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 "EvtParticle.hh"
#include "EvtVector4C.hh"
// #include "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