EvtbTosllVectorAmp.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) 2000      Caltech, UCSB
//
// Module: EvtbTosllVectorAmp.cc
//
// Description: Routine to implement bTosll decays to vector
//              mesons.
//
// Modification history:
//
//    Ryd       January 5,2000       Module created
//
//------------------------------------------------------------------------
//
#include "EvtbTosllVectorAmp.hh"
#include "../EvtGenBase/EvtAmp.hh"
#include "../EvtGenBase/EvtDiracSpinor.hh"
#include "../EvtGenBase/EvtGenKine.hh"
#include "../EvtGenBase/EvtId.hh"
#include "../EvtGenBase/EvtIdSet.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 "EvtbTosllAmp.hh"
#include "EvtbTosllFF.hh"
 
void EvtbTosllVectorAmp::CalcAmp( EvtParticle* parent, EvtAmp& amp,
                                  EvtbTosllFF* formFactors ) {
 
  // 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 a1, a2, a0, v, t1, t2, t3;
  double mesonmass  = parent->getDaug( 0 )->mass();
  double parentmass = parent->mass();
 
  formFactors->getVectorFF( parent->getId(), parent->getDaug( 0 )->getId(), q2, mesonmass, a1,
                            a2, a0, v, t1, t2, t3 );
 
  EvtId daught = parent->getDaug( 0 )->getId();
  bool  btod   = false;
  bool  nnlo   = true;
  if ( daught == EvtPDL::getId( std::string( "rho+" ) ) ||
       daught == EvtPDL::getId( std::string( "rho-" ) ) ||
       daught == EvtPDL::getId( std::string( "rho0" ) ) ||
       daught == EvtPDL::getId( std::string( "omega" ) ) )
    btod = true;
 
  EvtVector4R p4b;
  p4b.set( parent->mass(), 0.0, 0.0, 0.0 );
  EvtVector4R p4meson = parent->getDaug( 0 )->getP4();
 
  EvtVector4C l11, l12;
  EvtVector4C l21, l22;
 
  EvtVector4C a11, a12;
  EvtVector4C a21, a22;
 
  EvtId parentID = parent->getId();
 
  // EvtId l_num = parent->getDaug(1)->getId();
 
  EvtVector4R pbhat     = p4b / parentmass;
  EvtVector4R qhat      = q / parentmass;
  EvtVector4R pkstarhat = p4meson / parentmass;
  EvtVector4R phat      = pbhat + pkstarhat;
 
  EvtComplex c7eff  = EvtbTosllAmp::GetC7Eff( q2, nnlo );
  EvtComplex c9eff  = EvtbTosllAmp::GetC9Eff( q2, nnlo, btod );
  EvtComplex c10eff = EvtbTosllAmp::GetC10Eff( q2, nnlo );
  EvtComplex uniti( 0.0, 1.0 );
 
  double mhatb     = 4.4 / ( parentmass );
  double mhatkstar = mesonmass / ( parentmass );
  double shat      = q2 / ( parentmass * parentmass );
 
  EvtComplex a;
  a = c9eff * v * 2 / ( 1 + mhatkstar ) + 4 * mhatb * c7eff * t1 / shat;
  EvtComplex b;
  b = ( 1 + mhatkstar ) * ( c9eff * a1 + 2 * mhatb * ( 1 - mhatkstar ) * c7eff * t2 / shat );
  EvtComplex c;
  c = ( ( 1 - mhatkstar ) * c9eff * a2 +
        2 * mhatb * c7eff * ( t3 + ( 1 - mhatkstar * mhatkstar ) * t2 / shat ) ) /
      ( 1 - mhatkstar * mhatkstar );
  EvtComplex d;
  d = ( c9eff * ( ( 1 + mhatkstar ) * a1 - ( 1 - mhatkstar ) * a2 - 2 * mhatkstar * a0 ) -
        2 * mhatb * c7eff * t3 ) /
      shat;
  EvtComplex e;
  e = 2 * c10eff * v / ( 1 + mhatkstar );
  EvtComplex f;
  f = ( 1 + mhatkstar ) * c10eff * a1;
  EvtComplex g;
  g = c10eff * a2 / ( 1 + mhatkstar );
  EvtComplex h;
  h = c10eff * ( ( 1 + mhatkstar ) * a1 - ( 1 - mhatkstar ) * a2 - 2 * mhatkstar * a0 ) / shat;
 
  EvtTensor4C T1, T2;
 
  static EvtIdSet bmesons( "B-", "anti-B0" );
  static EvtIdSet bbarmesons( "B+", "B0" );
 
  EvtParticle* lepPlus( 0 );
  EvtParticle* lepMinus( 0 );
 
  int charge1 = EvtPDL::chg3( parent->getDaug( 1 )->getId() );
  int charge2 = EvtPDL::chg3( parent->getDaug( 2 )->getId() );
 
  lepPlus  = ( charge1 > charge2 ) ? parent->getDaug( 1 ) : parent->getDaug( 2 );
  lepMinus = ( charge1 < charge2 ) ? parent->getDaug( 1 ) : parent->getDaug( 2 );
 
  //  static EvtIdSet leptons("e-","mu-","tau-");
  //  static EvtIdSet antileptons("e+","mu+","tau+");
 
  //  if (leptons.contains(l_num)){
  if ( bmesons.contains( parentID ) )
  {
 
    T1 = a * dual( directProd( pbhat, pkstarhat ) ) - b * uniti * EvtTensor4C::g() +
         c * uniti * directProd( pbhat, phat ) + d * uniti * directProd( pbhat, qhat );
 
    T2 = e * dual( directProd( pbhat, pkstarhat ) ) - f * uniti * EvtTensor4C::g() +
         g * uniti * directProd( pbhat, phat ) + h * uniti * directProd( pbhat, qhat );
 
    l11 = EvtLeptonVCurrent( lepPlus->spParent( 0 ), lepMinus->spParent( 0 ) );
    l21 = EvtLeptonVCurrent( lepPlus->spParent( 1 ), lepMinus->spParent( 0 ) );
    l12 = EvtLeptonVCurrent( lepPlus->spParent( 0 ), lepMinus->spParent( 1 ) );
    l22 = EvtLeptonVCurrent( lepPlus->spParent( 1 ), lepMinus->spParent( 1 ) );
 
    a11 = EvtLeptonACurrent( lepPlus->spParent( 0 ), lepMinus->spParent( 0 ) );
    a21 = EvtLeptonACurrent( lepPlus->spParent( 1 ), lepMinus->spParent( 0 ) );
    a12 = EvtLeptonACurrent( lepPlus->spParent( 0 ), lepMinus->spParent( 1 ) );
    a22 = EvtLeptonACurrent( lepPlus->spParent( 1 ), lepMinus->spParent( 1 ) );
  }
  else
  {
 
    if ( bbarmesons.contains( parentID ) )
    {
 
      T1 = -a * dual( directProd( pbhat, pkstarhat ) ) - b * uniti * EvtTensor4C::g() +
           c * uniti * directProd( pbhat, phat ) + d * uniti * directProd( pbhat, qhat );
 
      T2 = -e * dual( directProd( pbhat, pkstarhat ) ) - f * uniti * EvtTensor4C::g() +
           g * uniti * directProd( pbhat, phat ) + h * uniti * directProd( pbhat, qhat );
 
      l11 = EvtLeptonVCurrent( lepPlus->spParent( 1 ), lepMinus->spParent( 1 ) );
      l21 = EvtLeptonVCurrent( lepPlus->spParent( 0 ), lepMinus->spParent( 1 ) );
      l12 = EvtLeptonVCurrent( lepPlus->spParent( 1 ), lepMinus->spParent( 0 ) );
      l22 = EvtLeptonVCurrent( lepPlus->spParent( 0 ), lepMinus->spParent( 0 ) );
 
      a11 = EvtLeptonACurrent( lepPlus->spParent( 1 ), lepMinus->spParent( 1 ) );
      a21 = EvtLeptonACurrent( lepPlus->spParent( 0 ), lepMinus->spParent( 1 ) );
      a12 = EvtLeptonACurrent( lepPlus->spParent( 1 ), lepMinus->spParent( 0 ) );
      a22 = EvtLeptonACurrent( lepPlus->spParent( 0 ), lepMinus->spParent( 0 ) );
    }
    else { report( ERROR, "EvtGen" ) << "Wrong lepton number\n"; }
  }
 
  int i;
 
  for ( i = 0; i < 3; i++ )
  {
    EvtVector4C eps = parent->getDaug( 0 )->epsParent( i ).conj();
 
    EvtVector4C E1 = T1.cont1( eps );
    EvtVector4C E2 = T2.cont1( eps );
 
    amp.vertex( i, 0, 0, l11 * E1 + a11 * E2 );
    amp.vertex( i, 0, 1, l12 * E1 + a12 * E2 );
    amp.vertex( i, 1, 0, l21 * E1 + a21 * E2 );
    amp.vertex( i, 1, 1, l22 * E1 + a22 * E2 );
  }
}