EvtChi1BB1.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: EvtChi1BB1.cc
//
// Description: Routine to decay Chi1 to B8 B8bar.
//
// Modification history:
//
// Pang C.Y. and Ping R.-G.       April, 2007       Module created
//
//------------------------------------------------------------------------
//
#include "EvtChi1BB1.hh"
#include "../EvtGenBase/EvtGenKine.hh"
#include "../EvtGenBase/EvtHelSys.hh"
#include "../EvtGenBase/EvtPDL.hh"
#include "../EvtGenBase/EvtParticle.hh"
#include "../EvtGenBase/EvtPatches.hh"
#include "../EvtGenBase/EvtReport.hh"
#include "../EvtGenBase/EvtTensor4C.hh"
#include "../EvtGenBase/EvtVector4C.hh"
#include "../EvtGenBase/EvtVector4R.hh"
#include "../EvtGenBase/EvtdFunction.hh"
#include <stdlib.h>
#include <string>
using std::cout;
using std::endl;
EvtChi1BB1::~EvtChi1BB1() {}
 
void EvtChi1BB1::getName( std::string& model_name ) { model_name = "Chi1BB1"; }
 
EvtDecayBase* EvtChi1BB1::clone() { return new EvtChi1BB1; }
 
void EvtChi1BB1::init() {
  // check that there are 1 arguments
  checkNArg( 2 );
  checkNDaug( 2 );
  checkSpinParent( EvtSpinType::VECTOR );
  checkSpinDaughter( 0, EvtSpinType::DIRAC );
  checkSpinDaughter( 1, EvtSpinType::DIRAC );
}
 
/*
void EvtChi1BB1::initProbMax() {
 
  //Hard coded... should not be hard to calculate...
 setProbMax(100.0);
 
}
*/
 
void EvtChi1BB1::decay( EvtParticle* p ) {
 
  p->initializePhaseSpace( getNDaug(), getDaugs() );
 
  EvtParticle *v, *s1;
  EvtVector4R  pv, ps, ppr;
 
  v   = p->getDaug( 0 );
  s1  = p->getDaug( 1 );
  pv  = v->getP4();
  ps  = s1->getP4();
  ppr = p->getP4();
 
  //  Put phase space results into the daughters.
  EvtHelSys angles( ppr, pv ); // using helicity sys. angles
  double    theta = angles.getHelAng( 1 );
  double    phi   = angles.getHelAng( 2 );
  double    gamma = 0;
 
  /* double alpha=getArg(0);
   double F01=sqrt((1+alpha)/2);
   double F00=sqrt((1-alpha)/4);
  */
 
  double F01 = getArg( 0 );
  double F00 = getArg( 1 );
  double F10 = -F01;
  double F11 = -F00;
  // cout<<"**************F00,F01,F10,F11="<<F00<<F01<<F10<<F11<<endl;
  vertex( 0, 0, 0, Djmn( 1, 1, 0, phi, theta, gamma ) * F00 ); // Chi1  helicity =1
                                                               // corresponding index=0
  vertex( 0, 0, 1, Djmn( 1, 1, 1, phi, theta, gamma ) * F01 );
  vertex( 0, 1, 0, Djmn( 1, 1, -1, phi, theta, gamma ) * F10 );
  vertex( 0, 1, 1, Djmn( 1, 1, 0, phi, theta, gamma ) * F11 );
 
  vertex( 1, 0, 0, Djmn( 1, -1, 0, phi, theta, gamma ) * F00 ); // Chi1  helicity =-1
                                                                // corresponding index=1
  vertex( 1, 0, 1, Djmn( 1, -1, 1, phi, theta, gamma ) * F01 );
  vertex( 1, 1, 0, Djmn( 1, -1, -1, phi, theta, gamma ) * F10 );
  vertex( 1, 1, 1, Djmn( 1, -1, 0, phi, theta, gamma ) * F11 );
 
  vertex( 2, 0, 0, Djmn( 1, 0, 0, phi, theta, gamma ) * F00 ); // Chi1  helicity =0
                                                               // corresponding index=2
  vertex( 2, 0, 1, Djmn( 1, 0, 1, phi, theta, gamma ) * F01 );
  vertex( 2, 1, 0, Djmn( 1, 0, -1, phi, theta, gamma ) * F10 );
  vertex( 2, 1, 1, Djmn( 1, 0, 0, phi, theta, gamma ) * F11 );
 
  return;
}