EvtSVPCP.cpp

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#include "EvtGenModels/EvtSVPCP.hh"

#include "EvtGenBase/EvtCPUtil.hh"
#include "EvtGenBase/EvtComplex.hh"
#include "EvtGenBase/EvtConst.hh"
#include "EvtGenBase/EvtGenKine.hh"
#include "EvtGenBase/EvtId.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtParticle.hh"
#include "EvtGenBase/EvtPatches.hh"
#include "EvtGenBase/EvtReport.hh"
#include "EvtGenBase/EvtTensor3C.hh"
#include "EvtGenBase/EvtTensor4C.hh"
#include "EvtGenBase/EvtVector4C.hh"
#include "EvtGenBase/EvtVector4R.hh"

#include <stdlib.h>
#include <string>

std::string EvtSVPCP::getName()
{
    return "SVP_CP";
}

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

void EvtSVPCP::initProbMax()
{
    setProbMax( 2 * ( getArg( 3 ) * getArg( 3 ) + getArg( 5 ) * getArg( 5 ) ) );
}

void EvtSVPCP::init()
{
    // check that there are 7 arguments
    checkNArg( 7 );
    checkNDaug( 2 );

    checkSpinParent( EvtSpinType::SCALAR );

    checkSpinDaughter( 0, EvtSpinType::VECTOR );
    checkSpinDaughter( 1, EvtSpinType::PHOTON );
}

void EvtSVPCP::decay( EvtParticle* p )
{
    static EvtId B0 = EvtPDL::getId( "B0" );
    static EvtId B0B = EvtPDL::getId( "anti-B0" );

    double t;
    EvtId other_b;

    EvtCPUtil::getInstance()->OtherB( p, t, other_b, 0.5 );

    EvtComplex G1P, G1M, G1_T_even, G1_T_odd;

    double norm = getArg( 3 ) * getArg( 3 ) + getArg( 5 ) * getArg( 5 );

    G1P = EvtComplex( getArg( 3 ) * cos( getArg( 4 ) ) / norm,
                      getArg( 3 ) * sin( getArg( 4 ) ) / norm );
    G1M = EvtComplex( getArg( 5 ) * cos( getArg( 6 ) ) / norm,
                      getArg( 5 ) * sin( getArg( 6 ) ) / norm );

    G1_T_even = ( G1P + G1M ) / sqrt( 2.0 );
    G1_T_odd = ( G1P - G1M ) / sqrt( 2.0 );

    EvtComplex lambda_km = EvtComplex( cos( -2 * getArg( 0 ) ),
                                       sin( -2 * getArg( 0 ) ) );

    double cdmt = cos( getArg( 1 ) * t / ( 2 * EvtConst::c ) );
    double sdmt = sin( getArg( 1 ) * t / ( 2 * EvtConst::c ) );

    EvtComplex cG1_T_even, cG1_T_odd;

    if ( other_b == B0B ) {
        cG1_T_even = G1_T_even *
                     ( cdmt + lambda_km * EvtComplex( 0.0, getArg( 2 ) * sdmt ) );
        cG1_T_odd = G1_T_odd *
                    ( cdmt - lambda_km * EvtComplex( 0.0, getArg( 2 ) * sdmt ) );
    }
    if ( other_b == B0 ) {
        cG1_T_even = G1_T_even *
                     ( cdmt + ( 1.0 / lambda_km ) *
                                  EvtComplex( 0.0, getArg( 2 ) * sdmt ) );
        cG1_T_odd = -G1_T_odd *
                    ( cdmt - ( 1.0 / lambda_km ) *
                                 EvtComplex( 0.0, getArg( 2 ) * sdmt ) );
    }

    EvtComplex hp, hm, h0;

    // This part is adopted from EvtSVVHel and since there is
    // a photon that can not have helicity 0 this is put in by
    // setting the h0 amplitude to 0.
    hm = ( cG1_T_even - cG1_T_odd ) / sqrt( 2.0 );
    hp = ( cG1_T_even + cG1_T_odd ) / sqrt( 2.0 );
    h0 = EvtComplex( 0.0, 0.0 );

    EvtParticle *v1, *ph;

    p->initializePhaseSpace( getNDaug(), getDaugs() );
    v1 = p->getDaug( 0 );
    ph = p->getDaug( 1 );
    EvtVector4R momv1 = v1->getP4();
    EvtVector4R momph = ph->getP4();

    EvtTensor4C d, g;

    g.setdiag( 1.0, -1.0, -1.0, -1.0 );

    EvtVector4R v, vp;

    v = momv1 / momv1.d3mag();
    vp = ( momv1 + momph ) / ( momv1 + momph ).mass();

    d = ( ( 1.0 / sqrt( 3.0 ) ) * ( h0 - ( hp + hm ) ) * ( -1.0 / sqrt( 3.0 ) ) ) *
            g +
        ( ( 1.0 / sqrt( 2.0 ) ) * ( hp - hm ) * EvtComplex( 0.0, 1.0 ) *
          ( sqrt( 1.0 / 2.0 ) ) ) *
            dual( EvtGenFunctions::directProd( v, vp ) ) +
        ( sqrt( 2.0 / 3.0 ) * ( h0 + 0.5 * ( hp + hm ) ) * sqrt( 3.0 / 2.0 ) ) *
            ( EvtGenFunctions::directProd( v, v ) + ( 1.0 / 3.0 ) * g );

    EvtVector4C ep0, ep1, ep2;

    ep0 = d.cont1( v1->eps( 0 ).conj() );
    ep1 = d.cont1( v1->eps( 1 ).conj() );
    ep2 = d.cont1( v1->eps( 2 ).conj() );

    EvtVector4C ep20, ep21, ep22;

    ep20 = ph->epsParentPhoton( 0 ).conj();
    ep21 = ph->epsParentPhoton( 1 ).conj();

    vertex( 0, 0, ep0 * ep20 );
    vertex( 0, 1, ep0 * ep21 );

    vertex( 1, 0, ep1 * ep20 );
    vertex( 1, 1, ep1 * ep21 );

    vertex( 2, 0, ep2 * ep20 );
    vertex( 2, 1, ep2 * ep21 );

    return;
}

std::string EvtSVPCP::getParamName( int i )
{
    switch ( i ) {
        case 0:
            return "weakPhase";
        case 1:
            return "deltaM";
        case 2:
            return "finalStateCP";
        case 3:
            return "Af";
        case 4:
            return "AfPhase";
        case 5:
            return "Abarf";
        case 6:
            return "AbarfPhase";
        default:
            return "";
    }
}

std::string EvtSVPCP::getParamDefault( int i )
{
    switch ( i ) {
        case 3:
            return "1.0";
        case 4:
            return "0.0";
        case 5:
            return "1.0";
        case 6:
            return "0.0";
        default:
            return "";
    }
}