EvtRaritaSchwingerParticle.cpp

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#include "EvtGenBase/EvtRaritaSchwingerParticle.hh"
 
#include "EvtGenBase/EvtComplex.hh"
#include "EvtGenBase/EvtDiracSpinor.hh"
#include "EvtGenBase/EvtPDL.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 )
{
    m_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 const EvtVector4C eplus( 0.0, -1.0 / sqrt( 2.0 ),
                                    EvtComplex( 0.0, -1.0 / sqrt( 2.0 ) ), 0.0 );
    static const EvtVector4C ezero( 0.0, 0.0, 0.0, 1.0 );
    static const EvtVector4C eminus( 0.0, 1.0 / sqrt( 2.0 ),
                                     EvtComplex( 0.0, -1.0 / sqrt( 2.0 ) ), 0.0 );
 
    m_spinorRest[0] = dirProd( eplus, spplus );
    m_spinorRest[1] = dirProd( sqrt( 2.0 / 3.0 ) * ezero, spplus ) +
                      dirProd( sqrt( 1.0 / 3.0 ) * eplus, spminus );
    m_spinorRest[2] = dirProd( sqrt( 2.0 / 3.0 ) * ezero, spminus ) +
                      dirProd( sqrt( 1.0 / 3.0 ) * eminus, spplus );
    m_spinorRest[3] = dirProd( eminus, spminus );
 
    m_spinor[0] = boostTo( m_spinorRest[0], p4 );
    m_spinor[1] = boostTo( m_spinorRest[1], p4 );
    m_spinor[2] = boostTo( m_spinorRest[2], p4 );
    m_spinor[3] = boostTo( m_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 )
{
    m_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();
    }
    m_spinorRest[0] = rest1;
    m_spinorRest[1] = rest2;
    m_spinorRest[2] = rest3;
    m_spinorRest[3] = rest4;
 
    m_spinor[0] = prod1;
    m_spinor[1] = prod2;
    m_spinor[2] = prod3;
    m_spinor[3] = prod4;
 
    setLifetime();
}
 
EvtRaritaSchwinger EvtRaritaSchwingerParticle::spRSParent( int i ) const
{
    return m_spinor[i];
}
 
EvtRaritaSchwinger EvtRaritaSchwingerParticle::spRS( int i ) const
{
    return m_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 * m_spinorRest[i] ) / sqmt2 );
        R.set( 1, i, ( spp * m_spinorRest[i] ) / sqmt2 );
        R.set( 2, i, ( spm * m_spinorRest[i] ) / sqmt2 );
        R.set( 3, i, ( spmm * m_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 * m_spinorRest[i] ) / sqmt2 );
        R.set( 1, i, ( spp * m_spinorRest[i] ) / sqmt2 );
        R.set( 2, i, ( spm * m_spinorRest[i] ) / sqmt2 );
        R.set( 3, i, ( spmm * m_spinorRest[i] ) / sqmt2 );
    }
 
    return R;
}