BesEvtGen-00-04-08/src/EvtGen/EvtGenBase/EvtPhotonParticle.hh

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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: EvtGen/EvtPhotonParticle.hh
//
// Description:Class to describe photons
//
// Modification history:
//
//    DJL/RYD     Sept. 25, 1996         Module created
//
//------------------------------------------------------------------------
 
#ifndef EVTPHOTONPARTICLE_HH
#define EVTPHOTONPARTICLE_HH
 
#include "EvtGenBase/EvtVector4C.hh"
#include "EvtGenBase/EvtParticle.hh"
//#include "EvtGenBase/EvtId.hh"
class EvtId;
 
//Class to handle massless spin 1 particles.
 
class EvtPhotonParticle: public EvtParticle {
 
public:
 
  EvtPhotonParticle(){}
  virtual ~EvtPhotonParticle();
 
  void init(EvtId part_n,double e,double px,double py,double pz);
  void init(EvtId part_n,const EvtVector4R& p4);
 
  //Return polarization vectors
  EvtVector4C epsParentPhoton(int i); 
  EvtVector4C epsPhoton(int i); 
 
 
  EvtSpinDensity rotateToHelicityBasis() const;
  EvtSpinDensity rotateToHelicityBasis(double alpha,
                       double beta,
                       double gamma) const;
 
private:
 
  EvtVector4C eps1,eps2;
  int _evalBasis;
 
  EvtPhotonParticle(const EvtPhotonParticle& photon);
  EvtPhotonParticle& operator=(const EvtPhotonParticle& photon);
 
};
 
#endif