VectorSpinInfo.h

// -*- C++ -*-
//
// VectorSpinInfo.h is a part of ThePEG - Toolkit for HEP Event Generation
// Copyright (C) 2003-2019 Peter Richardson, Leif Lonnblad
//
// ThePEG is licenced under version 3 of the GPL, see COPYING for details.
// Please respect the MCnet academic guidelines, see GUIDELINES for details.
//
#ifndef THEPEG_VectorSpinInfo_H
#define THEPEG_VectorSpinInfo_H
// This is the declaration of the VectorSpinInfo class.

#include "ThePEG/EventRecord/SpinInfo.h"
#include "ThePEG/Helicity/LorentzPolarizationVector.h"
#include "VectorSpinInfo.fh"

namespace ThePEG {
namespace Helicity {

class VectorSpinInfo: public SpinInfo {

public:

  VectorSpinInfo() : SpinInfo(PDT::Spin1), _decaycalc(false) {}
  
  VectorSpinInfo(const Lorentz5Momentum & p, bool time)
    : SpinInfo(PDT::Spin1, p, time), _decaycalc(false) {}
  
public:

  void setBasisState(unsigned int hel, 
                     const LorentzPolarizationVector & in) const {
    assert(hel<3);
    _productionstates[hel] = in;
    _currentstates   [hel] = in;
  }

  void setDecayState(unsigned int hel, 
                     const LorentzPolarizationVector & in) const {
    assert(hel<3);
    _decaycalc = true;
    _decaystates[hel] = in;;
  }

  const LorentzPolarizationVector & getProductionBasisState(unsigned int hel) const {
    assert(hel<3);
    return _productionstates[hel];
  }

  const LorentzPolarizationVector & getCurrentBasisState(unsigned int hel) const {
    assert(hel<3);
    return _currentstates[hel];
  }

  const LorentzPolarizationVector & getDecayBasisState(unsigned int hel) const {
    assert(hel<3);
    if(!_decaycalc) {
      for(unsigned int ix=0;ix<3;++ix)
        _decaystates[ix]=_currentstates[ix].conjugate();
      _decaycalc=true;
    }
    // return the basis function
    return _decaystates[hel];
  }

  virtual void transform(const LorentzMomentum &,const LorentzRotation & );

  virtual void undecay() const {
    _decaycalc=false;
    SpinInfo::undecay();
  }

  virtual void reset() {
    undecay();
    _currentstates = _productionstates;
    SpinInfo::reset();
  }
  
public:

  static void Init();

  virtual EIPtr clone() const;

private:

  VectorSpinInfo & operator=(const VectorSpinInfo &) = delete;

private:

  mutable std::array<LorentzPolarizationVector,3> _productionstates;

  mutable std::array<LorentzPolarizationVector,3> _decaystates;

  mutable std::array<LorentzPolarizationVector,3> _currentstates;

  mutable bool _decaycalc;

};

}
}


namespace ThePEG {

}
#endif /* THEPEG_VectorSpinInfo_H */