EvtSemiLeptonicBaryonAmp.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: EvtSemiLeptonicBaryonAmp.cc
//
// Description: Routine to implement semileptonic decays to vector
//              mesons.
//
// Modification history:
//
//    Lange    Oct 20, 2004   Module created.
//
//------------------------------------------------------------------------
//
#include "EvtSemiLeptonicBaryonAmp.hh"
#include "EvtAmp.hh"
#include "EvtDiracSpinor.hh"
#include "EvtGammaMatrix.hh"
#include "EvtGenKine.hh"
#include "EvtId.hh"
#include "EvtPDL.hh"
#include "EvtParticle.hh"
#include "EvtPatches.hh"
#include "EvtReport.hh"
#include "EvtSemiLeptonicFF.hh"
#include "EvtTensor4C.hh"
#include "EvtVector4C.hh"
using std::endl;
 
void EvtSemiLeptonicBaryonAmp::CalcAmp( EvtParticle* parent, EvtAmp& amp,
                                        EvtSemiLeptonicFF* FormFactors ) {
 
  static EvtId EM   = EvtPDL::getId( "e-" );
  static EvtId MUM  = EvtPDL::getId( "mu-" );
  static EvtId TAUM = EvtPDL::getId( "tau-" );
  static EvtId EP   = EvtPDL::getId( "e+" );
  static EvtId MUP  = EvtPDL::getId( "mu+" );
  static EvtId TAUP = EvtPDL::getId( "tau+" );
 
  // Add the lepton and neutrino 4 momenta to find q2
 
  EvtVector4R q  = parent->getDaug( 1 )->getP4() + parent->getDaug( 2 )->getP4();
  double      q2 = ( q.mass2() );
 
  double f1v, f1a, f2v, f2a;
  double m_meson = parent->getDaug( 0 )->mass();
 
  FormFactors->getbaryonff( parent->getId(), parent->getDaug( 0 )->getId(), q2, m_meson, &f1v,
                            &f1a, &f2v, &f2a );
 
  EvtVector4R p4b;
  p4b.set( parent->mass(), 0.0, 0.0, 0.0 );
 
  EvtVector4C temp_00_term1;
  EvtVector4C temp_00_term2;
 
  EvtVector4C temp_01_term1;
  EvtVector4C temp_01_term2;
 
  EvtVector4C temp_10_term1;
  EvtVector4C temp_10_term2;
 
  EvtVector4C temp_11_term1;
  EvtVector4C temp_11_term2;
 
  EvtDiracSpinor p0 = parent->sp( 0 );
  EvtDiracSpinor p1 = parent->sp( 1 );
 
  EvtDiracSpinor d0 = parent->getDaug( 0 )->spParent( 0 );
  EvtDiracSpinor d1 = parent->getDaug( 0 )->spParent( 1 );
 
  temp_00_term1.set( 0, f1v * ( d0 * ( EvtGammaMatrix::g0() * p0 ) ) );
  temp_00_term2.set( 0,
                     f1a * ( d0 * ( ( EvtGammaMatrix::g0() * EvtGammaMatrix::g5() ) * p0 ) ) );
  temp_01_term1.set( 0, f1v * ( d0 * ( EvtGammaMatrix::g0() * p1 ) ) );
  temp_01_term2.set( 0,
                     f1a * ( d0 * ( ( EvtGammaMatrix::g0() * EvtGammaMatrix::g5() ) * p1 ) ) );
  temp_10_term1.set( 0, f1v * ( d1 * ( EvtGammaMatrix::g0() * p0 ) ) );
  temp_10_term2.set( 0,
                     f1a * ( d1 * ( ( EvtGammaMatrix::g0() * EvtGammaMatrix::g5() ) * p0 ) ) );
  temp_11_term1.set( 0, f1v * ( d1 * ( EvtGammaMatrix::g0() * p1 ) ) );
  temp_11_term2.set( 0,
                     f1a * ( d1 * ( ( EvtGammaMatrix::g0() * EvtGammaMatrix::g5() ) * p1 ) ) );
 
  temp_00_term1.set( 1, f1v * ( d0 * ( EvtGammaMatrix::g1() * p0 ) ) );
  temp_00_term2.set( 1,
                     f1a * ( d0 * ( ( EvtGammaMatrix::g1() * EvtGammaMatrix::g5() ) * p0 ) ) );
  temp_01_term1.set( 1, f1v * ( d0 * ( EvtGammaMatrix::g1() * p1 ) ) );
  temp_01_term2.set( 1,
                     f1a * ( d0 * ( ( EvtGammaMatrix::g1() * EvtGammaMatrix::g5() ) * p1 ) ) );
  temp_10_term1.set( 1, f1v * ( d1 * ( EvtGammaMatrix::g1() * p0 ) ) );
  temp_10_term2.set( 1,
                     f1a * ( d1 * ( ( EvtGammaMatrix::g1() * EvtGammaMatrix::g5() ) * p0 ) ) );
  temp_11_term1.set( 1, f1v * ( d1 * ( EvtGammaMatrix::g1() * p1 ) ) );
  temp_11_term2.set( 1,
                     f1a * ( d1 * ( ( EvtGammaMatrix::g1() * EvtGammaMatrix::g5() ) * p1 ) ) );
 
  temp_00_term1.set( 2, f1v * ( d0 * ( EvtGammaMatrix::g2() * p0 ) ) );
  temp_00_term2.set( 2,
                     f1a * ( d0 * ( ( EvtGammaMatrix::g2() * EvtGammaMatrix::g5() ) * p0 ) ) );
  temp_01_term1.set( 2, f1v * ( d0 * ( EvtGammaMatrix::g2() * p1 ) ) );
  temp_01_term2.set( 2,
                     f1a * ( d0 * ( ( EvtGammaMatrix::g2() * EvtGammaMatrix::g5() ) * p1 ) ) );
  temp_10_term1.set( 2, f1v * ( d1 * ( EvtGammaMatrix::g2() * p0 ) ) );
  temp_10_term2.set( 2,
                     f1a * ( d1 * ( ( EvtGammaMatrix::g2() * EvtGammaMatrix::g5() ) * p0 ) ) );
  temp_11_term1.set( 2, f1v * ( d1 * ( EvtGammaMatrix::g2() * p1 ) ) );
  temp_11_term2.set( 2,
                     f1a * ( d1 * ( ( EvtGammaMatrix::g2() * EvtGammaMatrix::g5() ) * p1 ) ) );
 
  temp_00_term1.set( 3, f1v * ( d0 * ( EvtGammaMatrix::g3() * p0 ) ) );
  temp_00_term2.set( 3,
                     f1a * ( d0 * ( ( EvtGammaMatrix::g3() * EvtGammaMatrix::g5() ) * p0 ) ) );
  temp_01_term1.set( 3, f1v * ( d0 * ( EvtGammaMatrix::g3() * p1 ) ) );
  temp_01_term2.set( 3,
                     f1a * ( d0 * ( ( EvtGammaMatrix::g3() * EvtGammaMatrix::g5() ) * p1 ) ) );
  temp_10_term1.set( 3, f1v * ( d1 * ( EvtGammaMatrix::g3() * p0 ) ) );
  temp_10_term2.set( 3,
                     f1a * ( d1 * ( ( EvtGammaMatrix::g3() * EvtGammaMatrix::g5() ) * p0 ) ) );
  temp_11_term1.set( 3, f1v * ( d1 * ( EvtGammaMatrix::g3() * p1 ) ) );
  temp_11_term2.set( 3,
                     f1a * ( d1 * ( ( EvtGammaMatrix::g3() * EvtGammaMatrix::g5() ) * p1 ) ) );
 
  EvtVector4C l1, l2;
 
  EvtId l_num = parent->getDaug( 1 )->getId();
  if ( l_num == EM || l_num == MUM || l_num == TAUM )
  {
 
    l1 = EvtLeptonVACurrent( parent->getDaug( 1 )->spParent( 0 ),
                             parent->getDaug( 2 )->spParentNeutrino() );
    l2 = EvtLeptonVACurrent( parent->getDaug( 1 )->spParent( 1 ),
                             parent->getDaug( 2 )->spParentNeutrino() );
  }
  else
  {
    if ( l_num == EP || l_num == MUP || l_num == TAUP )
    {
      l1 = EvtLeptonVACurrent( parent->getDaug( 2 )->spParentNeutrino(),
                               parent->getDaug( 1 )->spParent( 0 ) );
      l2 = EvtLeptonVACurrent( parent->getDaug( 2 )->spParentNeutrino(),
                               parent->getDaug( 1 )->spParent( 1 ) );
    }
    else { report( ERROR, "EvtGen" ) << "Wrong lepton number" << endl; }
  }
 
  amp.vertex( 0, 0, 0, l1.cont( temp_00_term1 + temp_00_term2 ) );
  amp.vertex( 0, 0, 1, l2.cont( temp_00_term1 + temp_00_term2 ) );
 
  amp.vertex( 0, 1, 0, l1.cont( temp_01_term1 + temp_01_term2 ) );
  amp.vertex( 0, 1, 1, l2.cont( temp_01_term1 + temp_01_term2 ) );
 
  amp.vertex( 1, 0, 0, l1.cont( temp_10_term1 + temp_10_term2 ) );
  amp.vertex( 1, 0, 1, l2.cont( temp_10_term1 + temp_10_term2 ) );
 
  amp.vertex( 1, 1, 0, l1.cont( temp_11_term1 + temp_11_term2 ) );
  amp.vertex( 1, 1, 1, l2.cont( temp_11_term1 + temp_11_term2 ) );
 
  return;
}