EvtAmp.hh

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* Copyright 1998-2020 CERN for the benefit of the EvtGen authors       *
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#ifndef EVTAMP_HH
#define EVTAMP_HH

#include "EvtGenBase/EvtComplex.hh"
#include "EvtGenBase/EvtPatches.hh"

class EvtSpinDensity;
class EvtId;

class EvtAmp {
  public:
    EvtAmp();
    EvtAmp( const EvtAmp& amp );

    void init( EvtId p, int ndaug, EvtId* daug );

    void setAmp( int* ind, const EvtComplex& amp );

    const EvtComplex& getAmp( int* ind ) const;

    EvtSpinDensity getSpinDensity();

    EvtSpinDensity contract( int i, const EvtAmp& a );
    EvtAmp contract( int i, const EvtSpinDensity& rho );

    //sum over the i:th daugther of a1 and contract with parent of a2
    EvtAmp contract( int i, const EvtAmp& a1, const EvtAmp& a2 );

    EvtSpinDensity getForwardSpinDensity( EvtSpinDensity* rho_list, int k );
    EvtSpinDensity getBackwardSpinDensity( EvtSpinDensity* rho_list );

    EvtAmp& operator=( const EvtAmp& amp );

    void vertex( const EvtComplex& amp );

    void vertex( int i1, const EvtComplex& amp );

    void vertex( int i1, int i2, const EvtComplex& amp );

    void vertex( int i1, int i2, int i3, const EvtComplex& amp );

    void vertex( int* i1, const EvtComplex& amp );

    void dump();

  private:
    friend class EvtDecayAmp;
    friend class EvtKstarstargamma;

    void setNDaug( int n );
    void setNState( int parent_states, int* daug_states );

    // the amplitudes
    EvtComplex _amp[125];

    // the number of daughters
    int _ndaug;

    // the number of states of the parent
    int _pstates;

    // number of states of the daughter
    int dstates[10];

    // the nontrivial index of the daughter
    int _dnontrivial[10];

    // number of nontrivial daugts+parent
    int _nontrivial;

    // compact nstates
    int _nstate[5];
};

#endif