BesEvtGen-00-04-08/src/EvtGen/EvtGenModels/EvtSLN.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: EvtSLN.cc
//
// Description: B ==> tau + nu
//
// Modification history:
//
//    RYD/SHY   April 23, 1997           Module created
//
//------------------------------------------------------------------------
//
#include "EvtGenBase/EvtPatches.hh"
#include <stdlib.h>
#include <iostream>
#include <string>
#include "EvtGenBase/EvtParticle.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtGenKine.hh"
#include "EvtGenModels/EvtSLN.hh"
#include "EvtGenBase/EvtDiracSpinor.hh"
#include "EvtGenBase/EvtReport.hh"
#include "EvtGenBase/EvtVector4C.hh"
 
EvtSLN::~EvtSLN() {}
 
void EvtSLN::getName(std::string& model_name){
 
  model_name="SLN";     
 
}
 
EvtDecayBase* EvtSLN::clone(){
 
  return new EvtSLN;
 
}
 
 
void EvtSLN::init(){
 
  // check that there are 0 arguments
  checkNArg(0);
  checkNDaug(2);
    
  checkSpinParent(EvtSpinType::SCALAR);
 
  checkSpinDaughter(0,EvtSpinType::DIRAC);
  checkSpinDaughter(1,EvtSpinType::NEUTRINO);
 
}
 
 
void EvtSLN::initProbMax(){
 
  double M=EvtPDL::getMeanMass(getParentId());
  double m=EvtPDL::getMeanMass(getDaug(0));
 
  double probMax=8.0*(M*M-m*m)*m*m;
 
  setProbMax(probMax);
 
}
 
 
void EvtSLN::decay(EvtParticle *p){
 
  static EvtId EM=EvtPDL::getId("e-");
  static EvtId MUM=EvtPDL::getId("mu-");
  static EvtId TAUM=EvtPDL::getId("tau-");
 
  p->initializePhaseSpace(getNDaug(),getDaugs());
 
  EvtParticle *l, *nul;
  l= p->getDaug(0);
  nul= p->getDaug(1);
 
  EvtVector4R p4_p;
  p4_p.set(p->mass(),0.0,0.0,0.0);
 
  EvtVector4C l1, l2;
  
  if (getDaug(0)==TAUM || getDaug(0)==MUM || getDaug(0)==EM) {
    l1=EvtLeptonVACurrent(l->spParent(0),nul->spParentNeutrino());
    l2=EvtLeptonVACurrent(l->spParent(1),nul->spParentNeutrino());
  }
  else{
    l1=EvtLeptonVACurrent(nul->spParentNeutrino(),l->spParent(0));
    l2=EvtLeptonVACurrent(nul->spParentNeutrino(),l->spParent(1));
  }
 
  vertex(0,p4_p*l1);
  vertex(1,p4_p*l2);
  
  return;
 
}