TEvtGen/EvtGenModels/EvtbTosllScalarAmp.cpp

   1 //--------------------------------------------------------------------------
   2 //
   3 // Environment:
   4 //      This software is part of the EvtGen package developed jointly
   5 //      for the BaBar and CLEO collaborations.  If you use all or part
   6 //      of it, please give an appropriate acknowledgement.
   7 //
   8 // Copyright Information: See EvtGen/COPYRIGHT
   9 //      Copyright (C) 2000      Caltech, UCSB
  10 //
  11 // Module: EvtbTosllScalarAmp.cc
  12 //
  13 // Description: Routine to implement bTosll decays to pseudo-scalar
  14 //              mesons.
  15 //
  16 // Modification history:
  17 //
  18 //    Ryd       January 5,2000       Module created
  19 //
  20 //------------------------------------------------------------------------
  21 //
  22 #include "EvtGenBase/EvtPatches.hh"
  23 #include "EvtGenBase/EvtConst.hh"
  24 #include "EvtGenBase/EvtPatches.hh"
  25 #include "EvtGenBase/EvtParticle.hh"
  26 #include "EvtGenBase/EvtGenKine.hh"
  27 #include "EvtGenBase/EvtPDL.hh"
  28 #include "EvtGenBase/EvtReport.hh"
  29 #include "EvtGenBase/EvtVector4C.hh"
  30 #include "EvtGenBase/EvtTensor4C.hh"
  31 #include "EvtGenBase/EvtDiracSpinor.hh"
  32 #include "EvtGenModels/EvtbTosllScalarAmp.hh"
  33 #include "EvtGenBase/EvtId.hh"
  34 #include "EvtGenBase/EvtIdSet.hh"
  35 #include "EvtGenBase/EvtAmp.hh"
  36 #include "EvtGenModels/EvtbTosllAmp.hh"
  37 #include "EvtGenModels/EvtbTosllFF.hh"
  38
  39 void EvtbTosllScalarAmp::CalcAmp( EvtParticle *parent,
  40                                   EvtAmp& amp,
  41                                   EvtbTosllFF *formFactors ) {
  42
  43   //Add the lepton and neutrino 4 momenta to find q2
  44
  45   EvtVector4R q = parent->getDaug(1)->getP4()
  46                     + parent->getDaug(2)->getP4();
  47   double q2 = (q.mass2());
  48
  49   double fp(0.),f0(0.),ft(0.);
  50   double mesonmass = parent->getDaug(0)->mass();
  51   double parentmass = parent->mass();
  52
  53   formFactors->getScalarFF(parent->getId(),
  54                            parent->getDaug(0)->getId(),
  55                            q2,
  56                            mesonmass,
  57                            fp,f0,ft);
  58
  59   EvtId daught = parent->getDaug(0)->getId();
  60   bool btod = false;
  61   bool nnlo = true;
  62   if (daught == EvtPDL::getId(std::string("pi+")) ||
  63           daught == EvtPDL::getId(std::string("pi-")) ||
  64           daught == EvtPDL::getId(std::string("pi0")) ||
  65           daught == EvtPDL::getId(std::string("eta")) ||
  66           daught == EvtPDL::getId(std::string("eta'"))
  67          )  btod = true;
  68
  69
  70   EvtVector4R p4b;
  71   p4b.set(parent->mass(),0.0,0.0,0.0);
  72
  73   EvtVector4C l11,l12;
  74   EvtVector4C l21,l22;
  75
  76   EvtVector4C a11,a12;
  77   EvtVector4C a21,a22;
  78
  79   EvtId l_num = parent->getDaug(1)->getId();
  80
  81   EvtVector4C T1,T2;
  82
  83   EvtVector4R phat=p4b/parentmass;
  84   EvtVector4R qhat=q/parentmass;
  85
  86   EvtComplex c7eff = EvtbTosllAmp::GetC7Eff(q2,nnlo);
  87   EvtComplex c9eff = EvtbTosllAmp::GetC9Eff(q2,nnlo,btod);
  88   EvtComplex c10eff = EvtbTosllAmp::GetC10Eff(q2,nnlo);
  89
  90   //double mbhat=1;
  91   double mbhat=4.4/(parentmass);
  92   //double mkhat = 0.15;
  93   double mkhat=mesonmass/(parentmass);
  94   double shat=q2/(parentmass*parentmass);
  95
  96   double fm=(f0-fp)*(1-mkhat*mkhat)/shat;
  97
  98   EvtComplex aprime;
  99   aprime = c9eff*fp+2.0*mbhat*c7eff*ft/(1+mkhat);
 100   EvtComplex bprime;
 101   bprime = c9eff*fm-2*mbhat*c7eff*ft*(1-mkhat)/shat;
 102
 103   EvtComplex cprime;
 104   cprime = c10eff*fp;
 105   EvtComplex dprime;
 106   dprime = c10eff*fm;
 107
 108   static EvtIdSet leptons("e-","mu-","tau-");
 109   static EvtIdSet antileptons("e+","mu+","tau+");
 110
 111   if (leptons.contains(l_num)){
 112
 113     T1=aprime*phat+bprime*qhat;
 114     T2=cprime*phat+dprime*qhat;
 115
 116     l11=EvtLeptonVCurrent(parent->getDaug(1)->spParent(0),
 117                           parent->getDaug(2)->spParent(0));
 118     l21=EvtLeptonVCurrent(parent->getDaug(1)->spParent(1),
 119                           parent->getDaug(2)->spParent(0));
 120     l12=EvtLeptonVCurrent(parent->getDaug(1)->spParent(0),
 121                           parent->getDaug(2)->spParent(1));
 122     l22=EvtLeptonVCurrent(parent->getDaug(1)->spParent(1),
 123                           parent->getDaug(2)->spParent(1));
 124     a11=EvtLeptonACurrent(parent->getDaug(1)->spParent(0),
 125                           parent->getDaug(2)->spParent(0));
 126     a21=EvtLeptonACurrent(parent->getDaug(1)->spParent(1),
 127                           parent->getDaug(2)->spParent(0));
 128     a12=EvtLeptonACurrent(parent->getDaug(1)->spParent(0),
 129                           parent->getDaug(2)->spParent(1));
 130     a22=EvtLeptonACurrent(parent->getDaug(1)->spParent(1),
 131                           parent->getDaug(2)->spParent(1));
 132   }
 133   else{
 134     if (antileptons.contains(l_num)){
 135
 136     T1=aprime*phat+bprime*qhat;
 137     T2=cprime*phat+dprime*qhat;
 138
 139     l11=EvtLeptonVCurrent(parent->getDaug(1)->spParent(1),
 140                           parent->getDaug(2)->spParent(1));
 141     l21=EvtLeptonVCurrent(parent->getDaug(1)->spParent(0),
 142                           parent->getDaug(2)->spParent(1));
 143     l12=EvtLeptonVCurrent(parent->getDaug(1)->spParent(1),
 144                           parent->getDaug(2)->spParent(0));
 145     l22=EvtLeptonVCurrent(parent->getDaug(1)->spParent(0),
 146                           parent->getDaug(2)->spParent(0));
 147
 148     a11=EvtLeptonACurrent(parent->getDaug(1)->spParent(1),
 149                           parent->getDaug(2)->spParent(1));
 150     a21=EvtLeptonACurrent(parent->getDaug(1)->spParent(0),
 151                           parent->getDaug(2)->spParent(1));
 152     a12=EvtLeptonACurrent(parent->getDaug(1)->spParent(1),
 153                           parent->getDaug(2)->spParent(0));
 154     a22=EvtLeptonACurrent(parent->getDaug(1)->spParent(0),
 155                           parent->getDaug(2)->spParent(0));
 156
 157     }
 158     else{
 159       report(ERROR,"EvtGen") << "Wrong lepton number\n";
 160     }
 161   }
 162
 163   amp.vertex(0,0,l11*T1+a11*T2);
 164   amp.vertex(0,1,l12*T1+a12*T2);
 165   amp.vertex(1,0,l21*T1+a21*T2);
 166   amp.vertex(1,1,l22*T1+a22*T2);
 167
 168 }
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