BesEvtGen-00-04-08/src/EvtGen/EvtGenModels/EvtBTo3piCP.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: EvtBTo3piCP.cc
//
// Description: Routine to decay B->pi+ pi- pi0
//              and has CP violation.
//
// Modification history:
//
//    RYD/VERSILLE     March 2, 1997        Module created
//
//------------------------------------------------------------------------
//
#include "EvtGenBase/EvtPatches.hh"
#include <stdlib.h>
#include "EvtGenBase/EvtParticle.hh"
#include "EvtGenBase/EvtCPUtil.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtReport.hh"
#include "EvtGenModels/EvtBTo3piCP.hh"
#include "EvtGenBase/EvtId.hh"
#include <string>
#include "EvtGenBase/EvtConst.hh"
 
extern "C" {
  extern void evt3pions_(double *,int *,double *,
             double *,double *,double *,double *,
             double *,double *,double *);
}
 
 
EvtBTo3piCP::~EvtBTo3piCP() {}
 
 
void EvtBTo3piCP::getName(std::string& model_name){
 
  model_name="BTO3PI_CP";     
 
}
 
 
EvtDecayBase* EvtBTo3piCP::clone(){
 
  return new EvtBTo3piCP;
 
}
 
void EvtBTo3piCP::init(){
 
  // check that there are 2 arguments
  checkNArg(2);
  checkNDaug(3);
 
  checkSpinParent(EvtSpinType::SCALAR);
 
  checkSpinDaughter(0,EvtSpinType::SCALAR);
  checkSpinDaughter(1,EvtSpinType::SCALAR);
  checkSpinDaughter(2,EvtSpinType::SCALAR);
}
 
 
 
void EvtBTo3piCP::initProbMax(){
 
  setProbMax(1.5);
 
}
 
void EvtBTo3piCP::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;
 
  EvtCPUtil::OtherB(p,t,other_b);
 
  EvtParticle *pip,*pim,*pi0;
 
  p->makeDaughters(getNDaug(),getDaugs());
 
  //  p->init_daug(SCALAR,&pip,SCALAR,&pim,SCALAR,&pi0);
  pip=p->getDaug(0);
  pim=p->getDaug(1);
  pi0=p->getDaug(2);
 
  EvtVector4R p4[3];
 
  double dm=getArg(0);
  double alpha=getArg(1);
  int iset;
 
  static int first=1;
 
  if (first==1) {
    iset=10000;
    first=0;
  }
  else{
    iset=0;
  }
 
  double p4piplus[4],p4piminus[4],p4gamm1[4],p4gamm2[4]; 
 
  double realA,imgA,realbarA,imgbarA;
 
  evt3pions_(&alpha,&iset,p4piplus,p4piminus,p4gamm1,p4gamm2,
         &realA,&imgA,&realbarA,&imgbarA);
 
  p4[0].set(p4piplus[3],p4piplus[0],p4piplus[1],p4piplus[2]);
  p4[1].set(p4piminus[3],p4piminus[0],p4piminus[1],p4piminus[2]);
  p4[2].set(p4gamm1[3]+p4gamm2[3],p4gamm1[0]+p4gamm2[0],
        p4gamm1[1]+p4gamm2[1],p4gamm1[2]+p4gamm2[2]);
 
  if (pip->getId()==EvtPDL::getId("pi+")) {
    pip->init( getDaug(0), p4[0] );
    pim->init( getDaug(1), p4[1] );
  }
  else {
    pip->init( getDaug(0), p4[1] );
    pim->init( getDaug(1), p4[0] );  
  }
 
   pi0->init( getDaug(2), p4[2] );
   
   EvtComplex amp;
 
   EvtComplex A(realA,imgA);
   EvtComplex Abar(realbarA,imgbarA);
 
   if (other_b==B0B){
     amp=A*cos(dm*t/(2*EvtConst::c))+
       EvtComplex(0.,1.)*Abar*sin(dm*t/(2*EvtConst::c));
   }
   if (other_b==B0){
     amp=Abar*cos(dm*t/(2*EvtConst::c))+
       EvtComplex(0.,1.)*A*sin(dm*t/(2*EvtConst::c));
   }
 
   vertex(amp);
 
  return ;
}