EvtJTO3P.cc

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//--------------------------------------------------------------------------
//
// Environment:
//      This software is part of models developed at BES collaboration
//      based on the EvtGen framework.  If you use all or part
//      of it, please give an appropriate acknowledgement.
//
// Copyright Information: See EvtGen/BesCopyright
//      Copyright (A) 2006      Ping Rong-Gang @IHEP
//
// Module:  EvtJTO3P.cc
//
// Description: Routine to a vector decays into 3 pseudoscalar with only contact term
 
//
// Modification history:
//
//  Ping R.-G.    December, 2007       Module created
//
//------------------------------------------------------------------------
 
#include "EvtJTO3P.hh"
#include "../EvtGenBase/EvtDiracParticle.hh"
#include "../EvtGenBase/EvtEulerAngles.hh"
#include "../EvtGenBase/EvtGenKine.hh"
#include "../EvtGenBase/EvtHighSpinParticle.hh"
#include "../EvtGenBase/EvtNeutrinoParticle.hh"
#include "../EvtGenBase/EvtPDL.hh"
#include "../EvtGenBase/EvtParticle.hh"
#include "../EvtGenBase/EvtPatches.hh"
#include "../EvtGenBase/EvtPhotonParticle.hh"
#include "../EvtGenBase/EvtRandom.hh"
#include "../EvtGenBase/EvtRaritaSchwingerParticle.hh"
#include "../EvtGenBase/EvtReport.hh"
#include "../EvtGenBase/EvtScalarParticle.hh"
#include "../EvtGenBase/EvtStringParticle.hh"
#include "../EvtGenBase/EvtTensor4C.hh"
#include "../EvtGenBase/EvtTensorParticle.hh"
#include "../EvtGenBase/EvtVector4C.hh"
#include "../EvtGenBase/EvtVector4R.hh"
#include "../EvtGenBase/EvtVectorParticle.hh"
#include <stdlib.h>
#include <string>
using namespace std; //::endl;
 
EvtJTO3P::~EvtJTO3P() {}
 
void EvtJTO3P::getName( std::string& model_name ) { model_name = "JTO3P"; }
 
EvtDecayBase* EvtJTO3P::clone() { return new EvtJTO3P; }
 
void EvtJTO3P::init() {
 
  // check that there are 1 arguments:angular distribution parameter
  //  checkNArg(0);
  checkNDaug( 3 );
  checkSpinParent( EvtSpinType::VECTOR );
  checkSpinDaughter( 0, EvtSpinType::SCALAR );
  checkSpinDaughter( 1, EvtSpinType::SCALAR );
  checkSpinDaughter( 2, EvtSpinType::SCALAR );
}
 
// void EvtJTO3P::initProbMax(){
//  setProbMax(1.0);
// }
 
void EvtJTO3P::decay( EvtParticle* p ) {
 
  p->initializePhaseSpace( getNDaug(), getDaugs() );
 
  EvtVector4R mompi1 = p->getDaug( 0 )->getP4();
  EvtVector4R mompi2 = p->getDaug( 1 )->getP4();
  EvtVector4R mompi3 = p->getDaug( 2 )->getP4();
  EvtVector4R Zaxis  = mompi2.cross( mompi3 );
 
  EvtEulerAngles EA( mompi1, Zaxis );
  double         alpha = EA.getAlpha();
  double         beta  = EA.getBeta();
  double         gamma = EA.getGamma();
 
  EvtVector4R h1, h2; // rotate pi1 and pi2 momentum to helicity system
  h1 = rotateEuler( mompi1, -gamma, -beta, -alpha );
  h2 = rotateEuler( mompi2, -gamma, -beta, -alpha );
  //       cout<<h1<<h2<<endl;
  double F0 = h1.get( 1 ) * h2.get( 2 ) - h1.get( 2 ) * h2.get( 1 );
  //       cout<<"F0 = "<<F0<<endl;
 
  vertex( 0, Djmn( 1, 1, 0, alpha, beta, gamma ) * F0 );
  vertex( 1, Djmn( 1, -1, 0, alpha, beta, gamma ) * F0 );
  vertex( 2, Djmn( 1, 0, 0, alpha, beta, gamma ) * F0 );
}