EvtBtoXsEtap.cpp

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#include "EvtGenModels/EvtBtoXsEtap.hh"

#include "EvtGenBase/EvtConst.hh"
#include "EvtGenBase/EvtGenKine.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtParticle.hh"
#include "EvtGenBase/EvtPatches.hh"
#include "EvtGenBase/EvtRandom.hh"
#include "EvtGenBase/EvtReport.hh"

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

std::string EvtBtoXsEtap::getName()
{
    return "BTOXSETAP";
}

EvtDecayBase* EvtBtoXsEtap::clone()
{
    return new EvtBtoXsEtap;
}

void EvtBtoXsEtap::init()
{
    // check that there are no arguments

    checkNArg( 0 );
}

void EvtBtoXsEtap::initProbMax()
{
    noProbMax();
}

void EvtBtoXsEtap::decay( EvtParticle* p )
{
    // useless
    //  if ( p->getNDaug() != 0 ) {
    //  //Will end up here because maxrate multiplies by 1.2
    //  EvtGenReport(EVTGEN_DEBUG,"EvtGen") << "In EvtBtoXsEtap: X_s daughters should not be here!"<<endl;
    //  return;
    //}

    double m_b;
    int i;
    p->makeDaughters( getNDaug(), getDaugs() );
    EvtParticle* pdaug[MAX_DAUG];

    for ( i = 0; i < getNDaug(); i++ ) {
        pdaug[i] = p->getDaug( i );
    }

    static EvtVector4R p4[MAX_DAUG];
    static double mass[MAX_DAUG];

    m_b = p->mass();

    // Prepare for phase space routine.

    mass[1] = EvtPDL::getMass( getDaug( 1 ) );

    double xbox, ybox, min, max, hichfit;
    min = 0.493;
    max = 4.3;
    const double TwoPi = EvtConst::twoPi;
    int Xscode = EvtPDL::getStdHep( getDaug( 0 ) );

    // A five parameters fit, the shape is taken from Atwood & Soni

    //  double par[18];
    double par[6];
    if ( ( Xscode == 30343 ) || ( Xscode == -30343 ) || ( Xscode == 30353 ) ||
         ( Xscode == -30353 ) ) {    // Xsu or Xsd
        min = 0.6373;                //  Just above K pi threshold for Xsd/u
        //min=0.6333; //  K pi threshold for neutral Xsd
        //    par[0]=-2057.2380371094;
        par[0] = 2.36816;
        //    par[1]=2502.2556152344;
        par[1] = 0.62325725;
        //    par[2]=1151.5632324219;
        par[2] = 2.2;
        //    par[3]=0.82431584596634;
        par[3] = -0.2109375;
        //    par[4]=-4110.5234375000;
        par[4] = 2.7;
        //    par[5]=8445.6757812500;
        par[5] = 0.54;
        //    par[6]=-3034.1894531250;
        //    par[7]=1.1557708978653;
        //    par[8]=1765.9311523438;
        //    par[9]=1.3730158805847;
        //    par[10]=0.51371538639069;
        //    par[11]=2.0056934356689;
        //    par[12]=37144.097656250;
        //    par[13]=-50296.781250000;
        //    par[14]=27319.095703125;
        //    par[15]=-7408.0678710938;
        //    par[16]=1000.8093261719;
        //    par[17]=-53.834449768066;
    } else {
        EvtGenReport( EVTGEN_DEBUG, "EvtGen" )
            << "In EvtBtoXsEtap: Particle with id " << Xscode
            << " is not a Xsd/u particle" << endl;
        return;
    }

    double boxheight = par[5];
    double boxwidth = max - min;

    mass[0] = 0.0;
    while ( ( mass[0] > max ) || ( mass[0] < min ) ) {
        xbox = EvtRandom::Flat( boxwidth ) + min;
        ybox = EvtRandom::Flat( boxheight );
        if ( xbox < par[2] ) {
            hichfit = ( 1 / sqrt( TwoPi * par[1] ) ) *
                      exp( -0.5 * pow( ( xbox - par[0] ) / par[1], 2 ) );
            //      alifit=par[0]+par[1]*xbox+par[2]*pow(xbox,2);
            //    } else if (xbox<par[7]) {
            //      alifit=par[4]+par[5]*xbox+par[6]*pow(xbox,2);
            //    } else if (xbox<par[11]) {
            //      alifit=par[8]*exp(-0.5*pow((xbox-par[9])/par[10],2));
        } else {
            hichfit = par[3] * pow( ( xbox - par[4] ), 2 ) + par[5];
            //      alifit=par[12]+par[13]*xbox+par[14]*pow(xbox,2)+par[15]*pow(xbox,3)+par[16]*pow(xbox,4)+par[17]*pow(xbox,5);
        }
        if ( ybox > hichfit ) {
            mass[0] = 0.0;
        } else {
            mass[0] = xbox;
        }
    }

    // debug stuff:  EvtGenReport(EVTGEN_INFO,"EvtGen") << "Xscode " << Xscode << " daughter 1 mass " << mass[0] << " daughter 2 mass " << mass[1] << endl;

    EvtGenKine::PhaseSpace( getNDaug(), mass, p4, m_b );

    for ( i = 0; i < getNDaug(); i++ ) {
        pdaug[i]->init( getDaugs()[i], p4[i] );
    }

    return;
}