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SSGNGVertex.cc
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SSGNGVertex.cc
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// -*- C++ -*-
//
// SSGNGVertex.cc is a part of Herwig++ - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2011 The Herwig Collaboration
//
// Herwig++ is licenced under version 2 of the GPL, see COPYING for details.
// Please respect the MCnet academic guidelines, see GUIDELINES for details.
//
//
// This is the implementation of the non-inlined, non-templated member
// functions of the SSGNGVertex class.
//
#include "SSGNGVertex.h"
#include "ThePEG/Utilities/DescribeClass.h"
#include "ThePEG/Interface/Switch.h"
#include "ThePEG/Interface/ClassDocumentation.h"
#include "ThePEG/Persistency/PersistentOStream.h"
#include "ThePEG/Persistency/PersistentIStream.h"
#include "Herwig++/Models/Susy/MixingMatrix.h"
#include "ThePEG/PDT/EnumParticles.h"
#include "Herwig++/Looptools/clooptools.h"
using namespace ThePEG::Helicity;
using namespace Herwig;
namespace {
unsigned int neutralinoIndex(long id) {
if(id> 1000000)
return id<1000025 ? id-1000022 : (id-1000005)/10;
else if(abs(id)<=16)
return (abs(id)-4)/2;
else
return id-13;
}
}
SSGNGVertex::SSGNGVertex() : _includeOnShell(false), _realIntegral(false),
_omitLightQuarkYukawas(false),
_sw(0.), _cw(0.), _idlast(0),
_q2last(ZERO), _couplast(0.),
_leftlast(ZERO), _rightlast(ZERO) {
orderInGem(1);
orderInGs(2);
}
void SSGNGVertex::doinit() {
Looptools::ltini();
tMSSMPtr model = dynamic_ptr_cast<tMSSMPtr>(generator()->standardModel());
if(!model)
throw InitException() << "SSGNGVertex::doinit() - "
<< "The model pointer is null."
<< Exception::abortnow;
_theN = model->neutralinoMix();
if(!_theN )
throw InitException() << "SSGNGVertex::doinit - The neutralino "
<< "mixing matrix pointer is null."
<< Exception::abortnow;
vector<long> ineu(4);
ineu[0] = 1000022; ineu[1] = 1000023;
ineu[2] = 1000025; ineu[3] = 1000035;
if(_theN->size().first==5)
ineu.push_back(1000045);
else if(_theN->size().first==7) {
if(model->majoranaNeutrinos()) {
ineu.push_back(17);
ineu.push_back(18);
ineu.push_back(19);
}
else {
ineu.push_back(12);
ineu.push_back(14);
ineu.push_back(16);
}
}
for(unsigned int i = 0; i < ineu.size(); ++i) {
addToList(1000021, ineu[i], 21);
}
GeneralFFVVertex::doinit();
_sw = sqrt(sin2ThetaW());
_cw = sqrt(1 - _sw*_sw);
_mw = getParticleData(ParticleID::Wplus)->mass();
double tb = model->tanBeta();
_sb = tb/sqrt(1 + sqr(tb));
_cb = sqrt(1 - sqr(_sb));
_stop = model->stopMix();
_sbot = model->sbottomMix();
Looptools::ltexi();
}
void SSGNGVertex::dofinish() {
Looptools::ltexi();
GeneralFFVVertex::dofinish();
}
void SSGNGVertex::doinitrun() {
Looptools::ltini();
GeneralFFVVertex::doinitrun();
}
void SSGNGVertex::persistentOutput(PersistentOStream & os) const {
os << _sw << _cw << _theN << ounit(_mw,GeV) << _sb << _cb
<< _stop << _sbot << _includeOnShell << _omitLightQuarkYukawas
<< _realIntegral;
}
void SSGNGVertex::persistentInput(PersistentIStream & is, int) {
is >> _sw >> _cw >> _theN >> iunit(_mw,GeV) >> _sb >> _cb
>> _stop >> _sbot >> _includeOnShell >> _omitLightQuarkYukawas
>> _realIntegral;
}
// Static variable needed for the type description system in ThePEG.
DescribeClass<SSGNGVertex,GeneralFFVVertex>
describeHerwigSSGNGVertex("Herwig::SSGNGVertex", "HwSusy.so");
void SSGNGVertex::Init() {
static ClassDocumentation<SSGNGVertex> documentation
("The loop-mediated coupling of the gluino to a gluon and a neutralino.");
static Switch<SSGNGVertex,bool> interfaceIncludeOnShellIntermediates
("IncludeOnShellIntermediates",
"Whether or not to include on-shell intermediate states",
&SSGNGVertex::_includeOnShell, false, false, false);
static SwitchOption interfaceIncludeOnShellIntermediatesYes
(interfaceIncludeOnShellIntermediates,
"Yes",
"Include them",
true);
static SwitchOption interfaceIncludeOnShellIntermediatesNo
(interfaceIncludeOnShellIntermediates,
"No",
"Don't incldue them",
false);
static Switch<SSGNGVertex,bool> interfaceOmitLightQuarkYukawas
("OmitLightQuarkYukawas",
"Omit the yukawa type couplings for down, up, strange"
" and charm quarks, mainly for testing vs ISAJET",
&SSGNGVertex::_omitLightQuarkYukawas, false, false, false);
static SwitchOption interfaceOmitLightQuarkYukawasNo
(interfaceOmitLightQuarkYukawas,
"No",
"Include the Yukawas",
false);
static SwitchOption interfaceOmitLightQuarkYukawasYes
(interfaceOmitLightQuarkYukawas,
"Yes",
"Omit Yukawas",
true);
static Switch<SSGNGVertex,bool> interfaceRealIntegral
("RealIntegral",
"Only include the real parts of the integrals",
&SSGNGVertex::_realIntegral, false, false, false);
static SwitchOption interfaceRealIntegralYes
(interfaceRealIntegral,
"Yes",
"Only include the real part",
true);
static SwitchOption interfaceRealIntegralNo
(interfaceRealIntegral,
"No",
"Don't include the real part",
false);
}
void SSGNGVertex::setCoupling(Energy2 q2, tcPDPtr part1,
#ifndef NDEBUG
tcPDPtr part2,tcPDPtr part3) {
#else
tcPDPtr part2,tcPDPtr) {
#endif
int o[2]={1,0};
long in1 = part1->id();
long in2 = part2->id();
Energy Mj = part1->mass();
Energy Mi = part2->mass();
if(in1!=ParticleID::SUSY_g) {
swap(in1,in2);
swap(Mj,Mi);
}
// checks of the particle ids
assert(part3->id()==ParticleID::g);
assert(in1 == ParticleID::SUSY_g);
assert(in2 == ParticleID::SUSY_chi_10 || in2 == ParticleID::SUSY_chi_20 ||
in2 == ParticleID::SUSY_chi_30 || in2 == ParticleID::SUSY_chi_40 ||
in2 == 1000045 || in2==12 || in2==14 || in2==16 || in2==17 || in2==18 || in2==19 );
// normal couplings are zero
setLeft (0.);
setRight(0.);
if(in2 != _idlast || q2 !=_q2last) {
Looptools::clearcache();
_leftlast = ZERO;
_rightlast = ZERO;
_idlast = in2;
unsigned int neu = neutralinoIndex(in2);
Complex n1prime = (*_theN)(neu,0)*_cw + (*_theN)(neu,1)*_sw;
Complex n2prime = (*_theN)(neu,1)*_cw - (*_theN)(neu,0)*_sw;
// squark/quark loops
for(long iferm=1;iferm<7;++iferm) {
tcPDPtr smf = getParticleData(iferm);
Energy mf = smf->mass();
double qf = smf->charge()/eplus;
double y = (!(iferm<=4&&_omitLightQuarkYukawas)) ?
0.5*double(dynamic_ptr_cast<tcHwSMPtr>(generator()->standardModel())->mass(q2,smf)/_mw) : 0.;
Complex bracketl = qf*_sw*( conj(n1prime) - _sw*conj(n2prime)/_cw );
double lambda(0.);
// neutralino mixing element
Complex nlf(0.);
if( iferm % 2 == 0 ) {
y /= _sb;
lambda = -0.5 + qf*sqr(_sw);
nlf = (*_theN)(neu,3);
}
else {
y /= _cb;
lambda = 0.5 + qf*sqr(_sw);
nlf = (*_theN)(neu,2);
}
Complex bracketr = _sw*qf*n1prime - n2prime*lambda/_cw;
for(long iy=0;iy<2;++iy) {
long isf = 1000000*(1+iy)+iferm;
Energy msf = getParticleData(isf)->mass();
if(!_includeOnShell&&(mf+msf<Mj||mf+msf<Mi)) continue;
Complex g[2][2];
Complex ma1(0.), ma2(0.);
// heavy fermions
if( iferm == 5 || iferm == 6 ) {
if( iferm == 5 ) {
ma1 = (*_sbot)(iy,0);
ma2 = (*_sbot)(iy,1);
}
else if( iferm == 6 ) {
ma1 = (*_stop)(iy,0);
ma2 = (*_stop)(iy,1);
}
}
else if(iy==0) {
ma1 = 1.;
}
else {
ma2 = 1.;
}
g[0][0] = y*conj(nlf)*ma1 - ma2*bracketl;
g[0][1] = y*nlf *ma2 + ma1*bracketr;
g[1][0] = - ma2;
g[1][1] = + ma1;
swap(g[0][0],g[0][1]);
complex<InvEnergy2> I,J,K,I2;
loopIntegrals(Mi,Mj,msf,mf,I,J,K,I2);
complex<InvEnergy> coup[2];
for(unsigned int ix=0;ix<2;++ix) {
coup[ix] = Mj*(I2-K)*(g[0][ix]*g[1][o[ix]]-conj(g[0][o[ix]]*g[1][ix]))
+Mi*K*(g[0][o[ix]]*g[1][ix]-conj(g[0][ix]*g[1][o[ix]]))
+mf*I*(g[0][ix]*g[1][ix]-conj(g[0][o[ix]]*g[1][o[ix]]));
}
_leftlast += 2.*coup[0];
_rightlast += 2.*coup[1];
}
}
}
if(q2 != _q2last || _couplast==0.) {
_q2last = q2;
_couplast = weakCoupling(q2)*sqr(strongCoupling(q2))/
32./sqr(Constants::pi);
}
norm(_couplast);
setLeftSigma ( _leftlast);
setRightSigma(_rightlast);
}
void SSGNGVertex::loopIntegrals(Energy Mi, Energy Mj, Energy M, Energy m,
complex<InvEnergy2> & I, complex<InvEnergy2> & J,
complex<InvEnergy2> & K, complex<InvEnergy2> & I2) {
Energy2 m2(sqr(m)),M2(sqr(M)),Mi2(sqr(Mi)),Mj2(sqr(Mj));
double min2 = Mj2*UnitRemoval::InvE2;
double mout2 = Mi2*UnitRemoval::InvE2;
double mf2 = m2 *UnitRemoval::InvE2;
double ms2 = M2 *UnitRemoval::InvE2;
I = Looptools::C0i(Looptools::cc0,min2,mout2,0.,mf2,ms2,mf2)*UnitRemoval::InvE2;
J = Looptools::C0i(Looptools::cc0,min2,mout2,0.,ms2,mf2,ms2)*UnitRemoval::InvE2;
I2 =-Looptools::C0i(Looptools::cc1,min2,mout2,0.,mf2,ms2,mf2)*UnitRemoval::InvE2;
K = (1.+Complex(m2*I+M2*J-Mj2*I2))/(Mi2-Mj2);
if(_realIntegral) {
I = I .real();
J = J .real();
I2 = I2.real();
K = K .real();
}
}

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