EvtDecayAmp.cpp

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#include "EvtGenBase/EvtDecayAmp.hh"
 
#include "EvtGenBase/EvtAmp.hh"
#include "EvtGenBase/EvtDecayBase.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtParticle.hh"
#include "EvtGenBase/EvtRadCorr.hh"
#include "EvtGenBase/EvtRandom.hh"
#include "EvtGenBase/EvtReport.hh"
using std::endl;
 
void EvtDecayAmp::makeDecay( EvtParticle* p, bool recursive )
{
    //original default value
    int ntimes = 10000;
 
    int more;
 
    EvtSpinDensity rho;
    double prob, prob_max;
 
    m_amp2.init( p->getId(), getNDaug(), getDaugs() );
 
    do {
        m_daugsDecayedByParentModel = false;
        m_weight = 1.0;
        decay( p );
 
        rho = m_amp2.getSpinDensity();
 
        prob = p->getSpinDensityForward().normalizedProb( rho );
 
        if ( prob < 0.0 ) {
            EvtGenReport( EVTGEN_ERROR, "EvtGen" )
                << "Negative prob:" << p->getId().getId() << " "
                << p->getChannel() << endl;
 
            EvtGenReport( EVTGEN_ERROR, "EvtGen" ) << "rho_forward:" << endl;
            EvtGenReport( EVTGEN_ERROR, "EvtGen" ) << p->getSpinDensityForward();
            EvtGenReport( EVTGEN_ERROR, "EvtGen" ) << "rho decay:" << endl;
            EvtGenReport( EVTGEN_ERROR, "EvtGen" ) << rho << endl;
        }
 
        if ( prob != prob ) {
            EvtGenReport( EVTGEN_DEBUG, "EvtGen" )
                << "Forward density matrix:" << endl;
            EvtGenReport( EVTGEN_DEBUG, "EvtGen" ) << p->getSpinDensityForward();
 
            EvtGenReport( EVTGEN_DEBUG, "EvtGen" )
                << "Decay density matrix:" << endl;
            EvtGenReport( EVTGEN_DEBUG, "EvtGen" ) << rho;
 
            EvtGenReport( EVTGEN_DEBUG, "EvtGen" ) << "prob:" << prob << endl;
 
            EvtGenReport( EVTGEN_DEBUG, "EvtGen" )
                << "Particle:" << EvtPDL::name( p->getId() ).c_str() << endl;
            EvtGenReport( EVTGEN_DEBUG, "EvtGen" )
                << "channel        :" << p->getChannel() << endl;
            EvtGenReport( EVTGEN_DEBUG, "EvtGen" )
                << "Momentum:" << p->getP4() << " " << p->mass() << endl;
            if ( p->getParent() != nullptr ) {
                EvtGenReport( EVTGEN_DEBUG, "EvtGen" )
                    << "parent:"
                    << EvtPDL::name( p->getParent()->getId() ).c_str() << endl;
                EvtGenReport( EVTGEN_DEBUG, "EvtGen" )
                    << "parent channel        :" << p->getParent()->getChannel()
                    << endl;
 
                EvtGenReport( EVTGEN_DEBUG, "EvtGen" ) << "parent daughters  :";
                for ( size_t i = 0; i < p->getParent()->getNDaug(); i++ ) {
                    EvtGenReport( EVTGEN_DEBUG, "" )
                        << EvtPDL::name( p->getParent()->getDaug( i )->getId() )
                               .c_str()
                        << " ";
                }
                EvtGenReport( EVTGEN_DEBUG, "" ) << endl;
 
                EvtGenReport( EVTGEN_DEBUG, "EvtGen" ) << "daughters  :";
                for ( size_t i = 0; i < p->getNDaug(); i++ ) {
                    EvtGenReport( EVTGEN_DEBUG, "" )
                        << EvtPDL::name( p->getDaug( i )->getId() ).c_str()
                        << " ";
                }
                EvtGenReport( EVTGEN_DEBUG, "" ) << endl;
 
                EvtGenReport( EVTGEN_DEBUG, "EvtGen" )
                    << "daughter momenta  :" << endl;
                ;
                for ( size_t i = 0; i < p->getNDaug(); i++ ) {
                    EvtGenReport( EVTGEN_DEBUG, "" )
                        << p->getDaug( i )->getP4() << " "
                        << p->getDaug( i )->mass();
                    EvtGenReport( EVTGEN_DEBUG, "" ) << endl;
                }
            }
        }
 
        prob /= m_weight;
 
        prob_max = getProbMax( prob );
        p->setDecayProb( prob / prob_max );
 
        more = prob < EvtRandom::Flat( prob_max );
 
        ntimes--;
 
    } while ( ntimes && more );
 
    if ( ntimes == 0 ) {
        EvtGenReport( EVTGEN_DEBUG, "EvtGen" )
            << "Tried accept/reject: 10000"
            << " times, and rejected all the times!" << endl;
 
        EvtGenReport( EVTGEN_DEBUG, "EvtGen" )
            << p->getSpinDensityForward() << endl;
        EvtGenReport( EVTGEN_DEBUG, "EvtGen" )
            << "Is therefore accepting the last event!" << endl;
        EvtGenReport( EVTGEN_DEBUG, "EvtGen" )
            << "Decay of particle:" << EvtPDL::name( p->getId() ).c_str()
            << "(channel:" << p->getChannel() << ") with mass " << p->mass()
            << endl;
 
        for ( size_t ii = 0; ii < p->getNDaug(); ii++ ) {
            EvtGenReport( EVTGEN_DEBUG, "EvtGen" )
                << "Daughter " << ii << ":"
                << EvtPDL::name( p->getDaug( ii )->getId() ).c_str()
                << " with mass " << p->getDaug( ii )->mass() << endl;
        }
    }
 
    EvtSpinDensity rho_list[10];
 
    rho_list[0] = p->getSpinDensityForward();
 
    EvtAmp ampcont;
 
    if ( m_amp2.m_pstates != 1 ) {
        ampcont = m_amp2.contract( 0, p->getSpinDensityForward() );
    } else {
        ampcont = m_amp2;
    }
 
    // it may be that the parent decay model has already
    // done the decay - this should be rare and the
    // model better know what it is doing..
 
    if ( !daugsDecayedByParentModel() ) {
        if ( recursive ) {
            for ( size_t i = 0; i < p->getNDaug(); i++ ) {
                rho.setDim( m_amp2.m_dstates[i] );
 
                if ( m_amp2.m_dstates[i] == 1 ) {
                    rho.set( 0, 0, EvtComplex( 1.0, 0.0 ) );
                } else {
                    rho = ampcont.contract( m_amp2.m_dnontrivial[i], m_amp2 );
                }
 
                if ( !rho.check() ) {
                    EvtGenReport( EVTGEN_ERROR, "EvtGen" )
                        << "-------start error-------" << endl;
                    EvtGenReport( EVTGEN_ERROR, "EvtGen" )
                        << "forward rho failed Check:"
                        << EvtPDL::name( p->getId() ).c_str() << " "
                        << p->getChannel() << " " << i << endl;
 
                    p->printTree();
 
                    for ( size_t idaug = 0; idaug < p->getNDaug(); idaug++ ) {
                        EvtParticle* daughter = p->getDaug( idaug );
                        if ( daughter != nullptr ) {
                            daughter->printTree();
                        }
                    }
 
                    EvtParticle* pParent = p->getParent();
                    if ( pParent != nullptr ) {
                        EvtGenReport( EVTGEN_ERROR, "EvtGen" )
                            << "Parent:"
                            << EvtPDL::name( pParent->getId() ).c_str() << endl;
 
                        EvtParticle* grandParent = pParent->getParent();
 
                        if ( grandParent != nullptr ) {
                            EvtGenReport( EVTGEN_ERROR, "EvtGen" )
                                << "GrandParent:"
                                << EvtPDL::name( grandParent->getId() ).c_str()
                                << endl;
                        }
                    }
 
                    EvtGenReport( EVTGEN_ERROR, "EvtGen" )
                        << " EvtSpinDensity rho: " << rho;
 
                    m_amp2.dump();
 
                    for ( size_t ii = 0; ii < i + 1; ii++ ) {
                        EvtGenReport( EVTGEN_ERROR, "EvtGen" )
                            << "rho_list[" << ii << "] = " << rho_list[ii];
                    }
 
                    EvtGenReport( EVTGEN_ERROR, "EvtGen" )
                        << "-------Done with error-------" << endl;
                }
 
                p->getDaug( i )->setSpinDensityForward( rho );
                p->getDaug( i )->decay();
 
                rho_list[i + 1] = p->getDaug( i )->getSpinDensityBackward();
 
                if ( m_amp2.m_dstates[i] != 1 ) {
                    ampcont = ampcont.contract( m_amp2.m_dnontrivial[i],
                                                rho_list[i + 1] );
                }
            }
 
            p->setSpinDensityBackward( m_amp2.getBackwardSpinDensity( rho_list ) );
 
            if ( !p->getSpinDensityBackward().check() ) {
                EvtGenReport( EVTGEN_ERROR, "EvtGen" )
                    << "rho_backward failed Check" << p->getId().getId() << " "
                    << p->getChannel() << endl;
 
                EvtGenReport( EVTGEN_ERROR, "EvtGen" )
                    << p->getSpinDensityBackward();
            }
        }
    }
 
    if ( ( getFSR() || EvtRadCorr::alwaysRadCorr() ) &&
         !EvtRadCorr::neverRadCorr() ) {
        int n_daug_orig = p->getNDaug();
        EvtRadCorr::doRadCorr( p );
        int n_daug_new = p->getNDaug();
        for ( int i = n_daug_orig; i < n_daug_new; i++ ) {
            p->getDaug( i )->decay();
        }
    }
}