/home/bes3soft/bes3soft/Boss/7.0.2/dist/7.0.2/Generator/BesEvtGen/BesEvtGen-00-03-58/src/EvtGen/EvtGenModels/EvtKstarstargamma.cc

Go to the documentation of this file.

//--------------------------------------------------------------------------
//
// 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) 2002      Caltech
//
// Module: EvtKstarstargamma.cc
//
// Description: Routine for the decau B->K**gamma
//
// Modification history:
//
//    Ryd       November 15, 2002       Module created
//
//------------------------------------------------------------------------
// 
#include "EvtGenBase/EvtPatches.hh"
#include <stdlib.h>
#include "EvtGenBase/EvtParticle.hh"
#include "EvtGenBase/EvtScalarParticle.hh"
#include "EvtGenBase/EvtVectorParticle.hh"
#include "EvtGenBase/EvtPhotonParticle.hh"
#include "EvtGenBase/EvtTensorParticle.hh"
#include "EvtGenBase/EvtGenKine.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtVector4C.hh"
#include "EvtGenBase/EvtVector4R.hh"
#include "EvtGenBase/EvtReport.hh"
#include "EvtGenModels/EvtKstarstargamma.hh"
#include <string>
#include "EvtGenBase/EvtEvalHelAmp.hh"
#include "EvtGenBase/EvtPropBreitWignerRel.hh"
#include "EvtGenBase/EvtTwoBodyVertex.hh"

EvtKstarstargamma::~EvtKstarstargamma() {}

void EvtKstarstargamma::getName(std::string& model_name){

  model_name="KSTARSTARGAMMA"; 
    
}


EvtDecayBase* EvtKstarstargamma::clone(){

  return new EvtKstarstargamma;

}

void EvtKstarstargamma::init(){

  // check that there are 0 arguments
  checkNArg(0);

  // check that there are 3 daughters
  checkNDaug(3);

  // check the parent and daughter spins
  checkSpinParent(EvtSpinType::SCALAR);
  checkSpinDaughter(0,EvtSpinType::SCALAR);
  checkSpinDaughter(1,EvtSpinType::SCALAR);
  checkSpinDaughter(2,EvtSpinType::PHOTON);
}

void EvtKstarstargamma::initProbMax() {

  //setProbMax(1.0);

}      

void EvtKstarstargamma::decay( EvtParticle *p){

  p->initializePhaseSpace(getNDaug(),getDaugs());

  EvtParticle* kaon = p->getDaug(0);
  EvtParticle* pion = p->getDaug(1);
  EvtParticle* photon = p->getDaug(2);


  EvtComplexPtrPtr Hd1=new EvtComplexPtr[5];
  Hd1[0]=new EvtComplex[2]; 
  Hd1[1]=new EvtComplex[2]; 
  Hd1[2]=new EvtComplex[2]; 
  Hd1[3]=new EvtComplex[2]; 
  Hd1[4]=new EvtComplex[2]; 

  Hd1[0][0]=0.0;
  Hd1[0][1]=0.0;
  Hd1[1][0]=0.0;
  Hd1[1][1]=0.0;
  Hd1[2][0]=0.0;
  Hd1[2][1]=0.0;
  Hd1[3][0]=0.0;
  Hd1[3][1]=1.0;
  Hd1[4][0]=0.0;
  Hd1[4][1]=0.0;

  EvtEvalHelAmp d1(EvtSpinType::SCALAR,EvtSpinType::TENSOR,
                   EvtSpinType::PHOTON,Hd1);

  EvtScalarParticle theB;

  theB.init(p->getId(),p->getP4Restframe());

  EvtVector4R theKstarP4=kaon->getP4()+pion->getP4();

  EvtTensorParticle theKstar;
  theKstar.init(EvtPDL::getId(std::string("K_2*0")),theKstarP4);

  EvtPhotonParticle thePhoton;
  thePhoton.init(EvtPDL::getId(std::string("K_2*0")),photon->getP4());

  theKstar.addDaug(&theB);
  thePhoton.addDaug(&theB);

  EvtAmp amp1;

  d1.evalAmp(&theB,amp1);

  EvtComplexPtrPtr Hd2=new EvtComplexPtr[1];
  Hd2[0]=new EvtComplex[1]; 

  Hd2[0][0]=1.0;


  EvtEvalHelAmp d2(EvtSpinType::TENSOR,EvtSpinType::SCALAR,
                   EvtSpinType::SCALAR,Hd2);
  
  
  EvtVector4R theKstarP4boost(theKstarP4.get(0),-theKstarP4.get(1),-theKstarP4.get(2),-theKstarP4.get(3));
  
  EvtScalarParticle theKaon;
  theKaon.init(EvtPDL::getId(std::string("K+")),boostTo(kaon->getP4(),theKstarP4boost));

  EvtScalarParticle thePion;
  thePion.init(EvtPDL::getId(std::string("pi+")),boostTo(pion->getP4(),theKstarP4boost));
            
  theKaon.addDaug(&theKstar);
  thePion.addDaug(&theKstar);

  // Calculate the propagator

  double m = theKstarP4.mass();
  EvtTwoBodyVertex v(0.5,0.14,1.4,2);
  EvtTwoBodyKine v1(0.5,0.14,m);
  EvtPropBreitWignerRel prop(1.4,0.2);

  // Mass-dependent width correction and amplitude calculation

  double width = prop.g0() * v.widthFactor(v1);
  prop.set_g0(width);
  EvtComplex bwamp = prop.evaluate(m);


  EvtAmp amp2;

  d2.evalAmp(&theKstar,amp2);

  vertex(0,bwamp*(amp1._amp[0]*amp2._amp[0]+
           amp1._amp[1]*amp2._amp[1]+
           amp1._amp[2]*amp2._amp[2]+
           amp1._amp[3]*amp2._amp[3]+
           amp1._amp[4]*amp2._amp[4]));

  vertex(1,bwamp*(amp1._amp[5]*amp2._amp[0]+
           amp1._amp[6]*amp2._amp[1]+
           amp1._amp[7]*amp2._amp[2]+
           amp1._amp[8]*amp2._amp[3]+
           amp1._amp[9]*amp2._amp[4]));
           
  return;
}

---