EvtbTosllScalarAmp.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: EvtbTosllScalarAmp.cc
//
// Description: Routine to implement bTosll decays to pseudo-scalar
//              mesons.
//
// Modification history:
//
//    Ryd       January 5,2000       Module created
//
//------------------------------------------------------------------------
//
#include "EvtbTosllScalarAmp.hh"
#include "../EvtGenBase/EvtAmp.hh"
#include "../EvtGenBase/EvtConst.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 EvtbTosllScalarAmp::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 fp, f0, ft;
  double mesonmass  = parent->getDaug( 0 )->mass();
  double parentmass = parent->mass();
 
  formFactors->getScalarFF( parent->getId(), parent->getDaug( 0 )->getId(), q2, mesonmass, fp,
                            f0, ft );
 
  EvtId daught = parent->getDaug( 0 )->getId();
  bool  btod   = false;
  bool  nnlo   = true;
  if ( daught == EvtPDL::getId( std::string( "pi+" ) ) ||
       daught == EvtPDL::getId( std::string( "pi-" ) ) ||
       daught == EvtPDL::getId( std::string( "pi0" ) ) ||
       daught == EvtPDL::getId( std::string( "eta" ) ) ||
       daught == EvtPDL::getId( std::string( "eta'" ) ) )
    btod = true;
 
  EvtVector4R p4b;
  p4b.set( parent->mass(), 0.0, 0.0, 0.0 );
 
  EvtVector4C l11, l12;
  EvtVector4C l21, l22;
 
  EvtVector4C a11, a12;
  EvtVector4C a21, a22;
 
  EvtId l_num = parent->getDaug( 1 )->getId();
 
  EvtVector4C T1, T2;
 
  EvtVector4R phat = p4b / parentmass;
  EvtVector4R qhat = q / parentmass;
 
  EvtComplex c7eff  = EvtbTosllAmp::GetC7Eff( q2, nnlo );
  EvtComplex c9eff  = EvtbTosllAmp::GetC9Eff( q2, nnlo, btod );
  EvtComplex c10eff = EvtbTosllAmp::GetC10Eff( q2, nnlo );
 
  // double mbhat=1;
  double mbhat = 4.4 / ( parentmass );
  // double mkhat = 0.15;
  double mkhat = mesonmass / ( parentmass );
  double shat  = q2 / ( parentmass * parentmass );
 
  double fm = ( f0 - fp ) * ( 1 - mkhat * mkhat ) / shat;
 
  EvtComplex aprime;
  aprime = c9eff * fp + 2.0 * mbhat * c7eff * ft / ( 1 + mkhat );
  EvtComplex bprime;
  bprime = c9eff * fm - 2 * mbhat * c7eff * ft * ( 1 - mkhat ) / shat;
 
  EvtComplex cprime;
  cprime = c10eff * fp;
  EvtComplex dprime;
  dprime = c10eff * fm;
 
  static EvtIdSet leptons( "e-", "mu-", "tau-" );
  static EvtIdSet antileptons( "e+", "mu+", "tau+" );
 
  if ( leptons.contains( l_num ) )
  {
 
    T1 = aprime * phat + bprime * qhat;
    T2 = cprime * phat + dprime * qhat;
 
    l11 = EvtLeptonVCurrent( parent->getDaug( 1 )->spParent( 0 ),
                             parent->getDaug( 2 )->spParent( 0 ) );
    l21 = EvtLeptonVCurrent( parent->getDaug( 1 )->spParent( 1 ),
                             parent->getDaug( 2 )->spParent( 0 ) );
    l12 = EvtLeptonVCurrent( parent->getDaug( 1 )->spParent( 0 ),
                             parent->getDaug( 2 )->spParent( 1 ) );
    l22 = EvtLeptonVCurrent( parent->getDaug( 1 )->spParent( 1 ),
                             parent->getDaug( 2 )->spParent( 1 ) );
    a11 = EvtLeptonACurrent( parent->getDaug( 1 )->spParent( 0 ),
                             parent->getDaug( 2 )->spParent( 0 ) );
    a21 = EvtLeptonACurrent( parent->getDaug( 1 )->spParent( 1 ),
                             parent->getDaug( 2 )->spParent( 0 ) );
    a12 = EvtLeptonACurrent( parent->getDaug( 1 )->spParent( 0 ),
                             parent->getDaug( 2 )->spParent( 1 ) );
    a22 = EvtLeptonACurrent( parent->getDaug( 1 )->spParent( 1 ),
                             parent->getDaug( 2 )->spParent( 1 ) );
  }
  else
  {
    if ( antileptons.contains( l_num ) )
    {
 
      T1 = aprime * phat + bprime * qhat;
      T2 = cprime * phat + dprime * qhat;
 
      l11 = EvtLeptonVCurrent( parent->getDaug( 1 )->spParent( 1 ),
                               parent->getDaug( 2 )->spParent( 1 ) );
      l21 = EvtLeptonVCurrent( parent->getDaug( 1 )->spParent( 0 ),
                               parent->getDaug( 2 )->spParent( 1 ) );
      l12 = EvtLeptonVCurrent( parent->getDaug( 1 )->spParent( 1 ),
                               parent->getDaug( 2 )->spParent( 0 ) );
      l22 = EvtLeptonVCurrent( parent->getDaug( 1 )->spParent( 0 ),
                               parent->getDaug( 2 )->spParent( 0 ) );
 
      a11 = EvtLeptonACurrent( parent->getDaug( 1 )->spParent( 1 ),
                               parent->getDaug( 2 )->spParent( 1 ) );
      a21 = EvtLeptonACurrent( parent->getDaug( 1 )->spParent( 0 ),
                               parent->getDaug( 2 )->spParent( 1 ) );
      a12 = EvtLeptonACurrent( parent->getDaug( 1 )->spParent( 1 ),
                               parent->getDaug( 2 )->spParent( 0 ) );
      a22 = EvtLeptonACurrent( parent->getDaug( 1 )->spParent( 0 ),
                               parent->getDaug( 2 )->spParent( 0 ) );
    }
    else { report( ERROR, "EvtGen" ) << "Wrong lepton number\n"; }
  }
 
  amp.vertex( 0, 0, l11 * T1 + a11 * T2 );
  amp.vertex( 0, 1, l12 * T1 + a12 * T2 );
  amp.vertex( 1, 0, l21 * T1 + a21 * T2 );
  amp.vertex( 1, 1, l22 * T1 + a22 * T2 );
}