EvtRaritaSchwingerParticle.cpp

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#include "EvtGenBase/EvtRaritaSchwingerParticle.hh"

#include "EvtGenBase/EvtComplex.hh"
#include "EvtGenBase/EvtDiracSpinor.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtPatches.hh"
#include "EvtGenBase/EvtReport.hh"
#include "EvtGenBase/EvtVector4R.hh"

#include <iostream>
#include <math.h>
#include <stdlib.h>
using std::endl;

void EvtRaritaSchwingerParticle::init( EvtId id, const EvtVector4R& p4 )
{
    _validP4 = true;
    setp( p4 );
    setpart_num( id );

    if ( EvtPDL::getStdHep( id ) == 0 ) {
        EvtGenReport( EVTGEN_ERROR, "EvtGen" )
            << "Error in EvtRaritaSchwingerParticle::init, part_n=" << id.getId()
            << endl;
        ::abort();
    }

    double sqmt2 = sqrt( 2.0 * ( this->getP4().mass() ) );

    EvtDiracSpinor spplus;
    EvtDiracSpinor spminus;

    if ( EvtPDL::getStdHep( getId() ) > 0 ) {
        spplus.set( sqmt2, 0.0, 0.0, 0.0 );
        spminus.set( 0.0, sqmt2, 0.0, 0.0 );
    } else {
        spplus.set( 0.0, 0.0, sqmt2, 0.0 );
        spminus.set( 0.0, 0.0, 0.0, sqmt2 );
    }

    static EvtVector4C eplus( 0.0, -1.0 / sqrt( 2.0 ),
                              EvtComplex( 0.0, -1.0 / sqrt( 2.0 ) ), 0.0 );
    static EvtVector4C ezero( 0.0, 0.0, 0.0, 1.0 );
    static EvtVector4C eminus( 0.0, 1.0 / sqrt( 2.0 ),
                               EvtComplex( 0.0, -1.0 / sqrt( 2.0 ) ), 0.0 );

    _spinorRest[0] = dirProd( eplus, spplus );
    _spinorRest[1] = dirProd( sqrt( 2.0 / 3.0 ) * ezero, spplus ) +
                     dirProd( sqrt( 1.0 / 3.0 ) * eplus, spminus );
    _spinorRest[2] = dirProd( sqrt( 2.0 / 3.0 ) * ezero, spminus ) +
                     dirProd( sqrt( 1.0 / 3.0 ) * eminus, spplus );
    _spinorRest[3] = dirProd( eminus, spminus );

    _spinor[0] = boostTo( _spinorRest[0], p4 );
    _spinor[1] = boostTo( _spinorRest[1], p4 );
    _spinor[2] = boostTo( _spinorRest[2], p4 );
    _spinor[3] = boostTo( _spinorRest[3], p4 );

    setLifetime();
}

void EvtRaritaSchwingerParticle::init(
    EvtId id, const EvtVector4R& p4, const EvtRaritaSchwinger& prod1,
    const EvtRaritaSchwinger& prod2, const EvtRaritaSchwinger& prod3,
    const EvtRaritaSchwinger& prod4, const EvtRaritaSchwinger& rest1,
    const EvtRaritaSchwinger& rest2, const EvtRaritaSchwinger& rest3,
    const EvtRaritaSchwinger& rest4 )
{
    _validP4 = true;
    setp( p4 );
    setpart_num( id );

    if ( EvtPDL::getStdHep( id ) == 0 ) {
        EvtGenReport( EVTGEN_ERROR, "EvtGen" )
            << "Error in EvtRaritaSchwingerParticle::init, part_n=" << id.getId()
            << std::endl;
        ::abort();
    }
    _spinorRest[0] = rest1;
    _spinorRest[1] = rest2;
    _spinorRest[2] = rest3;
    _spinorRest[3] = rest4;

    _spinor[0] = prod1;
    _spinor[1] = prod2;
    _spinor[2] = prod3;
    _spinor[3] = prod4;

    setLifetime();
}

EvtRaritaSchwinger EvtRaritaSchwingerParticle::spRSParent( int i ) const
{
    return _spinor[i];
}

EvtRaritaSchwinger EvtRaritaSchwingerParticle::spRS( int i ) const
{
    return _spinorRest[i];
}

EvtSpinDensity EvtRaritaSchwingerParticle::rotateToHelicityBasis() const
{
    double sqmt2 = sqrt( 2.0 * ( this->getP4().mass() ) );

    EvtDiracSpinor spplus;
    EvtDiracSpinor spminus;

    if ( EvtPDL::getStdHep( getId() ) > 0 ) {
        spplus.set( 1.0, 0.0, 0.0, 0.0 );
        spminus.set( 0.0, 1.0, 0.0, 0.0 );
    } else {
        spplus.set( 0.0, 0.0, 1.0, 0.0 );
        spminus.set( 0.0, 0.0, 0.0, 1.0 );
    }

    EvtVector4C eplus( 0.0, -1.0 / sqrt( 2.0 ),
                       EvtComplex( 0.0, -1.0 / sqrt( 2.0 ) ), 0.0 );
    EvtVector4C ezero( 0.0, 0.0, 0.0, 1.0 );
    EvtVector4C eminus( 0.0, 1.0 / sqrt( 2.0 ),
                        EvtComplex( 0.0, -1.0 / sqrt( 2.0 ) ), 0.0 );

    EvtRaritaSchwinger sppp = dirProd( eplus, spplus );
    EvtRaritaSchwinger spp = dirProd( sqrt( 2.0 / 3.0 ) * ezero, spplus ) +
                             dirProd( sqrt( 1.0 / 3.0 ) * eplus, spminus );
    EvtRaritaSchwinger spm = dirProd( sqrt( 2.0 / 3.0 ) * ezero, spminus ) +
                             dirProd( sqrt( 1.0 / 3.0 ) * eminus, spplus );
    EvtRaritaSchwinger spmm = dirProd( eminus, spminus );

    EvtSpinDensity R;
    R.setDim( 4 );

    for ( int i = 0; i < 4; i++ ) {
        R.set( 0, i, ( sppp * _spinorRest[i] ) / sqmt2 );
        R.set( 1, i, ( spp * _spinorRest[i] ) / sqmt2 );
        R.set( 2, i, ( spm * _spinorRest[i] ) / sqmt2 );
        R.set( 3, i, ( spmm * _spinorRest[i] ) / sqmt2 );
    }

    return R;
}

EvtSpinDensity EvtRaritaSchwingerParticle::rotateToHelicityBasis(
    double alpha, double beta, double gamma ) const
{
    EvtDiracSpinor spplus;
    EvtDiracSpinor spminus;

    if ( EvtPDL::getStdHep( getId() ) > 0 ) {
        spplus.set( 1.0, 0.0, 0.0, 0.0 );
        spminus.set( 0.0, 1.0, 0.0, 0.0 );
    } else {
        spplus.set( 0.0, 0.0, 1.0, 0.0 );
        spminus.set( 0.0, 0.0, 0.0, 1.0 );
    }

    EvtVector4C eplus( 0.0, -1.0 / sqrt( 2.0 ),
                       EvtComplex( 0.0, -1.0 / sqrt( 2.0 ) ), 0.0 );
    EvtVector4C ezero( 0.0, 0.0, 0.0, 1.0 );
    EvtVector4C eminus( 0.0, 1.0 / sqrt( 2.0 ),
                        EvtComplex( 0.0, -1.0 / sqrt( 2.0 ) ), 0.0 );

    EvtRaritaSchwinger sppp = dirProd( eplus, spplus );
    EvtRaritaSchwinger spp = dirProd( sqrt( 2.0 / 3.0 ) * ezero, spplus ) +
                             dirProd( sqrt( 1.0 / 3.0 ) * eplus, spminus );
    EvtRaritaSchwinger spm = dirProd( sqrt( 2.0 / 3.0 ) * ezero, spminus ) +
                             dirProd( sqrt( 1.0 / 3.0 ) * eminus, spplus );
    EvtRaritaSchwinger spmm = dirProd( eminus, spminus );

    sppp.applyRotateEuler( alpha, beta, gamma );
    spp.applyRotateEuler( alpha, beta, gamma );
    spm.applyRotateEuler( alpha, beta, gamma );
    spmm.applyRotateEuler( alpha, beta, gamma );

    EvtSpinDensity R;
    R.setDim( 4 );

    double sqmt2 = sqrt( 2.0 * ( this->getP4().mass() ) );

    for ( int i = 0; i < 4; i++ ) {
        R.set( 0, i, ( sppp * _spinorRest[i] ) / sqmt2 );
        R.set( 1, i, ( spp * _spinorRest[i] ) / sqmt2 );
        R.set( 2, i, ( spm * _spinorRest[i] ) / sqmt2 );
        R.set( 3, i, ( spmm * _spinorRest[i] ) / sqmt2 );
    }

    return R;
}