EvtSVSNONCPEIGEN.cpp

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#include "EvtGenModels/EvtSVSNONCPEIGEN.hh"
 
#include "EvtGenBase/EvtCPUtil.hh"
#include "EvtGenBase/EvtConst.hh"
#include "EvtGenBase/EvtGenKine.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtParticle.hh"
#include "EvtGenBase/EvtRandom.hh"
#include "EvtGenBase/EvtReport.hh"
#include "EvtGenBase/EvtVector4C.hh"
 
#include <stdlib.h>
#include <string>
 
std::string EvtSVSNONCPEIGEN::getName() const
{
    return "SVS_NONCPEIGEN";
}
 
EvtDecayBase* EvtSVSNONCPEIGEN::clone() const
{
    return new EvtSVSNONCPEIGEN;
}
 
void EvtSVSNONCPEIGEN::init()
{
    // check that there are 11 arguments
    checkNArg( 11, 7 );
    checkNDaug( 2 );
 
    checkSpinDaughter( 0, EvtSpinType::VECTOR );
    checkSpinDaughter( 1, EvtSpinType::SCALAR );
 
    m_dm = getArg( 1 );
    m_phickm = 2 * getArg( 0 ) + getArg( 2 );
 
    m_A_f = EvtComplex( getArg( 3 ) * cos( getArg( 4 ) ),
                        getArg( 3 ) * sin( getArg( 4 ) ) );
    m_Abar_f = EvtComplex( getArg( 5 ) * cos( getArg( 6 ) ),
                           getArg( 5 ) * sin( getArg( 6 ) ) );
 
    m_A_fbar = m_Abar_f;
    m_Abar_fbar = m_A_f;
 
    if ( getNArg() == 11 ) {
        m_A_fbar = EvtComplex( getArg( 7 ) * cos( getArg( 8 ) ),
                               getArg( 7 ) * sin( getArg( 8 ) ) );
        m_Abar_fbar = EvtComplex( getArg( 9 ) * cos( getArg( 10 ) ),
                                  getArg( 9 ) * sin( getArg( 10 ) ) );
    }
}
 
void EvtSVSNONCPEIGEN::initProbMax()
{
    double theProbMax = abs( m_A_f ) * abs( m_A_f ) +
                        abs( m_Abar_f ) * abs( m_Abar_f ) +
                        abs( m_A_fbar ) * abs( m_A_fbar ) +
                        abs( m_Abar_fbar ) * abs( m_Abar_fbar );
 
    setProbMax( theProbMax );
}
 
void EvtSVSNONCPEIGEN::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;
    EvtId daugs[2];
 
    // MB: flip selects the final of the decay
    int flip = ( ( p->getId() == B0 ) ? 0 : 1 );
    daugs[0] = getDaug( 0 );
    daugs[1] = getDaug( 1 );
    p->initializePhaseSpace( 2, daugs );
 
    EvtCPUtil::getInstance()->OtherB( p, t, other_b, 0.5 );
 
    EvtComplex amp;
    double dmt2 = ( m_dm * t ) / ( 2 * EvtConst::c );
    EvtComplex ePlusIPhi( cos( m_phickm ), sin( m_phickm ) );
    EvtComplex eMinusIPhi( cos( -m_phickm ), -sin( m_phickm ) );
 
    // flip == 0 : D-rho+
    // flip == 1 : D+rho-
 
    if ( !flip ) {
        if ( other_b == B0B ) {
            // At t=0 we have a B0
            amp = cos( dmt2 ) * m_A_f +
                  eMinusIPhi * EvtComplex( 0.0, sin( dmt2 ) ) * m_Abar_f;
        }
        if ( other_b == B0 ) {
            // At t=0 we have a B0bar
            amp = ePlusIPhi * EvtComplex( 0.0, sin( dmt2 ) ) * m_A_f +
                  cos( dmt2 ) * m_Abar_f;
        }
    } else {
        if ( other_b == B0B ) {
            // At t=0 we have a B0
            amp = cos( dmt2 ) * m_A_fbar +
                  eMinusIPhi * EvtComplex( 0.0, sin( dmt2 ) ) * m_Abar_fbar;
        }
        if ( other_b == B0 ) {
            // At t=0 we have a B0bar
            amp = ePlusIPhi * EvtComplex( 0.0, sin( dmt2 ) ) * m_A_fbar +
                  cos( dmt2 ) * m_Abar_fbar;
        }
    }
 
    EvtParticle* v;
    v = p->getDaug( 0 );
 
    EvtVector4R momv = p->getDaug( 0 )->getP4();
    EvtVector4R moms = p->getDaug( 1 )->getP4();
    EvtVector4R p4_parent = momv + moms;
 
    double norm = momv.mass() / ( momv.d3mag() * p->mass() );
 
    vertex( 0, amp * norm * p4_parent * ( v->epsParent( 0 ) ) );
    vertex( 1, amp * norm * p4_parent * ( v->epsParent( 1 ) ) );
    vertex( 2, amp * norm * p4_parent * ( v->epsParent( 2 ) ) );
 
    return;
}