------------------------
// File and Version Information:
//      $Id: EvtMassAmp.cc,v 1.2 2011/01/06 22:57:56 pingrg Exp $
//
// 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:
//      Copyright (C) 1998 Caltech, UCSB
//
// Module creator:
//      Alexei Dvoretskii, Caltech, 2001-2002.
//-----------------------------------------------------------------------
#include "EvtPatches.hh"
 
#include "EvtMassAmp.hh"
 
EvtMassAmp::EvtMassAmp( const EvtPropBreitWignerRel& prop, const EvtTwoBodyVertex& vd )
    : EvtAmplitude<EvtPoint1D>()
    , _prop( prop )
    , _vd( vd )
    , _vb( 0 )
    , _useBirthFact( false )
    , _useDeathFact( false )
    , _useBirthFactFF( false )
    , _useDeathFactFF( false )
    , _fixUpMassForMax( false )
    , _addfactor( 0. ) {}
 
EvtMassAmp::EvtMassAmp( const EvtMassAmp& other )
    : EvtAmplitude<EvtPoint1D>( other )
    , _prop( other._prop )
    , _vd( other._vd )
    , _vb( other._vb ? new EvtTwoBodyVertex( *other._vb ) : 0 )
    , _useBirthFact( other._useBirthFact )
    , _useDeathFact( other._useDeathFact )
    , _useBirthFactFF( other._useBirthFactFF )
    , _useDeathFactFF( other._useDeathFactFF )
    , _fixUpMassForMax( other._fixUpMassForMax )
    , _addfactor( other._addfactor ) {}
 
EvtMassAmp::~EvtMassAmp() {
  if ( _vb ) delete _vb;
}
 
EvtComplex EvtMassAmp::amplitude( const EvtPoint1D& p ) const {
  // Modified vertex
 
  double m = p.value();
  // keep things from crashing..
 
  if ( m < ( _vd.mA() + _vd.mB() ) ) return EvtComplex( 0., 0. );
 
  EvtTwoBodyKine vd( _vd.mA(), _vd.mB(), m );
 
  // Compute mass-dependent width for relativistic propagator
 
  EvtPropBreitWignerRel bw( _prop.m0(), _prop.g0() * _vd.widthFactor( vd ) );
  EvtComplex            amp = bw.evaluate( m );
 
  // Birth vertex factors
 
  if ( _useBirthFact )
  {
 
    assert( _vb );
    if ( ( m + _vb->mB() ) < _vb->mAB() )
    {
      EvtTwoBodyKine vb( m, _vb->mB(), _vb->mAB() );
      double         phsp = _vb->phaseSpaceFactor( vb, EvtTwoBodyKine::AB );
      amp *= phsp;
 
      if ( _fixUpMassForMax ) { amp *= sqrt( ( vb.p() / _vb->pD() ) ); }
      if ( _useBirthFactFF )
      {
 
        assert( _vb );
        amp *= _vb->formFactor( vb );
      }
    }
    else
    {
      if ( _vb->L() != 0 ) amp = 0.;
    }
  }
 
  // Decay vertex factors
 
  if ( _useDeathFact )
  {
    amp *= _vd.phaseSpaceFactor( vd, EvtTwoBodyKine::AB );
    if ( _fixUpMassForMax ) { amp *= sqrt( ( vd.p() / _vd.pD() ) ); }
  }
  if ( _useDeathFactFF ) amp *= _vd.formFactor( vd );
 
  // AddFactorPn
 
  if ( fabs( _addfactor ) > 0.00000001 )
  { // addFactorPn, pingrg-2011-1-6
    assert( _vb );
    double phsp;
    if ( ( m + _vb->mB() ) < _vb->mAB() )
    {
      EvtTwoBodyKine vb( m, _vb->mB(), _vb->mAB() );
      phsp = vb.p( EvtTwoBodyKine::AB );
    }
    else
    {
      if ( _vb->L() != 0 ) phsp = 0.;
    }
 
    amp *= pow( phsp, _addfactor );
    //   std::cout<<"EvtMassAmp::addFactorPn= "<<pow(phsp,_addfactor)<<std::endl;
  }
 
  return amp;
}