EvtLb2plnuLCSRFF.cpp

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#include "EvtGenModels/EvtLb2plnuLCSRFF.hh"

#include "EvtGenBase/EvtConst.hh"
#include "EvtGenBase/EvtId.hh"
#include "EvtGenBase/EvtIdSet.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtPatches.hh"
#include "EvtGenBase/EvtReport.hh"

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

void EvtLb2plnuLCSRFF::getdiracff( EvtId parent, EvtId daught, double q2,
                                   double /* mass */, double* f1, double* f2,
                                   double* f3, double* g1, double* g2, double* g3 )
{
    // Define Event IDs for Lb and p
    static EvtId LAMB = EvtPDL::getId( "Lambda_b0" );
    static EvtId LAMBB = EvtPDL::getId( "anti-Lambda_b0" );
    static EvtId PRO = EvtPDL::getId( "p+" );
    static EvtId PROB = EvtPDL::getId( "anti-p-" );

    if ( ( parent == LAMB && daught == PRO ) ||
         ( parent == LAMBB && daught == PROB ) ) {
        // Calculate Lb->p form factors based on LCSR predictions
        // Predictions taken from A. Khodjamirian, C. Klein, T. Mannel and Y.-M. Wang, arXiv.1108.2971 (2011)

        double MLamB = EvtPDL::getMass( parent );
        double MPro = EvtPDL::getMass( daught );

        double tplus = ( MLamB + MPro ) * ( MLamB + MPro );
        double tminus = ( MLamB - MPro ) * ( MLamB - MPro );
        double t0 = tplus - sqrt( tplus - tminus ) * sqrt( tplus + 6 );
        double z = ( sqrt( tplus - q2 ) - sqrt( tplus - t0 ) ) /
                   ( sqrt( tplus - q2 ) + sqrt( tplus - t0 ) );
        double z0 = ( sqrt( tplus ) - sqrt( tplus - t0 ) ) /
                    ( sqrt( tplus ) + sqrt( tplus - t0 ) );

        // FF parameters
        double f10 = 0.14;
        double bf1 = -1.49;
        double f20 = -0.054;
        double bf2 = -14.0;
        double g10 = 0.14;
        double bg1 = -4.05;
        double g20 = -0.028;
        double bg2 = -20.2;

        //FF paramterisation
        double F1 = ( f10 / ( 1.0 - q2 / ( 5.325 * 5.325 ) ) ) *
                    ( 1.0 + bf1 * ( z - z0 ) );
        double F2 = ( f20 / ( 1.0 - q2 / ( 5.325 * 5.325 ) ) ) *
                    ( 1.0 + bf2 * ( z - z0 ) );
        double G1 = ( g10 / ( 1.0 - q2 / ( 5.723 * 5.723 ) ) ) *
                    ( 1.0 + bg1 * ( z - z0 ) );
        double G2 = ( g20 / ( 1.0 - q2 / ( 5.723 * 5.723 ) ) ) *
                    ( 1.0 + bg2 * ( z - z0 ) );

        *f1 = F1 - ( MLamB + MPro ) * F2 / MLamB;
        *f2 = F2;
        *f3 = MPro * ( F2 ) / MLamB;
        *g1 = G1 - ( MLamB - MPro ) * G2 / MLamB;
        *g2 = -G2;
        *g3 = -MPro * G2 / MLamB;

    } else {
        EvtGenReport( EVTGEN_ERROR, "EvtGen" )
            << "Only Lb -> p transitions allowed in EvtLb2plnuLCSRFF.\n";
        ::abort();
    }

    return;
}

void EvtLb2plnuLCSRFF::getraritaff( EvtId, EvtId, double, double, double*,
                                    double*, double*, double*, double*, double*,
                                    double*, double* )
{
    EvtGenReport( EVTGEN_ERROR, "EvtGen" )
        << "Not implemented :getraritaff in EvtLb2plnuLCSRFF.\n";
    ::abort();
}

void EvtLb2plnuLCSRFF::getscalarff( EvtId, EvtId, double, double, double*,
                                    double* )
{
    EvtGenReport( EVTGEN_ERROR, "EvtGen" )
        << "Not implemented :getscalarff in EvtLb2plnuLCSRFF.\n";
    ::abort();
}

void EvtLb2plnuLCSRFF::getvectorff( EvtId, EvtId, double, double, double*,
                                    double*, double*, double* )
{
    EvtGenReport( EVTGEN_ERROR, "EvtGen" )
        << "Not implemented :getvectorff in EvtLb2plnuLCSRFF.\n";
    ::abort();
}

void EvtLb2plnuLCSRFF::gettensorff( EvtId, EvtId, double, double, double*,
                                    double*, double*, double* )
{
    EvtGenReport( EVTGEN_ERROR, "EvtGen" )
        << "Not implemented :gettensorff in EvtLb2plnuLCSRFF.\n";
    ::abort();
}

void EvtLb2plnuLCSRFF::getbaryonff( EvtId, EvtId, double, double, double*,
                                    double*, double*, double* )
{
    EvtGenReport( EVTGEN_ERROR, "EvtGen" )
        << "Not implemented :getbaryonff in EvtLb2plnuLCSRFF.\n";
    ::abort();
}