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[u/mrichter/AliRoot.git] / TEvtGen / EvtGenModels / EvtSTSCP.cxx

//--------------------------------------------------------------------------
//
// 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: EvtSTSCP.cc
//
// Description: Routine to decay scalar -> tensor scalar
//              and has CP violation.
//
// Modification history:
//
//    RYD       June 19, 1997       Module created
//
//------------------------------------------------------------------------
// 
#include "EvtGenBase/EvtPatches.hh"
#include <stdlib.h>
#include "EvtGenBase/EvtParticle.hh"
#include "EvtGenBase/EvtGenKine.hh"
#include "EvtGenBase/EvtCPUtil.hh"
#include "EvtGenBase/EvtTensor4C.hh"
#include "EvtGenBase/EvtVector4C.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtReport.hh"
#include "EvtGenModels/EvtSTSCP.hh"
#include "EvtGenBase/EvtId.hh"
#include <string>
#include "EvtGenBase/EvtConst.hh"

EvtSTSCP::~EvtSTSCP() {}

std::string EvtSTSCP::getName(){

  return "STS_CP";     

}

void EvtSTSCP::initProbMax(){

  //This is probably not quite right, but it should do as a start...
  //Anders

  setProbMax(20*(getArg(3)*getArg(3)+getArg(5)*getArg(5)));

}

EvtDecayBase* EvtSTSCP::clone(){

  return new EvtSTSCP;

}

void EvtSTSCP::init(){

  // check that there are 7 arguments
  checkNArg(7);
  checkNDaug(2);

  checkSpinParent(EvtSpinType::SCALAR);

  checkSpinDaughter(0,EvtSpinType::TENSOR);
  checkSpinDaughter(1,EvtSpinType::SCALAR);

}


void EvtSTSCP::decay( EvtParticle *p){

  //added by Lange Jan4,2000
  static EvtId B0=EvtPDL::getId("B0");
  static EvtId B0B=EvtPDL::getId("anti-B0");

  double t;
  EvtId other_b;

  EvtParticle *t1;
  p->initializePhaseSpace(getNDaug(),getDaugs());
  t1 = p->getDaug(0);
  EvtVector4R momt = t1->getP4();
  EvtVector4R moms = p->getDaug(1)->getP4();
  double masst = t1->mass();

  EvtCPUtil::OtherB(p,t,other_b);

  double m_parent = p->mass();

   EvtComplex amp;

   EvtComplex A,Abar;

   A=EvtComplex(getArg(3)*cos(getArg(4)),getArg(3)*sin(getArg(4)));
   Abar=EvtComplex(getArg(5)*cos(getArg(6)),getArg(5)*sin(getArg(6)));

   if (other_b==B0B){
     amp=A*cos(getArg(1)*t/(2*EvtConst::c))+
       EvtComplex(cos(-2.0*getArg(0)),sin(-2.0*getArg(0)))*
       getArg(2)*EvtComplex(0.0,1.0)*Abar*sin(getArg(1)*t/(2*EvtConst::c));
   }
   if (other_b==B0){
     amp=A*EvtComplex(cos(2.0*getArg(0)),sin(2.0*getArg(0)))*
       EvtComplex(0.0,1.0)*sin(getArg(1)*t/(2*EvtConst::c))+       
       getArg(2)*Abar*cos(getArg(1)*t/(2*EvtConst::c));
   }

  EvtVector4R p4_parent;

  p4_parent=momt+moms;

  double norm=masst*masst/(m_parent*momt.d3mag()*momt.d3mag());
 
   
   vertex(0,amp*norm*t1->epsTensorParent(0).cont1(p4_parent)*p4_parent);
   vertex(1,amp*norm*t1->epsTensorParent(1).cont1(p4_parent)*p4_parent);
   vertex(2,amp*norm*t1->epsTensorParent(2).cont1(p4_parent)*p4_parent);
   vertex(3,amp*norm*t1->epsTensorParent(3).cont1(p4_parent)*p4_parent);
   vertex(4,amp*norm*t1->epsTensorParent(4).cont1(p4_parent)*p4_parent);

  return ;
}