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EvtSemiLeptonicBaryonAmp.cpp
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EvtSemiLeptonicBaryonAmp.cpp
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/***********************************************************************
* Copyright 1998-2020 CERN for the benefit of the EvtGen authors *
* *
* This file is part of EvtGen. *
* *
* EvtGen is free software: you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation, either version 3 of the License, or *
* (at your option) any later version. *
* *
* EvtGen is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with EvtGen. If not, see <https://www.gnu.org/licenses/>. *
***********************************************************************/
#include "EvtGenBase/EvtSemiLeptonicBaryonAmp.hh"
#include "EvtGenBase/EvtAmp.hh"
#include "EvtGenBase/EvtDiracParticle.hh"
#include "EvtGenBase/EvtDiracSpinor.hh"
#include "EvtGenBase/EvtGammaMatrix.hh"
#include "EvtGenBase/EvtGenKine.hh"
#include "EvtGenBase/EvtId.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtParticle.hh"
#include "EvtGenBase/EvtPatches.hh"
#include "EvtGenBase/EvtRaritaSchwinger.hh"
#include "EvtGenBase/EvtReport.hh"
#include "EvtGenBase/EvtSemiLeptonicFF.hh"
#include "EvtGenBase/EvtTensor4C.hh"
#include "EvtGenBase/EvtVector4C.hh"
#include <stdlib.h>
using std::endl;
void EvtSemiLeptonicBaryonAmp::CalcAmp( EvtParticle* parent, EvtAmp& amp,
EvtSemiLeptonicFF* FormFactors )
{
static EvtId EM = EvtPDL::getId( "e-" );
static EvtId MUM = EvtPDL::getId( "mu-" );
static EvtId TAUM = EvtPDL::getId( "tau-" );
static EvtId EP = EvtPDL::getId( "e+" );
static EvtId MUP = EvtPDL::getId( "mu+" );
static EvtId TAUP = EvtPDL::getId( "tau+" );
//Add the lepton and neutrino 4 momenta to find q2
EvtVector4R q = parent->getDaug( 1 )->getP4() + parent->getDaug( 2 )->getP4();
double q2 = ( q.mass2() );
double f1v, f1a, f2v, f2a;
double m_meson = parent->getDaug( 0 )->mass();
FormFactors->getbaryonff( parent->getId(), parent->getDaug( 0 )->getId(),
q2, m_meson, &f1v, &f1a, &f2v, &f2a );
EvtVector4R p4b;
p4b.set( parent->mass(), 0.0, 0.0, 0.0 );
EvtVector4C temp_00_term1;
EvtVector4C temp_00_term2;
EvtVector4C temp_01_term1;
EvtVector4C temp_01_term2;
EvtVector4C temp_10_term1;
EvtVector4C temp_10_term2;
EvtVector4C temp_11_term1;
EvtVector4C temp_11_term2;
EvtDiracSpinor p0 = parent->sp( 0 );
EvtDiracSpinor p1 = parent->sp( 1 );
EvtDiracSpinor d0 = parent->getDaug( 0 )->spParent( 0 );
EvtDiracSpinor d1 = parent->getDaug( 0 )->spParent( 1 );
temp_00_term1.set( 0, f1v * ( d0 * ( EvtGammaMatrix::g0() * p0 ) ) );
temp_00_term2.set(
0,
f1a * ( d0 * ( ( EvtGammaMatrix::g0() * EvtGammaMatrix::g5() ) * p0 ) ) );
temp_01_term1.set( 0, f1v * ( d0 * ( EvtGammaMatrix::g0() * p1 ) ) );
temp_01_term2.set(
0,
f1a * ( d0 * ( ( EvtGammaMatrix::g0() * EvtGammaMatrix::g5() ) * p1 ) ) );
temp_10_term1.set( 0, f1v * ( d1 * ( EvtGammaMatrix::g0() * p0 ) ) );
temp_10_term2.set(
0,
f1a * ( d1 * ( ( EvtGammaMatrix::g0() * EvtGammaMatrix::g5() ) * p0 ) ) );
temp_11_term1.set( 0, f1v * ( d1 * ( EvtGammaMatrix::g0() * p1 ) ) );
temp_11_term2.set(
0,
f1a * ( d1 * ( ( EvtGammaMatrix::g0() * EvtGammaMatrix::g5() ) * p1 ) ) );
temp_00_term1.set( 1, f1v * ( d0 * ( EvtGammaMatrix::g1() * p0 ) ) );
temp_00_term2.set(
1,
f1a * ( d0 * ( ( EvtGammaMatrix::g1() * EvtGammaMatrix::g5() ) * p0 ) ) );
temp_01_term1.set( 1, f1v * ( d0 * ( EvtGammaMatrix::g1() * p1 ) ) );
temp_01_term2.set(
1,
f1a * ( d0 * ( ( EvtGammaMatrix::g1() * EvtGammaMatrix::g5() ) * p1 ) ) );
temp_10_term1.set( 1, f1v * ( d1 * ( EvtGammaMatrix::g1() * p0 ) ) );
temp_10_term2.set(
1,
f1a * ( d1 * ( ( EvtGammaMatrix::g1() * EvtGammaMatrix::g5() ) * p0 ) ) );
temp_11_term1.set( 1, f1v * ( d1 * ( EvtGammaMatrix::g1() * p1 ) ) );
temp_11_term2.set(
1,
f1a * ( d1 * ( ( EvtGammaMatrix::g1() * EvtGammaMatrix::g5() ) * p1 ) ) );
temp_00_term1.set( 2, f1v * ( d0 * ( EvtGammaMatrix::g2() * p0 ) ) );
temp_00_term2.set(
2,
f1a * ( d0 * ( ( EvtGammaMatrix::g2() * EvtGammaMatrix::g5() ) * p0 ) ) );
temp_01_term1.set( 2, f1v * ( d0 * ( EvtGammaMatrix::g2() * p1 ) ) );
temp_01_term2.set(
2,
f1a * ( d0 * ( ( EvtGammaMatrix::g2() * EvtGammaMatrix::g5() ) * p1 ) ) );
temp_10_term1.set( 2, f1v * ( d1 * ( EvtGammaMatrix::g2() * p0 ) ) );
temp_10_term2.set(
2,
f1a * ( d1 * ( ( EvtGammaMatrix::g2() * EvtGammaMatrix::g5() ) * p0 ) ) );
temp_11_term1.set( 2, f1v * ( d1 * ( EvtGammaMatrix::g2() * p1 ) ) );
temp_11_term2.set(
2,
f1a * ( d1 * ( ( EvtGammaMatrix::g2() * EvtGammaMatrix::g5() ) * p1 ) ) );
temp_00_term1.set( 3, f1v * ( d0 * ( EvtGammaMatrix::g3() * p0 ) ) );
temp_00_term2.set(
3,
f1a * ( d0 * ( ( EvtGammaMatrix::g3() * EvtGammaMatrix::g5() ) * p0 ) ) );
temp_01_term1.set( 3, f1v * ( d0 * ( EvtGammaMatrix::g3() * p1 ) ) );
temp_01_term2.set(
3,
f1a * ( d0 * ( ( EvtGammaMatrix::g3() * EvtGammaMatrix::g5() ) * p1 ) ) );
temp_10_term1.set( 3, f1v * ( d1 * ( EvtGammaMatrix::g3() * p0 ) ) );
temp_10_term2.set(
3,
f1a * ( d1 * ( ( EvtGammaMatrix::g3() * EvtGammaMatrix::g5() ) * p0 ) ) );
temp_11_term1.set( 3, f1v * ( d1 * ( EvtGammaMatrix::g3() * p1 ) ) );
temp_11_term2.set(
3,
f1a * ( d1 * ( ( EvtGammaMatrix::g3() * EvtGammaMatrix::g5() ) * p1 ) ) );
EvtVector4C l1, l2;
EvtId l_num = parent->getDaug( 1 )->getId();
if ( l_num == EM || l_num == MUM || l_num == TAUM ) {
l1 = EvtLeptonVACurrent( parent->getDaug( 1 )->spParent( 0 ),
parent->getDaug( 2 )->spParentNeutrino() );
l2 = EvtLeptonVACurrent( parent->getDaug( 1 )->spParent( 1 ),
parent->getDaug( 2 )->spParentNeutrino() );
} else {
if ( l_num == EP || l_num == MUP || l_num == TAUP ) {
l1 = EvtLeptonVACurrent( parent->getDaug( 2 )->spParentNeutrino(),
parent->getDaug( 1 )->spParent( 0 ) );
l2 = EvtLeptonVACurrent( parent->getDaug( 2 )->spParentNeutrino(),
parent->getDaug( 1 )->spParent( 1 ) );
} else {
EvtGenReport( EVTGEN_ERROR, "EvtGen" )
<< "Wrong lepton number" << endl;
}
}
amp.vertex( 0, 0, 0, l1.cont( temp_00_term1 + temp_00_term2 ) );
amp.vertex( 0, 0, 1, l2.cont( temp_00_term1 + temp_00_term2 ) );
amp.vertex( 0, 1, 0, l1.cont( temp_01_term1 + temp_01_term2 ) );
amp.vertex( 0, 1, 1, l2.cont( temp_01_term1 + temp_01_term2 ) );
amp.vertex( 1, 0, 0, l1.cont( temp_10_term1 + temp_10_term2 ) );
amp.vertex( 1, 0, 1, l2.cont( temp_10_term1 + temp_10_term2 ) );
amp.vertex( 1, 1, 0, l1.cont( temp_11_term1 + temp_11_term2 ) );
amp.vertex( 1, 1, 1, l2.cont( temp_11_term1 + temp_11_term2 ) );
return;
}
double EvtSemiLeptonicBaryonAmp::CalcMaxProb( EvtId parent, EvtId baryon,
EvtId lepton, EvtId nudaug,
EvtSemiLeptonicFF* FormFactors,
EvtComplex r00, EvtComplex r01,
EvtComplex r10, EvtComplex r11 )
{
//This routine takes the arguements parent, baryon, and lepton
//number, and a form factor model, and returns a maximum
//probability for this semileptonic form factor model. A
//brute force method is used. The 2D cos theta lepton and
//q2 phase space is probed.
//Start by declaring a particle at rest.
//It only makes sense to have a scalar parent. For now.
//This should be generalized later.
// EvtScalarParticle *scalar_part;
// scalar_part=new EvtScalarParticle;
EvtDiracParticle* dirac_part;
EvtParticle* root_part;
dirac_part = new EvtDiracParticle;
//cludge to avoid generating random numbers!
// scalar_part->noLifeTime();
dirac_part->noLifeTime();
EvtVector4R p_init;
p_init.set( EvtPDL::getMass( parent ), 0.0, 0.0, 0.0 );
// scalar_part->init(parent,p_init);
// root_part=(EvtParticle *)scalar_part;
// root_part->set_type(EvtSpinType::SCALAR);
dirac_part->init( parent, p_init );
root_part = (EvtParticle*)dirac_part;
root_part->setDiagonalSpinDensity();
EvtParticle *daughter, *lep, *trino;
EvtAmp amp;
EvtId listdaug[3];
listdaug[0] = baryon;
listdaug[1] = lepton;
listdaug[2] = nudaug;
amp.init( parent, 3, listdaug );
root_part->makeDaughters( 3, listdaug );
daughter = root_part->getDaug( 0 );
lep = root_part->getDaug( 1 );
trino = root_part->getDaug( 2 );
//cludge to avoid generating random numbers!
daughter->noLifeTime();
lep->noLifeTime();
trino->noLifeTime();
//Initial particle is unpolarized, well it is a scalar so it is
//trivial
EvtSpinDensity rho;
rho.setDiag( root_part->getSpinStates() );
double mass[3];
double m = root_part->mass();
EvtVector4R p4baryon, p4lepton, p4nu, p4w;
double q2max;
double q2, elepton, plepton;
int i, j;
double erho, prho, costl;
double maxfoundprob = 0.0;
double prob = -10.0;
int massiter;
for ( massiter = 0; massiter < 3; massiter++ ) {
mass[0] = EvtPDL::getMass( baryon );
mass[1] = EvtPDL::getMass( lepton );
mass[2] = EvtPDL::getMass( nudaug );
if ( massiter == 1 ) {
mass[0] = EvtPDL::getMinMass( baryon );
}
if ( massiter == 2 ) {
mass[0] = EvtPDL::getMaxMass( baryon );
}
q2max = ( m - mass[0] ) * ( m - mass[0] );
//loop over q2
for ( i = 0; i < 25; i++ ) {
q2 = ( ( i + 0.5 ) * q2max ) / 25.0;
erho = ( m * m + mass[0] * mass[0] - q2 ) / ( 2.0 * m );
prho = sqrt( erho * erho - mass[0] * mass[0] );
p4baryon.set( erho, 0.0, 0.0, -1.0 * prho );
p4w.set( m - erho, 0.0, 0.0, prho );
//This is in the W rest frame
elepton = ( q2 + mass[1] * mass[1] ) / ( 2.0 * sqrt( q2 ) );
plepton = sqrt( elepton * elepton - mass[1] * mass[1] );
double probctl[3];
for ( j = 0; j < 3; j++ ) {
costl = 0.99 * ( j - 1.0 );
//These are in the W rest frame. Need to boost out into
//the B frame.
p4lepton.set( elepton, 0.0, plepton * sqrt( 1.0 - costl * costl ),
plepton * costl );
p4nu.set( plepton, 0.0,
-1.0 * plepton * sqrt( 1.0 - costl * costl ),
-1.0 * plepton * costl );
EvtVector4R boost( ( m - erho ), 0.0, 0.0, 1.0 * prho );
p4lepton = boostTo( p4lepton, boost );
p4nu = boostTo( p4nu, boost );
//Now initialize the daughters...
daughter->init( baryon, p4baryon );
lep->init( lepton, p4lepton );
trino->init( nudaug, p4nu );
CalcAmp( root_part, amp, FormFactors, r00, r01, r10, r11 );
//Now find the probability at this q2 and cos theta lepton point
//and compare to maxfoundprob.
//Do a little magic to get the probability!!
prob = rho.normalizedProb( amp.getSpinDensity() );
probctl[j] = prob;
}
//probclt contains prob at ctl=-1,0,1.
//prob=a+b*ctl+c*ctl^2
double a = probctl[1];
double b = 0.5 * ( probctl[2] - probctl[0] );
double c = 0.5 * ( probctl[2] + probctl[0] ) - probctl[1];
prob = probctl[0];
if ( probctl[1] > prob )
prob = probctl[1];
if ( probctl[2] > prob )
prob = probctl[2];
if ( fabs( c ) > 1e-20 ) {
double ctlx = -0.5 * b / c;
if ( fabs( ctlx ) < 1.0 ) {
double probtmp = a + b * ctlx + c * ctlx * ctlx;
if ( probtmp > prob )
prob = probtmp;
}
}
//EvtGenReport(EVTGEN_DEBUG,"EvtGen") << "prob,probctl:"<<prob<<" "
// << probctl[0]<<" "
// << probctl[1]<<" "
// << probctl[2]<<std::endl;
if ( prob > maxfoundprob ) {
maxfoundprob = prob;
}
}
if ( EvtPDL::getWidth( baryon ) <= 0.0 ) {
//if the particle is narrow dont bother with changing the mass.
massiter = 4;
}
}
root_part->deleteTree();
maxfoundprob *= 1.1;
return maxfoundprob;
}
void EvtSemiLeptonicBaryonAmp::CalcAmp( EvtParticle* parent, EvtAmp& amp,
EvtSemiLeptonicFF* FormFactors,
EvtComplex r00, EvtComplex r01,
EvtComplex r10, EvtComplex r11 )
{
// Leptons
static EvtId EM = EvtPDL::getId( "e-" );
static EvtId MUM = EvtPDL::getId( "mu-" );
static EvtId TAUM = EvtPDL::getId( "tau-" );
// Anti-Leptons
static EvtId EP = EvtPDL::getId( "e+" );
static EvtId MUP = EvtPDL::getId( "mu+" );
static EvtId TAUP = EvtPDL::getId( "tau+" );
// Baryons
static EvtId LAMCP = EvtPDL::getId( "Lambda_c+" );
static EvtId LAMC1P = EvtPDL::getId( "Lambda_c(2593)+" );
static EvtId LAMC2P = EvtPDL::getId( "Lambda_c(2625)+" );
static EvtId LAMB = EvtPDL::getId( "Lambda_b0" );
// Anti-Baryons
static EvtId LAMCM = EvtPDL::getId( "anti-Lambda_c-" );
static EvtId LAMC1M = EvtPDL::getId( "anti-Lambda_c(2593)-" );
static EvtId LAMC2M = EvtPDL::getId( "anti-Lambda_c(2625)-" );
static EvtId LAMBB = EvtPDL::getId( "anti-Lambda_b0" );
// Set the spin density matrix of the parent baryon
EvtSpinDensity rho;
rho.setDim( 2 );
rho.set( 0, 0, r00 );
rho.set( 0, 1, r01 );
rho.set( 1, 0, r10 );
rho.set( 1, 1, r11 );
EvtVector4R vector4P = parent->getP4Lab();
double pmag = vector4P.d3mag();
double cosTheta = vector4P.get( 3 ) / pmag;
double theta = acos( cosTheta );
double phi = atan2( vector4P.get( 2 ), vector4P.get( 1 ) );
parent->setSpinDensityForwardHelicityBasis( rho, phi, theta, 0.0 );
//parent->setSpinDensityForward(rho);
// Set the four momentum of the parent baryon in it's rest frame
EvtVector4R p4b;
p4b.set( parent->mass(), 0.0, 0.0, 0.0 );
// Get the four momentum of the daughter baryon in the parent's rest frame
EvtVector4R p4daught = parent->getDaug( 0 )->getP4();
// Add the lepton and neutrino 4 momenta to find q (q^2)
EvtVector4R q = parent->getDaug( 1 )->getP4() + parent->getDaug( 2 )->getP4();
double q2 = q.mass2();
EvtId l_num = parent->getDaug( 1 )->getId();
EvtId bar_num = parent->getDaug( 0 )->getId();
EvtId par_num = parent->getId();
double baryonmass = parent->getDaug( 0 )->mass();
// Handle spin-1/2 daughter baryon Dirac spinor cases
if ( EvtPDL::getSpinType( parent->getDaug( 0 )->getId() ) ==
EvtSpinType::DIRAC ) {
// Set the form factors
double f1, f2, f3, g1, g2, g3;
FormFactors->getdiracff( par_num, bar_num, q2, baryonmass, &f1, &f2,
&f3, &g1, &g2, &g3 );
const double form_fact[6] = {f1, f2, f3, g1, g2, g3};
EvtVector4C b11, b12, b21, b22, l1, l2;
// Lepton Current
if ( l_num == EM || l_num == MUM || l_num == TAUM ) {
l1 = EvtLeptonVACurrent( parent->getDaug( 1 )->spParent( 0 ),
parent->getDaug( 2 )->spParentNeutrino() );
l2 = EvtLeptonVACurrent( parent->getDaug( 1 )->spParent( 1 ),
parent->getDaug( 2 )->spParentNeutrino() );
} else if ( l_num == EP || l_num == MUP || l_num == TAUP ) {
l1 = EvtLeptonVACurrent( parent->getDaug( 2 )->spParentNeutrino(),
parent->getDaug( 1 )->spParent( 0 ) );
l2 = EvtLeptonVACurrent( parent->getDaug( 2 )->spParentNeutrino(),
parent->getDaug( 1 )->spParent( 1 ) );
} else {
EvtGenReport( EVTGEN_ERROR, "EvtGen" ) << "Wrong lepton number \n";
::abort();
}
// Baryon current
// Flag for particle/anti-particle parent, daughter with same/opp. parity
// pflag = 0 => particle, same parity parent, daughter
// pflag = 1 => particle, opp. parity parent, daughter
// pflag = 2 => anti-particle, same parity parent, daughter
// pflag = 3 => anti-particle, opp. parity parent, daughter
int pflag = 0;
// Handle 1/2+ -> 1/2+ first
if ( ( par_num == LAMB && bar_num == LAMCP ) ||
( par_num == LAMBB && bar_num == LAMCM ) ) {
// Set particle/anti-particle flag
if ( bar_num == LAMCP )
pflag = 0;
else if ( bar_num == LAMCM )
pflag = 2;
b11 = EvtBaryonVACurrent( parent->getDaug( 0 )->spParent( 0 ),
parent->sp( 0 ), p4b, p4daught, form_fact,
pflag );
b21 = EvtBaryonVACurrent( parent->getDaug( 0 )->spParent( 0 ),
parent->sp( 1 ), p4b, p4daught, form_fact,
pflag );
b12 = EvtBaryonVACurrent( parent->getDaug( 0 )->spParent( 1 ),
parent->sp( 0 ), p4b, p4daught, form_fact,
pflag );
b22 = EvtBaryonVACurrent( parent->getDaug( 0 )->spParent( 1 ),
parent->sp( 1 ), p4b, p4daught, form_fact,
pflag );
}
// Handle 1/2+ -> 1/2- second
else if ( ( par_num == LAMB && bar_num == LAMC1P ) ||
( par_num == LAMBB && bar_num == LAMC1M ) ) {
// Set particle/anti-particle flag
if ( bar_num == LAMC1P )
pflag = 1;
else if ( bar_num == LAMC1M )
pflag = 3;
b11 = EvtBaryonVACurrent( ( parent->getDaug( 0 )->spParent( 0 ) ),
( EvtGammaMatrix::g5() * parent->sp( 0 ) ),
p4b, p4daught, form_fact, pflag );
b21 = EvtBaryonVACurrent( ( parent->getDaug( 0 )->spParent( 0 ) ),
( EvtGammaMatrix::g5() * parent->sp( 1 ) ),
p4b, p4daught, form_fact, pflag );
b12 = EvtBaryonVACurrent( ( parent->getDaug( 0 )->spParent( 1 ) ),
( EvtGammaMatrix::g5() * parent->sp( 0 ) ),
p4b, p4daught, form_fact, pflag );
b22 = EvtBaryonVACurrent( ( parent->getDaug( 0 )->spParent( 1 ) ),
( EvtGammaMatrix::g5() * parent->sp( 1 ) ),
p4b, p4daught, form_fact, pflag );
}
else {
EvtGenReport( EVTGEN_ERROR, "EvtGen" )
<< "Dirac semilep. baryon current "
<< "not implemented for this decay sequence." << std::endl;
::abort();
}
amp.vertex( 0, 0, 0, l1 * b11 );
amp.vertex( 0, 0, 1, l2 * b11 );
amp.vertex( 1, 0, 0, l1 * b21 );
amp.vertex( 1, 0, 1, l2 * b21 );
amp.vertex( 0, 1, 0, l1 * b12 );
amp.vertex( 0, 1, 1, l2 * b12 );
amp.vertex( 1, 1, 0, l1 * b22 );
amp.vertex( 1, 1, 1, l2 * b22 );
}
// Need special handling for the spin-3/2 daughter baryon
// Rarita-Schwinger spinor cases
else if ( EvtPDL::getSpinType( parent->getDaug( 0 )->getId() ) ==
EvtSpinType::RARITASCHWINGER ) {
// Set the form factors
double f1, f2, f3, f4, g1, g2, g3, g4;
FormFactors->getraritaff( par_num, bar_num, q2, baryonmass, &f1, &f2,
&f3, &f4, &g1, &g2, &g3, &g4 );
const double form_fact[8] = {f1, f2, f3, f4, g1, g2, g3, g4};
EvtId l_num = parent->getDaug( 1 )->getId();
EvtVector4C b11, b12, b21, b22, b13, b23, b14, b24, l1, l2;
// Lepton Current
if ( l_num == EM || l_num == MUM || l_num == TAUM ) {
// Lepton Current
l1 = EvtLeptonVACurrent( parent->getDaug( 1 )->spParent( 0 ),
parent->getDaug( 2 )->spParentNeutrino() );
l2 = EvtLeptonVACurrent( parent->getDaug( 1 )->spParent( 1 ),
parent->getDaug( 2 )->spParentNeutrino() );
} else if ( l_num == EP || l_num == MUP || l_num == TAUP ) {
l1 = EvtLeptonVACurrent( parent->getDaug( 2 )->spParentNeutrino(),
parent->getDaug( 1 )->spParent( 0 ) );
l2 = EvtLeptonVACurrent( parent->getDaug( 2 )->spParentNeutrino(),
parent->getDaug( 1 )->spParent( 1 ) );
} else {
EvtGenReport( EVTGEN_ERROR, "EvtGen" ) << "Wrong lepton number \n";
}
// Baryon Current
// Declare particle, anti-particle flag, same/opp. parity
// pflag = 0 => particle
// pflag = 1 => anti-particle
int pflag = 0;
// Handle cases of 1/2+ -> 3/2-
if ( par_num == LAMB && bar_num == LAMC2P ) {
// Set flag for particle case
pflag = 0;
} else if ( par_num == LAMBB && bar_num == LAMC2M ) {
// Set flag for anti-particle case
pflag = 1;
} else {
EvtGenReport( EVTGEN_ERROR, "EvtGen" )
<< "Rarita-Schwinger semilep. baryon current "
<< "not implemented for this decay sequence." << std::endl;
::abort();
}
// Baryon current
b11 = EvtBaryonVARaritaCurrent( parent->getDaug( 0 )->spRSParent( 0 ),
parent->sp( 0 ), p4b, p4daught,
form_fact, pflag );
b21 = EvtBaryonVARaritaCurrent( parent->getDaug( 0 )->spRSParent( 0 ),
parent->sp( 1 ), p4b, p4daught,
form_fact, pflag );
b12 = EvtBaryonVARaritaCurrent( parent->getDaug( 0 )->spRSParent( 1 ),
parent->sp( 0 ), p4b, p4daught,
form_fact, pflag );
b22 = EvtBaryonVARaritaCurrent( parent->getDaug( 0 )->spRSParent( 1 ),
parent->sp( 1 ), p4b, p4daught,
form_fact, pflag );
b13 = EvtBaryonVARaritaCurrent( parent->getDaug( 0 )->spRSParent( 2 ),
parent->sp( 0 ), p4b, p4daught,
form_fact, pflag );
b23 = EvtBaryonVARaritaCurrent( parent->getDaug( 0 )->spRSParent( 2 ),
parent->sp( 1 ), p4b, p4daught,
form_fact, pflag );
b14 = EvtBaryonVARaritaCurrent( parent->getDaug( 0 )->spRSParent( 3 ),
parent->sp( 0 ), p4b, p4daught,
form_fact, pflag );
b24 = EvtBaryonVARaritaCurrent( parent->getDaug( 0 )->spRSParent( 3 ),
parent->sp( 1 ), p4b, p4daught,
form_fact, pflag );
amp.vertex( 0, 0, 0, l1 * b11 );
amp.vertex( 0, 0, 1, l2 * b11 );
amp.vertex( 1, 0, 0, l1 * b21 );
amp.vertex( 1, 0, 1, l2 * b21 );
amp.vertex( 0, 1, 0, l1 * b12 );
amp.vertex( 0, 1, 1, l2 * b12 );
amp.vertex( 1, 1, 0, l1 * b22 );
amp.vertex( 1, 1, 1, l2 * b22 );
amp.vertex( 0, 2, 0, l1 * b13 );
amp.vertex( 0, 2, 1, l2 * b13 );
amp.vertex( 1, 2, 0, l1 * b23 );
amp.vertex( 1, 2, 1, l2 * b23 );
amp.vertex( 0, 3, 0, l1 * b14 );
amp.vertex( 0, 3, 1, l2 * b14 );
amp.vertex( 1, 3, 0, l1 * b24 );
amp.vertex( 1, 3, 1, l2 * b24 );
}
}
EvtVector4C EvtSemiLeptonicBaryonAmp::EvtBaryonVACurrent(
const EvtDiracSpinor& Bf, const EvtDiracSpinor& Bi, EvtVector4R parent,
EvtVector4R daught, const double* ff, int pflag )
{
// flag == 0 => particle, same parity
// flag == 1 => particle, opposite parity
// flag == 2 => anti-particle, same parity
// flag == 3 => anti-particle, opposite parity
// particle
EvtComplex cv = EvtComplex( 1.0, 0. );
EvtComplex ca = EvtComplex( 1.0, 0. );
EvtComplex cg0 = EvtComplex( 1.0, 0. );
EvtComplex cg5 = EvtComplex( 1.0, 0. );
// antiparticle- same parity parent & daughter
if ( pflag == 2 ) {
cv = EvtComplex( -1.0, 0. );
ca = EvtComplex( 1.0, 0. );
cg0 = EvtComplex( 1.0, 0.0 );
cg5 = EvtComplex( 0.0, -1.0 );
}
// antiparticle- opposite parity parent & daughter
else if ( pflag == 3 ) {
cv = EvtComplex( 1.0, 0. );
ca = EvtComplex( -1.0, 0. );
cg0 = EvtComplex( 0.0, -1.0 );
cg5 = EvtComplex( 1.0, 0.0 );
}
EvtVector4C t[6];
// Term 1 = \bar{u}(p',s')*(F_1(q^2)*\gamma_{mu})*u(p,s)
t[0] = cv * EvtLeptonVCurrent( Bf, Bi );
// Term 2 = \bar{u}(p',s')*(F_2(q^2)*(p_{mu}/m_{\Lambda_Q}))*u(p,s)
t[1] = cg0 * EvtLeptonSCurrent( Bf, Bi ) * ( parent / parent.mass() );
// Term 3 = \bar{u}(p',s')*(F_3(q^2)*(p'_{mu}/m_{\Lambda_q}))*u(p,s)
t[2] = cg0 * EvtLeptonSCurrent( Bf, Bi ) * ( daught / daught.mass() );
// Term 4 = \bar{u}(p',s')*(G_1(q^2)*\gamma_{mu}*\gamma_5)*u(p,s)
t[3] = ca * EvtLeptonACurrent( Bf, Bi );
// Term 5 = \bar{u}(p',s')*(G_2(q^2)*(p_{mu}/m_{\Lambda_Q})*\gamma_5)*u(p,s)
t[4] = cg5 * EvtLeptonPCurrent( Bf, Bi ) * ( parent / parent.mass() );
// Term 6 = \bar{u}(p',s')*(G_3(q^2)*(p'_{mu}/m_{\Lambda_q})*\gamma_5)*u(p,s)
t[5] = cg5 * EvtLeptonPCurrent( Bf, Bi ) * ( daught / daught.mass() );
// Sum the individual terms
EvtVector4C current = ( ff[0] * t[0] + ff[1] * t[1] + ff[2] * t[2] -
ff[3] * t[3] - ff[4] * t[4] - ff[5] * t[5] );
return current;
}
EvtVector4C EvtSemiLeptonicBaryonAmp::EvtBaryonVARaritaCurrent(
const EvtRaritaSchwinger& Bf, const EvtDiracSpinor& Bi, EvtVector4R parent,
EvtVector4R daught, const double* ff, int pflag )
{
// flag == 0 => particle
// flag == 1 => anti-particle
// particle
EvtComplex cv = EvtComplex( 1.0, 0. );
EvtComplex ca = EvtComplex( 1.0, 0. );
EvtComplex cg0 = EvtComplex( 1.0, 0. );
EvtComplex cg5 = EvtComplex( 1.0, 0. );
// antiparticle
if ( pflag == 1 ) {
cv = EvtComplex( -1.0, 0. );
ca = EvtComplex( 1.0, 0. );
cg0 = EvtComplex( 1.0, 0.0 );
cg5 = EvtComplex( 0.0, -1.0 );
}
EvtVector4C t[8];
EvtTensor4C id;
id.setdiag( 1.0, 1.0, 1.0, 1.0 );
EvtDiracSpinor tmp;
for ( int i = 0; i < 4; i++ ) {
tmp.set_spinor( i, Bf.getVector( i ) * parent );
}
EvtVector4C v1, v2;
for ( int i = 0; i < 4; i++ ) {
v1.set( i, EvtLeptonSCurrent( Bf.getSpinor( i ), Bi ) );
v2.set( i, EvtLeptonPCurrent( Bf.getSpinor( i ), Bi ) );
}
// Term 1 = \bar{u}^{\alpha}(p',s')*(p_{\alpha}/m_{\Lambda_Q})*(F_1(q^2)*\gamma_{mu})*u(p,s)
t[0] = ( cv / parent.mass() ) * EvtLeptonVCurrent( tmp, Bi );
// Term 2
// = \bar{u}^{\alpha}(p',s')*(p_{\alpha}/m_{\Lambda_Q})*(F_2(q^2)*(p_{mu}/m_{\Lambda_Q}))*u(p,s)
t[1] = ( ( cg0 / parent.mass() ) * EvtLeptonSCurrent( tmp, Bi ) ) *
( parent / parent.mass() );
// Term 3
// = \bar{u}^{\alpha}(p',s')*(p_{\alpha}/m_{\Lambda_Q})*(F_3(q^2)*(p'_{mu}/m_{\Lambda_q}))*u(p,s)
t[2] = ( ( cg0 / parent.mass() ) * EvtLeptonSCurrent( tmp, Bi ) ) *
( daught / daught.mass() );
// Term 4 = \bar{u}^{\alpha}(p',s')*(F_4(q^2)*g_{\alpha,\mu})*u(p,s)
t[3] = cg0 * ( id.cont2( v1 ) );
// Term 5
// = \bar{u}^{\alpha}(p',s')*(p_{\alpha}/m_{\Lambda_Q})*(G_1(q^2)*\gamma_{mu}*\gamma_5)*u(p,s)
t[4] = ( ca / parent.mass() ) * EvtLeptonACurrent( tmp, Bi );
// Term 6
// = \bar{u}^{\alpha}(p',s')*(p_{\alpha}/m_{\Lambda_Q})
// *(G_2(q^2)*(p_{mu}/m_{\Lambda_Q})*\gamma_5)*u(p,s)
t[5] = ( ( cg5 / parent.mass() ) * EvtLeptonPCurrent( tmp, Bi ) ) *
( parent / parent.mass() );
// Term 7
// = \bar{u}^{\alpha}(p',s')*(p_{\alpha}/m_{\Lambda_Q})
// *(G_3(q^2)*(p'_{mu}/m_{\Lambda_q})*\gamma_5)*u(p,s)
t[6] = ( ( cg5 / parent.mass() ) * EvtLeptonPCurrent( tmp, Bi ) ) *
( daught / daught.mass() );
// Term 8 = \bar{u}^{\alpha}(p',s')*(G_4(q^2)*g_{\alpha,\mu}*\gamma_5))*u(p,s)
t[7] = cg5 * ( id.cont2( v2 ) );
// Sum the individual terms
EvtVector4C current = ( ff[0] * t[0] + ff[1] * t[1] + ff[2] * t[2] +
ff[3] * t[3] - ff[4] * t[4] - ff[5] * t[5] -
ff[6] * t[6] - ff[7] * t[7] );
return current;
}

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