EvtBTo3piCP.cpp

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#include "EvtGenModels/EvtBTo3piCP.hh"
 
#include "EvtGenBase/EvtCPUtil.hh"
#include "EvtGenBase/EvtConst.hh"
#include "EvtGenBase/EvtId.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtParticle.hh"
#include "EvtGenBase/EvtReport.hh"
 
#include <stdlib.h>
#include <string>
 
std::string EvtBTo3piCP::getName() const
{
    return "BTO3PI_CP";
}
 
EvtBTo3piCP* EvtBTo3piCP::clone() const
{
    return new EvtBTo3piCP;
}
 
void EvtBTo3piCP::init()
{
    // check that there are 2 arguments
    checkNArg( 2 );
    checkNDaug( 3 );
 
    checkSpinParent( EvtSpinType::SCALAR );
 
    checkSpinDaughter( 0, EvtSpinType::SCALAR );
    checkSpinDaughter( 1, EvtSpinType::SCALAR );
    checkSpinDaughter( 2, EvtSpinType::SCALAR );
}
 
void EvtBTo3piCP::initProbMax()
{
    // perform common blocks initialization before
    // first use
    double alpha = getArg( 1 );
    int iset;
 
    iset = 10000;
 
    EvtVector4R p4piplus, p4piminus, p4gamm1, p4gamm2;
 
    double realA, imgA, realbarA, imgbarA;
 
    m_generator.Evt3pi( alpha, iset, p4piplus, p4piminus, p4gamm1, p4gamm2,
                        realA, imgA, realbarA, imgbarA );
 
    setProbMax( 1.5 );
}
 
void EvtBTo3piCP::decay( EvtParticle* p )
{
    //added by Lange Jan4,2000
    static const EvtId B0 = EvtPDL::getId( "B0" );
    static const EvtId B0B = EvtPDL::getId( "anti-B0" );
 
    double t;
    EvtId other_b;
 
    EvtCPUtil::getInstance()->OtherB( p, t, other_b, 0.5 );
 
    EvtParticle *pip, *pim, *pi0;
 
    p->makeDaughters( getNDaug(), getDaugs() );
 
    //  p->init_daug(SCALAR,&pip,SCALAR,&pim,SCALAR,&pi0);
    pip = p->getDaug( 0 );
    pim = p->getDaug( 1 );
    pi0 = p->getDaug( 2 );
 
    EvtVector4R p4[3];
 
    double dm = getArg( 0 );
    double alpha = getArg( 1 );
    int iset;
 
    iset = 0;
 
    EvtVector4R p4piplus, p4piminus, p4gamm1, p4gamm2;
 
    double realA, imgA, realbarA, imgbarA;
 
    m_generator.Evt3pi( alpha, iset, p4[0], p4[1], p4gamm1, p4gamm2, realA,
                        imgA, realbarA, imgbarA );
 
    p4[2] = p4gamm1 + p4gamm2;
 
    if ( pip->getId() == EvtPDL::getId( "pi+" ) ) {
        pip->init( getDaug( 0 ), p4[0] );
        pim->init( getDaug( 1 ), p4[1] );
    } else {
        pip->init( getDaug( 0 ), p4[1] );
        pim->init( getDaug( 1 ), p4[0] );
    }
 
    pi0->init( getDaug( 2 ), p4[2] );
 
    EvtComplex amp;
 
    EvtComplex A( realA, imgA );
    EvtComplex Abar( realbarA, imgbarA );
 
    if ( other_b == B0B ) {
        amp = A * cos( dm * t / ( 2 * EvtConst::c ) ) +
              EvtComplex( 0., 1. ) * Abar * sin( dm * t / ( 2 * EvtConst::c ) );
    }
    if ( other_b == B0 ) {
        amp = Abar * cos( dm * t / ( 2 * EvtConst::c ) ) +
              EvtComplex( 0., 1. ) * A * sin( dm * t / ( 2 * EvtConst::c ) );
    }
 
    vertex( amp );
 
    return;
}