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diff --git a/Decay/General/FFSDecayer.cc b/Decay/General/FFSDecayer.cc
--- a/Decay/General/FFSDecayer.cc
+++ b/Decay/General/FFSDecayer.cc
@@ -1,405 +1,411 @@
// -*- C++ -*-
//
// FFSDecayer.cc is a part of Herwig - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2017 The Herwig Collaboration
//
// Herwig is licenced under version 3 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 FFSDecayer class.
//
#include "FFSDecayer.h"
#include "ThePEG/Utilities/DescribeClass.h"
#include "ThePEG/Interface/ClassDocumentation.h"
#include "ThePEG/Persistency/PersistentOStream.h"
#include "ThePEG/Persistency/PersistentIStream.h"
#include "ThePEG/PDT/DecayMode.h"
#include "ThePEG/Helicity/WaveFunction/ScalarWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/SpinorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/SpinorBarWaveFunction.h"
#include "Herwig/Utilities/Kinematics.h"
#include "Herwig/Decay/GeneralDecayMatrixElement.h"
using namespace Herwig;
using namespace ThePEG::Helicity;
IBPtr FFSDecayer::clone() const {
return new_ptr(*this);
}
IBPtr FFSDecayer::fullclone() const {
return new_ptr(*this);
}
void FFSDecayer::setDecayInfo(PDPtr incoming, PDPair outgoing,
VertexBasePtr vertex,
map<ShowerInteraction,VertexBasePtr> & inV,
const vector<map<ShowerInteraction,VertexBasePtr> > & outV,
map<ShowerInteraction,VertexBasePtr> ) {
decayInfo(incoming,outgoing);
vertex_ = dynamic_ptr_cast<AbstractFFSVertexPtr>(vertex);
perturbativeVertex_ = dynamic_ptr_cast<FFSVertexPtr> (vertex);
vector<ShowerInteraction> itemp={ShowerInteraction::QCD,ShowerInteraction::QED};
for(auto & inter : itemp) {
incomingVertex_[inter] = dynamic_ptr_cast<AbstractFFVVertexPtr>(inV.at(inter));
- if (outV[0].at(inter)->getName()==VertexType::FFV){
- outgoingVertexF_[inter] = dynamic_ptr_cast<AbstractFFVVertexPtr>(outV[0].at(inter));
- outgoingVertexS_[inter] = dynamic_ptr_cast<AbstractVSSVertexPtr>(outV[1].at(inter));
+ outgoingVertexF_[inter] = AbstractFFVVertexPtr();
+ outgoingVertexS_[inter] = AbstractVSSVertexPtr();
+ if(outV[0].at(inter)) {
+ if (outV[0].at(inter)->getName()==VertexType::FFV)
+ outgoingVertexF_[inter] = dynamic_ptr_cast<AbstractFFVVertexPtr>(outV[0].at(inter));
+ else
+ outgoingVertexS_[inter] = dynamic_ptr_cast<AbstractVSSVertexPtr>(outV[0].at(inter));
}
- else {
- outgoingVertexF_[inter] = dynamic_ptr_cast<AbstractFFVVertexPtr>(outV[1].at(inter));
- outgoingVertexS_[inter] = dynamic_ptr_cast<AbstractVSSVertexPtr>(outV[0].at(inter));
+ if(outV[1].at(inter)) {
+ if (outV[1].at(inter)->getName()==VertexType::FFV)
+ outgoingVertexF_[inter] = dynamic_ptr_cast<AbstractFFVVertexPtr>(outV[1].at(inter));
+ else
+ outgoingVertexS_[inter] = dynamic_ptr_cast<AbstractVSSVertexPtr>(outV[1].at(inter));
}
}
}
void FFSDecayer::persistentOutput(PersistentOStream & os) const {
os << perturbativeVertex_ << vertex_
<< incomingVertex_ << outgoingVertexF_
<< outgoingVertexS_;
}
void FFSDecayer::persistentInput(PersistentIStream & is, int) {
is >> perturbativeVertex_ >> vertex_
>> incomingVertex_ >> outgoingVertexF_
>> outgoingVertexS_;
}
// The following static variable is needed for the type
// description system in ThePEG.
DescribeClass<FFSDecayer,GeneralTwoBodyDecayer>
describeHerwigFFSDecayer("Herwig::FFSDecayer", "Herwig.so");
void FFSDecayer::Init() {
static ClassDocumentation<FFSDecayer> documentation
("The FFSDecayer class implements the decay of a fermion to "
"a fermion and a scalar.");
}
double FFSDecayer::me2(const int , const Particle & inpart,
const ParticleVector & decay,
MEOption meopt) const {
if(!ME())
ME(new_ptr(GeneralDecayMatrixElement(PDT::Spin1Half,PDT::Spin1Half,PDT::Spin0)));
//Need to use different barred or unbarred spinors depending on
//whether particle is cc or not.
int itype[2];
if(inpart.dataPtr()->CC()) itype[0] = inpart.id() > 0? 0:1;
else itype[0] = 2;
if(decay[0]->dataPtr()->CC()) itype[1] = decay[0]->id() > 0? 0:1;
else itype[1] = 2;
bool ferm(itype[0] == 0 || itype[1] == 0 || (itype[0] == 2 && itype[1] == 2));
if(meopt==Initialize) {
// spinors and rho
if(ferm) {
SpinorWaveFunction ::calculateWaveFunctions(wave_,rho_,
const_ptr_cast<tPPtr>(&inpart),
incoming);
if(wave_[0].wave().Type() != SpinorType::u)
for(unsigned int ix = 0; ix < 2; ++ix) wave_ [ix].conjugate();
}
else {
SpinorBarWaveFunction::calculateWaveFunctions(wavebar_,rho_,
const_ptr_cast<tPPtr>(&inpart),
incoming);
if(wavebar_[0].wave().Type() != SpinorType::v)
for(unsigned int ix = 0; ix < 2; ++ix) wavebar_[ix].conjugate();
}
}
// setup spin info when needed
if(meopt==Terminate) {
// for the decaying particle
if(ferm) {
SpinorWaveFunction::
constructSpinInfo(wave_,const_ptr_cast<tPPtr>(&inpart),incoming,true);
SpinorBarWaveFunction::constructSpinInfo(wavebar_,decay[0],outgoing,true);
}
else {
SpinorBarWaveFunction::
constructSpinInfo(wavebar_,const_ptr_cast<tPPtr>(&inpart),incoming,true);
SpinorWaveFunction::constructSpinInfo(wave_,decay[0],outgoing,true);
}
ScalarWaveFunction::constructSpinInfo(decay[1],outgoing,true);
}
if(ferm)
SpinorBarWaveFunction::
calculateWaveFunctions(wavebar_,decay[0],outgoing);
else
SpinorWaveFunction::
calculateWaveFunctions(wave_ ,decay[0],outgoing);
ScalarWaveFunction scal(decay[1]->momentum(),decay[1]->dataPtr(),outgoing);
Energy2 scale(sqr(inpart.mass()));
for(unsigned int if1 = 0; if1 < 2; ++if1) {
for(unsigned int if2 = 0; if2 < 2; ++if2) {
if(ferm) (*ME())(if1, if2, 0) =
vertex_->evaluate(scale,wave_[if1],wavebar_[if2],scal);
else (*ME())(if2, if1, 0) =
vertex_->evaluate(scale,wave_[if1],wavebar_[if2],scal);
}
}
double output = (ME()->contract(rho_)).real()/scale*UnitRemoval::E2;
// colour and identical particle factors
output *= colourFactor(inpart.dataPtr(),decay[0]->dataPtr(),
decay[1]->dataPtr());
// return the answer
return output;
}
Energy FFSDecayer::partialWidth(PMPair inpart, PMPair outa,
PMPair outb) const {
if( inpart.second < outa.second + outb.second ) return ZERO;
if(perturbativeVertex_) {
double mu1(0.),mu2(0.);
tcPDPtr in = inpart.first->CC() ? tcPDPtr(inpart.first->CC()) : inpart.first;
if(outa.first->iSpin() == PDT::Spin1Half) {
mu1 = outa.second/inpart.second;
mu2 = outb.second/inpart.second;
perturbativeVertex_->setCoupling(sqr(inpart.second), in, outa.first, outb.first);
}
else {
mu1 = outb.second/inpart.second;
mu2 = outa.second/inpart.second;
perturbativeVertex_->setCoupling(sqr(inpart.second), in, outb.first, outa.first);
}
double c2 = norm(perturbativeVertex_->norm());
Complex cl = perturbativeVertex_->left();
Complex cr = perturbativeVertex_->right();
double me2 = c2*( (norm(cl) + norm(cr))*(1. + sqr(mu1) - sqr(mu2))
+ 2.*mu1*(conj(cl)*cr + conj(cr)*cl).real() );
Energy pcm = Kinematics::pstarTwoBodyDecay(inpart.second, outa.second,
outb.second);
Energy output = me2*pcm/16./Constants::pi;
// colour factor
output *= colourFactor(inpart.first,outa.first,outb.first);
// return the answer
return output;
}
else {
return GeneralTwoBodyDecayer::partialWidth(inpart,outa,outb);
}
}
double FFSDecayer::threeBodyME(const int , const Particle & inpart,
const ParticleVector & decay,
ShowerInteraction inter, MEOption meopt) {
int iscal (0), iferm (1), iglu (2);
// get location of outgoing fermion/scalar
if(decay[1]->dataPtr()->iSpin()==PDT::Spin0) swap(iscal,iferm);
// work out whether inpart is a fermion or antifermion
int itype[2];
if(inpart.dataPtr()->CC()) itype[0] = inpart.id() > 0 ? 0 : 1;
else itype[0] = 2;
if(decay[iferm]->dataPtr()->CC()) itype[1] = decay[iferm]->id() > 0 ? 0 : 1;
else itype[1] = 2;
bool ferm(itype[0] == 0 || itype[1] == 0 ||
(itype[0] == 2 && itype[1] == 2 && decay[iscal]->id() < 0));
if(meopt==Initialize) {
// create spinor (bar) for decaying particle
if(ferm) {
SpinorWaveFunction::calculateWaveFunctions(wave3_, rho3_, const_ptr_cast<tPPtr>(&inpart),
incoming);
if(wave3_[0].wave().Type() != SpinorType::u)
for(unsigned int ix = 0; ix < 2; ++ix) wave3_[ix].conjugate();
}
else {
SpinorBarWaveFunction::calculateWaveFunctions(wavebar3_,rho3_, const_ptr_cast<tPPtr>(&inpart),
incoming);
if(wavebar3_[0].wave().Type() != SpinorType::v)
for(unsigned int ix = 0; ix < 2; ++ix) wavebar3_[ix].conjugate();
}
}
// setup spin information when needed
if(meopt==Terminate) {
if(ferm) {
SpinorWaveFunction::
constructSpinInfo(wave3_,const_ptr_cast<tPPtr>(&inpart),incoming,true);
SpinorBarWaveFunction::constructSpinInfo(wavebar3_,decay[iferm],outgoing,true);
}
else {
SpinorBarWaveFunction::
constructSpinInfo(wavebar3_,const_ptr_cast<tPPtr>(&inpart),incoming,true);
SpinorWaveFunction::constructSpinInfo(wave3_,decay[iferm],outgoing,true);
}
ScalarWaveFunction::constructSpinInfo( decay[iscal],outgoing,true);
VectorWaveFunction::constructSpinInfo(gluon_, decay[iglu ],outgoing,true,false);
return 0.;
}
// calulate colour factors and number of colour flows
unsigned int nflow;
vector<DVector> cfactors = getColourFactors(inpart, decay, nflow);
if(nflow==2) cfactors[0][1] = cfactors[1][0];
vector<GeneralDecayMEPtr> ME(nflow,new_ptr(GeneralDecayMatrixElement(PDT::Spin1Half, PDT::Spin0,
PDT::Spin1Half, PDT::Spin1)));
// create wavefunctions
if (ferm) SpinorBarWaveFunction::calculateWaveFunctions(wavebar3_, decay[iferm],outgoing);
else SpinorWaveFunction:: calculateWaveFunctions(wave3_ , decay[iferm],outgoing);
ScalarWaveFunction swave3_(decay[iscal]->momentum(), decay[iscal]->dataPtr(),outgoing);
VectorWaveFunction::calculateWaveFunctions(gluon_, decay[iglu ],outgoing,true);
// // gauge invariance test
// gluon_.clear();
// for(unsigned int ix=0;ix<3;++ix) {
// if(ix==1) gluon_.push_back(VectorWaveFunction());
// else {
// gluon_.push_back(VectorWaveFunction(decay[iglu ]->momentum(),
// decay[iglu ]->dataPtr(),10,
// outgoing));
// }
// }
if (! ((incomingVertex_[inter] && (outgoingVertexF_[inter] || outgoingVertexS_[inter])) ||
(outgoingVertexF_[inter] && outgoingVertexS_[inter])))
throw Exception()
<< "Invalid vertices for radiation in FFS decay in FFSDecayer::threeBodyME"
<< Exception::runerror;
// sort out colour flows
int F(1), S(2);
if (decay[iscal]->dataPtr()->iColour()==PDT::Colour3 &&
decay[iferm]->dataPtr()->iColour()==PDT::Colour8)
swap(F,S);
else if (decay[iferm]->dataPtr()->iColour()==PDT::Colour3bar &&
decay[iscal]->dataPtr()->iColour()==PDT::Colour8)
swap(F,S);
Complex diag;
Energy2 scale(sqr(inpart.mass()));
const GeneralTwoBodyDecayer::CFlow & colourFlow
= colourFlows(inpart, decay);
for(unsigned int ifi = 0; ifi < 2; ++ifi) {
for(unsigned int ifo = 0; ifo < 2; ++ifo) {
for(unsigned int ig = 0; ig < 2; ++ig) {
// radiation from the incoming fermion
if(inpart.dataPtr()->coloured()) {
assert(incomingVertex_[inter]);
double gs = incomingVertex_[inter]->strongCoupling(scale);
if (ferm){
SpinorWaveFunction spinorInter =
incomingVertex_[inter]->evaluate(scale,3,inpart.dataPtr(),wave3_[ifi],
gluon_[2*ig],inpart.mass());
if (wave3_[ifi].particle()->PDGName()!=spinorInter.particle()->PDGName())
throw Exception()
<< wave3_[ifi].particle()->PDGName() << " was changed to "
<< spinorInter.particle()->PDGName() << " in FFSDecayer::threeBodyME"
<< Exception::runerror;
diag = vertex_->evaluate(scale,spinorInter,wavebar3_[ifo],swave3_)/gs;
}
else {
SpinorBarWaveFunction spinorBarInter =
incomingVertex_[inter]->evaluate(scale,3,inpart.dataPtr(),wavebar3_[ifi],
gluon_[2*ig],inpart.mass());
if (wavebar3_[ifi].particle()->PDGName()!=spinorBarInter.particle()->PDGName())
throw Exception()
<< wavebar3_[ifi].particle()->PDGName() << " was changed to "
<< spinorBarInter.particle()->PDGName() << " in FFSDecayer::threeBodyME"
<< Exception::runerror;
diag = vertex_->evaluate(scale,wave3_[ifo], spinorBarInter,swave3_)/gs;
}
for(unsigned int ix=0;ix<colourFlow[0].size();++ix) {
(*ME[colourFlow[0][ix].first])(ifi, 0, ifo, ig) +=
colourFlow[0][ix].second*diag;
}
}
// radiation from outgoing fermion
if(decay[iferm]->dataPtr()->coloured()) {
assert(outgoingVertexF_[inter]);
// ensure you get correct outgoing particle from first vertex
tcPDPtr off = decay[iferm]->dataPtr();
if(off->CC()) off = off->CC();
double gs = outgoingVertexF_[inter]->strongCoupling(scale);
if (ferm) {
SpinorBarWaveFunction spinorBarInter =
outgoingVertexF_[inter]->evaluate(scale,3,off,wavebar3_[ifo],
gluon_[2*ig],decay[iferm]->mass());
if(wavebar3_[ifo].particle()->PDGName()!=spinorBarInter.particle()->PDGName())
throw Exception()
<< wavebar3_[ifo].particle()->PDGName() << " was changed to "
<< spinorBarInter.particle()->PDGName() << " in FFSDecayer::threeBodyME"
<< Exception::runerror;
diag = vertex_->evaluate(scale,wave3_[ifi],spinorBarInter,swave3_)/gs;
}
else {
SpinorWaveFunction spinorInter =
outgoingVertexF_[inter]->evaluate(scale,3,off,wave3_[ifo],
gluon_[2*ig],decay[iferm]->mass());
if(wave3_[ifo].particle()->PDGName()!=spinorInter.particle()->PDGName())
throw Exception()
<< wave3_[ifo].particle()->PDGName() << " was changed to "
<< spinorInter.particle()->PDGName() << " in FFSDecayer::threeBodyME"
<< Exception::runerror;
diag = vertex_->evaluate(scale,spinorInter,wavebar3_[ifi],swave3_)/gs;
}
for(unsigned int ix=0;ix<colourFlow[F].size();++ix) {
(*ME[colourFlow[F][ix].first])(ifi, 0, ifo, ig) +=
colourFlow[F][ix].second*diag;
}
}
// radiation from outgoing scalar
if(decay[iscal]->dataPtr()->coloured()) {
assert(outgoingVertexS_[inter]);
// ensure you get correct ougoing particle from first vertex
tcPDPtr off = decay[iscal]->dataPtr();
if(off->CC()) off = off->CC();
double gs = outgoingVertexS_[inter]->strongCoupling(scale);
ScalarWaveFunction scalarInter =
outgoingVertexS_[inter]->evaluate(scale,3,off,gluon_[2*ig],
swave3_,decay[iscal]->mass());
if(swave3_.particle()->PDGName()!=scalarInter.particle()->PDGName())
throw Exception()
<< swave3_ .particle()->PDGName() << " was changed to "
<< scalarInter.particle()->PDGName() << " in FFSDecayer::threeBodyME"
<< Exception::runerror;
if (ferm){
diag = vertex_->evaluate(scale,wave3_[ifi],wavebar3_[ifo],scalarInter)/gs;
}
else {
diag = vertex_->evaluate(scale,wave3_[ifo],wavebar3_[ifi],scalarInter)/gs;
}
for(unsigned int ix=0;ix<colourFlow[S].size();++ix) {
(*ME[colourFlow[S][ix].first])(ifi, 0, ifo, ig) +=
colourFlow[S][ix].second*diag;
}
}
}
}
}
// contract matrices
double output=0.;
for(unsigned int ix=0; ix<nflow; ++ix){
for(unsigned int iy=0; iy<nflow; ++iy){
output+=cfactors[ix][iy]*(ME[ix]->contract(*ME[iy],rho3_)).real();
}
}
output*=(4.*Constants::pi);
// return the answer
return output;
}
diff --git a/Decay/General/FFVDecayer.cc b/Decay/General/FFVDecayer.cc
--- a/Decay/General/FFVDecayer.cc
+++ b/Decay/General/FFVDecayer.cc
@@ -1,425 +1,429 @@
// -*- C++ -*-
//
// FFVDecayer.cc is a part of Herwig - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2017 The Herwig Collaboration
//
// Herwig is licenced under version 3 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 FFVDecayer class.
//
#include "FFVDecayer.h"
#include "ThePEG/Utilities/DescribeClass.h"
#include "ThePEG/Interface/ClassDocumentation.h"
#include "ThePEG/Persistency/PersistentOStream.h"
#include "ThePEG/Persistency/PersistentIStream.h"
#include "ThePEG/PDT/DecayMode.h"
#include "ThePEG/Helicity/WaveFunction/VectorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/SpinorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/SpinorBarWaveFunction.h"
#include "Herwig/Utilities/Kinematics.h"
#include "Herwig/Decay/GeneralDecayMatrixElement.h"
using namespace Herwig;
using namespace ThePEG::Helicity;
IBPtr FFVDecayer::clone() const {
return new_ptr(*this);
}
IBPtr FFVDecayer::fullclone() const {
return new_ptr(*this);
}
void FFVDecayer::setDecayInfo(PDPtr incoming, PDPair outgoing,
VertexBasePtr vertex,
map<ShowerInteraction,VertexBasePtr> & inV,
const vector<map<ShowerInteraction,VertexBasePtr> > & outV,
map<ShowerInteraction,VertexBasePtr> ) {
decayInfo(incoming,outgoing);
vertex_ = dynamic_ptr_cast<AbstractFFVVertexPtr>(vertex);
perturbativeVertex_ = dynamic_ptr_cast<FFVVertexPtr> (vertex);
vector<ShowerInteraction> itemp={ShowerInteraction::QCD,ShowerInteraction::QED};
for(auto & inter : itemp) {
incomingVertex_[inter] = dynamic_ptr_cast<AbstractFFVVertexPtr>(inV.at(inter));
- if (outV[0].at(inter)->getName()==VertexType::FFV){
- outgoingVertexF_[inter] = dynamic_ptr_cast<AbstractFFVVertexPtr>(outV[0].at(inter));
- outgoingVertexV_[inter] = dynamic_ptr_cast<AbstractVVVVertexPtr>(outV[1].at(inter));
+ if(outV[0].at(inter)) {
+ if (outV[0].at(inter)->getName()==VertexType::FFV)
+ outgoingVertexF_[inter] = dynamic_ptr_cast<AbstractFFVVertexPtr>(outV[0].at(inter));
+ else
+ outgoingVertexV_[inter] = dynamic_ptr_cast<AbstractVVVVertexPtr>(outV[0].at(inter));
}
- else {
- outgoingVertexF_[inter] = dynamic_ptr_cast<AbstractFFVVertexPtr>(outV[1].at(inter));
- outgoingVertexV_[inter] = dynamic_ptr_cast<AbstractVVVVertexPtr>(outV[0].at(inter));
+ if(outV[1].at(inter)) {
+ if (outV[1].at(inter)->getName()==VertexType::FFV)
+ outgoingVertexF_[inter] = dynamic_ptr_cast<AbstractFFVVertexPtr>(outV[1].at(inter));
+ else
+ outgoingVertexV_[inter] = dynamic_ptr_cast<AbstractVVVVertexPtr>(outV[1].at(inter));
}
}
}
void FFVDecayer::persistentOutput(PersistentOStream & os) const {
os << vertex_ << perturbativeVertex_
<< incomingVertex_ << outgoingVertexF_
<< outgoingVertexV_;
}
void FFVDecayer::persistentInput(PersistentIStream & is, int) {
is >> vertex_ >> perturbativeVertex_
>> incomingVertex_ >> outgoingVertexF_
>> outgoingVertexV_;
}
double FFVDecayer::me2(const int , const Particle & inpart,
const ParticleVector & decay,
MEOption meopt) const {
if(!ME())
ME(new_ptr(GeneralDecayMatrixElement(PDT::Spin1Half,PDT::Spin1Half,PDT::Spin1)));
// type of process
int itype[2];
- if(inpart.dataPtr()->CC()) itype[0] = inpart.id() > 0 ? 0 : 1;
- else itype[0] = 2;
+ if(inpart.dataPtr()->CC()) itype[0] = inpart.id() > 0 ? 0 : 1;
+ else itype[0] = 2;
if(decay[0]->dataPtr()->CC()) itype[1] = decay[0]->id() > 0 ? 0 : 1;
- else itype[1] = 2;
+ else itype[1] = 2;
//Need to use different barred or unbarred spinors depending on
//whether particle is cc or not.
bool ferm(itype[0] == 0 || itype[1] == 0 || (itype[0] == 2 && itype[1] == 2));
if(meopt==Initialize) {
// spinors and rho
if(ferm) {
SpinorWaveFunction ::calculateWaveFunctions(wave_,rho_,
const_ptr_cast<tPPtr>(&inpart),
incoming);
if(wave_[0].wave().Type() != SpinorType::u)
for(unsigned int ix = 0; ix < 2; ++ix) wave_ [ix].conjugate();
}
else {
SpinorBarWaveFunction::calculateWaveFunctions(wavebar_,rho_,
const_ptr_cast<tPPtr>(&inpart),
incoming);
if(wavebar_[0].wave().Type() != SpinorType::v)
for(unsigned int ix = 0; ix < 2; ++ix) wavebar_[ix].conjugate();
}
}
// setup spin info when needed
if(meopt==Terminate) {
// for the decaying particle
if(ferm) {
SpinorWaveFunction::
constructSpinInfo(wave_,const_ptr_cast<tPPtr>(&inpart),incoming,true);
SpinorBarWaveFunction::constructSpinInfo(wavebar_,decay[0],outgoing,true);
}
else {
SpinorBarWaveFunction::
constructSpinInfo(wavebar_,const_ptr_cast<tPPtr>(&inpart),incoming,true);
SpinorWaveFunction::constructSpinInfo(wave_,decay[0],outgoing,true);
}
VectorWaveFunction::
constructSpinInfo(vector_,decay[1],outgoing,true,false);
}
Energy2 scale(sqr(inpart.mass()));
if(ferm)
SpinorBarWaveFunction::
calculateWaveFunctions(wavebar_,decay[0],outgoing);
else
SpinorWaveFunction::
calculateWaveFunctions(wave_ ,decay[0],outgoing);
bool massless = decay[1]->dataPtr()->mass()==ZERO;
VectorWaveFunction::
calculateWaveFunctions(vector_,decay[1],outgoing,massless);
for(unsigned int if1 = 0; if1 < 2; ++if1) {
for(unsigned int if2 = 0; if2 < 2; ++if2) {
for(unsigned int vhel = 0; vhel < 3; ++vhel) {
if(massless && vhel == 1) ++vhel;
if(ferm)
(*ME())(if1, if2,vhel) =
vertex_->evaluate(scale,wave_[if1],wavebar_[if2],vector_[vhel]);
else
(*ME())(if2, if1, vhel) =
vertex_->evaluate(scale,wave_[if1],wavebar_[if2],vector_[vhel]);
}
}
}
double output=(ME()->contract(rho_)).real()/scale*UnitRemoval::E2;
// colour and identical particle factors
output *= colourFactor(inpart.dataPtr(),decay[0]->dataPtr(),decay[1]->dataPtr());
// return the answer
return output;
}
Energy FFVDecayer::partialWidth(PMPair inpart, PMPair outa,
PMPair outb) const {
if( inpart.second < outa.second + outb.second ) return ZERO;
if(perturbativeVertex_) {
double mu1(outa.second/inpart.second),mu2(outb.second/inpart.second);
tcPDPtr in = inpart.first->CC() ? tcPDPtr(inpart.first->CC()) : inpart.first;
if( outa.first->iSpin() == PDT::Spin1Half)
perturbativeVertex_->setCoupling(sqr(inpart.second), in,
outa.first, outb.first);
else {
swap(mu1,mu2);
perturbativeVertex_->setCoupling(sqr(inpart.second),in,
outb.first,outa.first);
}
Complex cl(perturbativeVertex_->left()),cr(perturbativeVertex_->right());
double me2(0.);
if( mu2 > 0. ) {
me2 = (norm(cl) + norm(cr))*(1. + sqr(mu1*mu2) + sqr(mu2)
- 2.*sqr(mu1) - 2.*sqr(mu2*mu2)
+ sqr(mu1*mu1))
- 6.*mu1*sqr(mu2)*(conj(cl)*cr + conj(cr)*cl).real();
me2 /= sqr(mu2);
}
else
me2 = 2.*( (norm(cl) + norm(cr))*(sqr(mu1) + 1.)
- 4.*mu1*(conj(cl)*cr + conj(cr)*cl).real() );
Energy pcm = Kinematics::pstarTwoBodyDecay(inpart.second, outa.second,
outb.second);
Energy output = norm(perturbativeVertex_->norm())*me2*pcm/16./Constants::pi;
// colour factor
output *= colourFactor(inpart.first,outa.first,outb.first);
// return the answer
return output;
}
else {
return GeneralTwoBodyDecayer::partialWidth(inpart,outa,outb);
}
}
// The following static variable is needed for the type
// description system in ThePEG.
DescribeClass<FFVDecayer,GeneralTwoBodyDecayer>
describeHerwigFFVDecayer("Herwig::FFVDecayer", "Herwig.so");
void FFVDecayer::Init() {
static ClassDocumentation<FFVDecayer> documentation
("There is no documentation for the FFVDecayer class");
}
double FFVDecayer::threeBodyME(const int , const Particle & inpart,
const ParticleVector & decay,
ShowerInteraction inter, MEOption meopt) {
int iferm (0), ivect (1), iglu (2);
// get location of outgoing lepton/vector
if(decay[1]->dataPtr()->iSpin()==PDT::Spin1Half) swap(iferm,ivect);
// work out whether inpart is a fermion or antifermion
int itype[2];
if(inpart.dataPtr()->CC()) itype[0] = inpart.id() > 0 ? 0 : 1;
else itype[0] = 2;
if(decay[iferm]->dataPtr()->CC()) itype[1] = decay[iferm]->id() > 0 ? 0 : 1;
else itype[1] = 2;
bool ferm(itype[0] == 0 || itype[1] == 0 ||
(itype[0] == 2 && itype[1] == 2 && decay[ivect]->id() < 0));
// no emissions from massive vectors
bool massless = decay[ivect]->dataPtr()->mass()==ZERO;
if (outgoingVertexV_[inter] && (! massless))
throw Exception()
<< "No dipoles available for massive vectors in FFVDecayer::threeBodyME"
<< Exception::runerror;
if(meopt==Initialize) {
// create spinor (bar) for decaying particle
if(ferm) {
SpinorWaveFunction::calculateWaveFunctions(wave3_, rho3_, const_ptr_cast<tPPtr>(&inpart),
incoming);
if(wave3_[0].wave().Type() != SpinorType::u)
for(unsigned int ix = 0; ix < 2; ++ix) wave3_[ix].conjugate();
}
else {
SpinorBarWaveFunction::calculateWaveFunctions(wavebar3_,rho3_, const_ptr_cast<tPPtr>(&inpart),
incoming);
if(wavebar3_[0].wave().Type() != SpinorType::v)
for(unsigned int ix = 0; ix < 2; ++ix) wavebar3_[ix].conjugate();
}
}
// setup spin information when needed
if(meopt==Terminate) {
if(ferm) {
SpinorWaveFunction::
constructSpinInfo(wave3_,const_ptr_cast<tPPtr>(&inpart),incoming,true);
SpinorBarWaveFunction::constructSpinInfo(wavebar3_,decay[iferm],outgoing,true);
}
else {
SpinorBarWaveFunction::
constructSpinInfo(wavebar3_,const_ptr_cast<tPPtr>(&inpart),incoming,true);
SpinorWaveFunction::constructSpinInfo(wave3_,decay[iferm],outgoing,true);
}
VectorWaveFunction::constructSpinInfo(vector3_, decay[ivect],outgoing,true,massless);
VectorWaveFunction::constructSpinInfo(gluon_, decay[iglu ],outgoing,true,false);
return 0.;
}
// calulate colour factors and number of colour flows
unsigned int nflow;
vector<DVector> cfactors = getColourFactors(inpart, decay, nflow);
if(nflow==2) cfactors[0][1] = cfactors[1][0];
vector<GeneralDecayMEPtr> ME(nflow,new_ptr(GeneralDecayMatrixElement(PDT::Spin1Half, PDT::Spin1Half,
PDT::Spin1, PDT::Spin1)));
// create wavefunctions
if (ferm) SpinorBarWaveFunction::calculateWaveFunctions(wavebar3_, decay[iferm],outgoing);
else SpinorWaveFunction:: calculateWaveFunctions(wave3_ , decay[iferm],outgoing);
VectorWaveFunction::calculateWaveFunctions(vector3_, decay[ivect],outgoing,massless);
VectorWaveFunction::calculateWaveFunctions(gluon_, decay[iglu ],outgoing,true );
// // gauge invariance test
// gluon_.clear();
// for(unsigned int ix=0;ix<3;++ix) {
// if(ix==1) gluon_.push_back(VectorWaveFunction());
// else {
// gluon_.push_back(VectorWaveFunction(decay[iglu ]->momentum(),
// decay[iglu ]->dataPtr(),10,
// outgoing));
// }
// }
if (! ((incomingVertex_[inter] && (outgoingVertexF_[inter] || outgoingVertexV_[inter])) ||
(outgoingVertexF_[inter] && outgoingVertexV_[inter])))
throw Exception()
<< "Invalid vertices for QCD radiation in FFV decay in FFVDecayer::threeBodyME"
<< Exception::runerror;
// sort out colour flows
int F(1), V(2);
if (decay[iferm]->dataPtr()->iColour()==PDT::Colour3bar &&
decay[ivect]->dataPtr()->iColour()==PDT::Colour8)
swap(F,V);
else if (decay[ivect]->dataPtr()->iColour()==PDT::Colour3 &&
decay[iferm]->dataPtr()->iColour()==PDT::Colour8)
swap(F,V);
Complex diag;
Energy2 scale(sqr(inpart.mass()));
const GeneralTwoBodyDecayer::CFlow & colourFlow
= colourFlows(inpart, decay);
for(unsigned int ifi = 0; ifi < 2; ++ifi) {
for(unsigned int ifo = 0; ifo < 2; ++ifo) {
for(unsigned int iv = 0; iv < 3; ++iv) {
for(unsigned int ig = 0; ig < 2; ++ig) {
// radiation from the incoming fermion
if(inpart.dataPtr()->coloured()) {
assert(incomingVertex_[inter]);
double gs = incomingVertex_[inter]->strongCoupling(scale);
if (ferm){
SpinorWaveFunction spinorInter =
incomingVertex_[inter]->evaluate(scale,3,inpart.dataPtr(),wave3_[ifi],
gluon_[2*ig],inpart.mass());
if (wave3_[ifi].particle()->PDGName()!=spinorInter.particle()->PDGName())
throw Exception()
<< wave3_[ifi].particle()->PDGName() << " was changed to "
<< spinorInter.particle()->PDGName() << " in FFVDecayer::threeBodyME"
<< Exception::runerror;
diag = vertex_->evaluate(scale,spinorInter,wavebar3_[ifo],vector3_[iv])/gs;
}
else {
SpinorBarWaveFunction spinorBarInter =
incomingVertex_[inter]->evaluate(scale,3,inpart.dataPtr(),wavebar3_[ifi],
gluon_[2*ig],inpart.mass());
if (wavebar3_[ifi].particle()->PDGName()!=spinorBarInter.particle()->PDGName())
throw Exception()
<< wavebar3_[ifi].particle()->PDGName() << " was changed to "
<< spinorBarInter.particle()->PDGName() << " in FFVDecayer::threeBodyME"
<< Exception::runerror;
diag = vertex_->evaluate(scale,wave3_[ifo], spinorBarInter,vector3_[iv])/gs;
}
for(unsigned int ix=0;ix<colourFlow[0].size();++ix) {
(*ME[colourFlow[0][ix].first])(ifi, ifo, iv, ig) +=
colourFlow[0][ix].second*diag;
}
}
// radiation from outgoing fermion
if(decay[iferm]->dataPtr()->coloured()) {
assert(outgoingVertexF_[inter]);
// ensure you get correct outgoing particle from first vertex
tcPDPtr off = decay[iferm]->dataPtr();
if(off->CC()) off = off->CC();
double gs = outgoingVertexF_[inter]->strongCoupling(scale);
if (ferm) {
SpinorBarWaveFunction spinorBarInter =
outgoingVertexF_[inter]->evaluate(scale,3,off,wavebar3_[ifo],
gluon_[2*ig],decay[iferm]->mass());
if(wavebar3_[ifo].particle()->PDGName()!=spinorBarInter.particle()->PDGName())
throw Exception()
<< wavebar3_[ifo].particle()->PDGName() << " was changed to "
<< spinorBarInter.particle()->PDGName() << " in FFVDecayer::threeBodyME"
<< Exception::runerror;
diag = vertex_->evaluate(scale,wave3_[ifi],spinorBarInter,vector3_[iv])/gs;
}
else {
SpinorWaveFunction spinorInter =
outgoingVertexF_[inter]->evaluate(scale,3,off,wave3_[ifo],
gluon_[2*ig],decay[iferm]->mass());
if(wave3_[ifo].particle()->PDGName()!=spinorInter.particle()->PDGName())
throw Exception()
<< wave3_[ifo].particle()->PDGName() << " was changed to "
<< spinorInter.particle()->PDGName() << " in FFVDecayer::threeBodyME"
<< Exception::runerror;
diag = vertex_->evaluate(scale,spinorInter,wavebar3_[ifi],vector3_[iv])/gs;
}
for(unsigned int ix=0;ix<colourFlow[F].size();++ix) {
(*ME[colourFlow[F][ix].first])(ifi, ifo, iv, ig) +=
colourFlow[F][ix].second*diag;
}
}
// radiation from outgoing vector
if(decay[ivect]->dataPtr()->coloured()) {
assert(outgoingVertexV_[inter]);
// ensure you get correct ougoing particle from first vertex
tcPDPtr off = decay[ivect]->dataPtr();
if(off->CC()) off = off->CC();
double sign = decay[iferm]->id()>0 ? -1:1;
double gs = outgoingVertexV_[inter]->strongCoupling(scale);
VectorWaveFunction vectorInter =
outgoingVertexV_[inter]->evaluate(scale,3,off,gluon_[2*ig],
vector3_[iv],decay[ivect]->mass());
if(vector3_[iv].particle()->PDGName()!=vectorInter.particle()->PDGName())
throw Exception()
<< vector3_[iv].particle()->PDGName() << " was changed to "
<< vectorInter. particle()->PDGName() << " in FFVDecayer::threeBodyME"
<< Exception::runerror;
if (ferm){
diag = sign*vertex_->evaluate(scale,wave3_[ifi],wavebar3_[ifo],vectorInter)/gs;
}
else {
diag = sign*vertex_->evaluate(scale,wave3_[ifo],wavebar3_[ifi],vectorInter)/gs;
}
for(unsigned int ix=0;ix<colourFlow[V].size();++ix) {
(*ME[colourFlow[V][ix].first])(ifi, ifo, iv, ig) +=
colourFlow[V][ix].second*diag;
}
}
}
if(massless) ++iv;
}
}
}
// contract matrices
double output=0.;
for(unsigned int ix=0; ix<nflow; ++ix){
for(unsigned int iy=0; iy<nflow; ++iy){
output+=cfactors[ix][iy]*(ME[ix]->contract(*ME[iy],rho3_)).real();
}
}
output*=(4.*Constants::pi);
// return the answer
return output;
}
diff --git a/Decay/General/GeneralTwoBodyDecayer.cc b/Decay/General/GeneralTwoBodyDecayer.cc
--- a/Decay/General/GeneralTwoBodyDecayer.cc
+++ b/Decay/General/GeneralTwoBodyDecayer.cc
@@ -1,719 +1,708 @@
// -*- C++ -*-
//
// GeneralTwoBodyDecayer.cc is a part of Herwig - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2017 The Herwig Collaboration
//
// Herwig is licenced under version 3 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 GeneralTwoBodyDecayer class.
//
#include "GeneralTwoBodyDecayer.h"
#include "ThePEG/Utilities/DescribeClass.h"
#include "ThePEG/Interface/ClassDocumentation.h"
#include "ThePEG/Persistency/PersistentOStream.h"
#include "ThePEG/Persistency/PersistentIStream.h"
#include "ThePEG/PDT/DecayMode.h"
#include "ThePEG/Utilities/Exception.h"
#include "Herwig/Shower/RealEmissionProcess.h"
using namespace Herwig;
ParticleVector GeneralTwoBodyDecayer::decay(const Particle & parent,
const tPDVector & children) const {
// return empty vector if products heavier than parent
Energy mout(ZERO);
for(tPDVector::const_iterator it=children.begin();
it!=children.end();++it) mout+=(**it).massMin();
if(mout>parent.mass()) return ParticleVector();
// generate the decay
bool cc;
int imode=modeNumber(cc,parent.dataPtr(),children);
// generate the kinematics
ParticleVector decay=generate(generateIntermediates(),cc,imode,parent);
// make the colour connections
colourConnections(parent, decay);
// return the answer
return decay;
}
void GeneralTwoBodyDecayer::doinit() {
PerturbativeDecayer::doinit();
assert( incoming_ && outgoing_.size()==2);
//create phase space mode
tPDVector extpart(3);
extpart[0] = incoming_;
extpart[1] = outgoing_[0];
extpart[2] = outgoing_[1];
addMode(new_ptr(DecayPhaseSpaceMode(extpart, this)), maxWeight_, vector<double>());
}
int GeneralTwoBodyDecayer::modeNumber(bool & cc, tcPDPtr parent,
const tPDVector & children) const {
long parentID = parent->id();
long id1 = children[0]->id();
long id2 = children[1]->id();
cc = false;
long out1 = outgoing_[0]->id();
long out2 = outgoing_[1]->id();
if( parentID == incoming_->id() &&
((id1 == out1 && id2 == out2) ||
(id1 == out2 && id2 == out1)) ) {
return 0;
}
else if(incoming_->CC() && parentID == incoming_->CC()->id()) {
cc = true;
if( outgoing_[0]->CC()) out1 = outgoing_[0]->CC()->id();
if( outgoing_[1]->CC()) out2 = outgoing_[1]->CC()->id();
if((id1 == out1 && id2 == out2) ||
(id1 == out2 && id2 == out1)) return 0;
}
return -1;
}
void GeneralTwoBodyDecayer::
colourConnections(const Particle & parent,
const ParticleVector & out) const {
PDT::Colour incColour(parent.data().iColour());
PDT::Colour outaColour(out[0]->data().iColour());
PDT::Colour outbColour(out[1]->data().iColour());
//incoming colour singlet
if(incColour == PDT::Colour0) {
// colour triplet-colourantitriplet
if((outaColour == PDT::Colour3 && outbColour == PDT::Colour3bar) ||
(outaColour == PDT::Colour3bar && outbColour == PDT::Colour3)) {
bool ac(out[0]->id() < 0);
out[0]->colourNeighbour(out[1],!ac);
}
//colour octet
else if(outaColour == PDT::Colour8 && outbColour == PDT::Colour8) {
out[0]->colourNeighbour(out[1]);
out[0]->antiColourNeighbour(out[1]);
}
// colour singlets
else if(outaColour == PDT::Colour0 && outbColour == PDT::Colour0) {
}
// unknown
else
throw Exception() << "Unknown outgoing colours for decaying "
<< "colour singlet in "
<< "GeneralTwoBodyDecayer::colourConnections "
<< outaColour << " " << outbColour
<< Exception::runerror;
}
//incoming colour triplet
else if(incColour == PDT::Colour3) {
// colour triplet + singlet
if(outaColour == PDT::Colour3 && outbColour == PDT::Colour0) {
out[0]->incomingColour(const_ptr_cast<tPPtr>(&parent));
}
//opposite order
else if(outaColour == PDT::Colour0 && outbColour == PDT::Colour3) {
out[1]->incomingColour(const_ptr_cast<tPPtr>(&parent));
}
// octet + triplet
else if(outaColour == PDT::Colour8 && outbColour == PDT::Colour3) {
out[0]->incomingColour(const_ptr_cast<tPPtr>(&parent));
out[1]->antiColourNeighbour(out[0]);
}
//opposite order
else if(outaColour == PDT::Colour3 && outbColour == PDT::Colour8) {
out[1]->incomingColour(const_ptr_cast<tPPtr>(&parent));
out[0]->antiColourNeighbour(out[1]);
}
else if(outaColour == PDT::Colour3bar && outaColour == PDT::Colour3bar) {
tColinePtr col[2] = {ColourLine::create(out[0],true),
ColourLine::create(out[1],true)};
parent.colourLine()->setSinkNeighbours(col[0],col[1]);
}
else
throw Exception() << "Unknown outgoing colours for decaying "
<< "colour triplet in "
<< "GeneralTwoBodyDecayer::colourConnections() "
<< outaColour << " " << outbColour
<< Exception::runerror;
}
// incoming colour anti triplet
else if(incColour == PDT::Colour3bar) {
// colour antitriplet +singlet
if(outaColour == PDT::Colour3bar && outbColour == PDT::Colour0) {
out[0]->incomingAntiColour(const_ptr_cast<tPPtr>(&parent));
}
//opposite order
else if(outaColour == PDT::Colour0 && outbColour == PDT::Colour3bar) {
out[1]->incomingAntiColour(const_ptr_cast<tPPtr>(&parent));
}
//octet + antitriplet
else if(outaColour == PDT::Colour3bar && outbColour == PDT::Colour8) {
out[1]->incomingAntiColour(const_ptr_cast<tPPtr>(&parent));
out[0]->colourNeighbour(out[1]);
}
//opposite order
else if(outaColour == PDT::Colour8 && outbColour == PDT::Colour3bar) {
out[0]->incomingAntiColour(const_ptr_cast<tPPtr>(&parent));
out[1]->colourNeighbour(out[0]);
}
else if(outaColour == PDT::Colour3 && outbColour == PDT::Colour3) {
tColinePtr col[2] = {ColourLine::create(out[0]),
ColourLine::create(out[1])};
parent.antiColourLine()->setSourceNeighbours(col[0],col[1]);
}
else
throw Exception() << "Unknown outgoing colours for decaying "
<< "colour antitriplet "
<< "in GeneralTwoBodyDecayer::colourConnections() "
<< outaColour << " " << outbColour
<< Exception::runerror;
}
//incoming colour octet
else if(incColour == PDT::Colour8) {
// triplet-antitriplet
if(outaColour == PDT::Colour3&&outbColour == PDT::Colour3bar) {
out[0]->incomingColour(const_ptr_cast<tPPtr>(&parent));
out[1]->incomingAntiColour(const_ptr_cast<tPPtr>(&parent));
}
// opposite order
else if(outbColour == PDT::Colour3&&outaColour == PDT::Colour3bar) {
out[0]->incomingAntiColour(const_ptr_cast<tPPtr>(&parent));
out[1]->incomingColour(const_ptr_cast<tPPtr>(&parent));
}
// neutral octet
else if(outaColour == PDT::Colour0&&outbColour == PDT::Colour8) {
out[1]->incomingColour(const_ptr_cast<tPPtr>(&parent));
out[1]->incomingAntiColour(const_ptr_cast<tPPtr>(&parent));
}
else if(outbColour == PDT::Colour0&&outaColour == PDT::Colour8) {
out[0]->incomingColour(const_ptr_cast<tPPtr>(&parent));
out[0]->incomingAntiColour(const_ptr_cast<tPPtr>(&parent));
}
else
throw Exception() << "Unknown outgoing colours for decaying "
<< "colour octet "
<< "in GeneralTwoBodyDecayer::colourConnections() "
<< outaColour << " " << outbColour
<< Exception::runerror;
}
else if(incColour == PDT::Colour6) {
if(outaColour == PDT::Colour3 && outbColour == PDT::Colour3) {
tPPtr tempParent = const_ptr_cast<tPPtr>(&parent);
Ptr<MultiColour>::pointer parentColour =
dynamic_ptr_cast<Ptr<MultiColour>::pointer>
(tempParent->colourInfo());
tColinePtr line1 = const_ptr_cast<tColinePtr>(parentColour->colourLines()[0]);
line1->addColoured(dynamic_ptr_cast<tPPtr>(out[0]));
tColinePtr line2 = const_ptr_cast<tColinePtr>(parentColour->colourLines()[1]);
line2->addColoured(dynamic_ptr_cast<tPPtr>(out[1]));
}
else
throw Exception() << "Unknown outgoing colours for decaying "
<< "colour sextet "
<< "in GeneralTwoBodyDecayer::colourConnections() "
<< outaColour << " " << outbColour
<< Exception::runerror;
}
else if(incColour == PDT::Colour6bar) {
if(outaColour == PDT::Colour3bar && outbColour == PDT::Colour3bar) {
tPPtr tempParent = const_ptr_cast<tPPtr>(&parent);
Ptr<MultiColour>::pointer parentColour =
dynamic_ptr_cast<Ptr<MultiColour>::pointer>
(tempParent->colourInfo());
tColinePtr line1 = const_ptr_cast<tColinePtr>(parentColour->antiColourLines()[0]);
line1->addAntiColoured(dynamic_ptr_cast<tPPtr>(out[0]));
tColinePtr line2 = const_ptr_cast<tColinePtr>(parentColour->antiColourLines()[1]);
line2->addAntiColoured(dynamic_ptr_cast<tPPtr>(out[1]));
}
else
throw Exception() << "Unknown outgoing colours for decaying "
<< "colour anti-sextet "
<< "in GeneralTwoBodyDecayer::colourConnections() "
<< outaColour << " " << outbColour
<< Exception::runerror;
}
else
throw Exception() << "Unknown incoming colour in "
<< "GeneralTwoBodyDecayer::colourConnections() "
<< incColour
<< Exception::runerror;
}
bool GeneralTwoBodyDecayer::twoBodyMEcode(const DecayMode & dm, int & mecode,
double & coupling) const {
assert(dm.parent()->id() == incoming_->id());
ParticleMSet::const_iterator pit = dm.products().begin();
long id1 = (*pit)->id();
++pit;
long id2 = (*pit)->id();
long id1t(outgoing_[0]->id()), id2t(outgoing_[1]->id());
mecode = -1;
coupling = 1.;
if( id1 == id1t && id2 == id2t ) {
return true;
}
else if( id1 == id2t && id2 == id1t ) {
return false;
}
else
assert(false);
return false;
}
void GeneralTwoBodyDecayer::persistentOutput(PersistentOStream & os) const {
os << incoming_ << outgoing_ << maxWeight_;
}
void GeneralTwoBodyDecayer::persistentInput(PersistentIStream & is, int) {
is >> incoming_ >> outgoing_ >> maxWeight_;
}
// The following static variable is needed for the type
// description system in ThePEG.
DescribeAbstractClass<GeneralTwoBodyDecayer,PerturbativeDecayer>
describeHerwigGeneralTwoBodyDecayer("Herwig::GeneralTwoBodyDecayer", "Herwig.so");
void GeneralTwoBodyDecayer::Init() {
static ClassDocumentation<GeneralTwoBodyDecayer> documentation
("This class is designed to be a base class for all 2 body decays"
"in a general model");
}
double GeneralTwoBodyDecayer::brat(const DecayMode &, const Particle & p,
double oldbrat) const {
ParticleVector children = p.children();
if( children.size() != 2 || !p.data().widthGenerator() )
return oldbrat;
// partial width for this mode
Energy scale = p.mass();
Energy pwidth =
partialWidth( make_pair(p.dataPtr(), scale),
make_pair(children[0]->dataPtr(), children[0]->mass()),
make_pair(children[1]->dataPtr(), children[1]->mass()) );
Energy width = p.data().widthGenerator()->width(p.data(), scale);
return pwidth/width;
}
void GeneralTwoBodyDecayer::doinitrun() {
PerturbativeDecayer::doinitrun();
for(unsigned int ix=0;ix<numberModes();++ix) {
double fact = pow(1.5,int(mode(ix)->externalParticles(0)->iSpin())-1);
mode(ix)->setMaxWeight(fact*mode(ix)->maxWeight());
}
}
double GeneralTwoBodyDecayer::colourFactor(tcPDPtr in, tcPDPtr out1,
tcPDPtr out2) const {
// identical particle symmetry factor
double output = out1->id()==out2->id() ? 0.5 : 1.;
// colour neutral incoming particle
if(in->iColour()==PDT::Colour0) {
// both colour neutral
if(out1->iColour()==PDT::Colour0 && out2->iColour()==PDT::Colour0)
output *= 1.;
// colour triplet/ antitriplet
else if((out1->iColour()==PDT::Colour3 && out2->iColour()==PDT::Colour3bar) ||
(out1->iColour()==PDT::Colour3bar && out2->iColour()==PDT::Colour3 ) ) {
output *= 3.;
}
// colour octet colour octet
else if(out1->iColour()==PDT::Colour8 && out2->iColour()==PDT::Colour8 ) {
output *= 8.;
}
else
throw Exception() << "Unknown colour for the outgoing particles"
<< " for decay colour neutral particle in "
<< "GeneralTwoBodyDecayer::colourFactor() for "
<< in->PDGName() << " -> "
<< out1->PDGName() << " " << out2->PDGName()
<< Exception::runerror;
}
// triplet
else if(in->iColour()==PDT::Colour3) {
// colour triplet + neutral
if((out1->iColour()==PDT::Colour0 && out2->iColour()==PDT::Colour3) ||
(out1->iColour()==PDT::Colour3 && out2->iColour()==PDT::Colour0) ) {
output *= 1.;
}
// colour triplet + octet
else if((out1->iColour()==PDT::Colour8 && out2->iColour()==PDT::Colour3) ||
(out1->iColour()==PDT::Colour3 && out2->iColour()==PDT::Colour8) ) {
output *= 4./3.;
}
// colour anti triplet anti triplet
else if(out1->iColour()==PDT::Colour3bar &&
out2->iColour()==PDT::Colour3bar) {
output *= 2.;
}
else
throw Exception() << "Unknown colour for the outgoing particles"
<< " for decay colour triplet particle in "
<< "GeneralTwoBodyDecayer::colourFactor() for "
<< in->PDGName() << " -> "
<< out1->PDGName() << " " << out2->PDGName()
<< Exception::runerror;
}
// anti triplet
else if(in->iColour()==PDT::Colour3bar) {
// colour anti triplet + neutral
if((out1->iColour()==PDT::Colour0 && out2->iColour()==PDT::Colour3bar ) ||
(out1->iColour()==PDT::Colour3bar && out2->iColour()==PDT::Colour0 ) ) {
output *= 1.;
}
// colour anti triplet + octet
else if((out1->iColour()==PDT::Colour8 && out2->iColour()==PDT::Colour3bar ) ||
(out1->iColour()==PDT::Colour3bar && out2->iColour()==PDT::Colour8 ) ) {
output *= 4./3.;
}
// colour triplet triplet
else if(out1->iColour()==PDT::Colour3 &&
out2->iColour()==PDT::Colour3) {
output *= 2.;
}
else
throw Exception() << "Unknown colour for the outgoing particles"
<< " for decay colour anti triplet particle in "
<< "GeneralTwoBodyDecayer::colourFactor() for "
<< in->PDGName() << " -> "
<< out1->PDGName() << " " << out2->PDGName()
<< Exception::runerror;
}
else if(in->iColour()==PDT::Colour8) {
// colour octet + neutral
if((out1->iColour()==PDT::Colour0 && out2->iColour()==PDT::Colour8 ) ||
(out1->iColour()==PDT::Colour8 && out2->iColour()==PDT::Colour0 ) ) {
output *= 1.;
}
// colour triplet/antitriplet
else if((out1->iColour()==PDT::Colour3 && out2->iColour()==PDT::Colour3bar) ||
(out1->iColour()==PDT::Colour3bar && out2->iColour()==PDT::Colour3 ) ) {
output *= 0.5;
}
else
throw Exception() << "Unknown colour for the outgoing particles"
<< " for decay colour octet particle in "
<< "GeneralTwoBodyDecayer::colourFactor() for "
<< in->PDGName() << " -> "
<< out1->PDGName() << " " << out2->PDGName()
<< Exception::runerror;
}
else if(in->iColour()==PDT::Colour6) {
// colour sextet -> triplet triplet
if( out1->iColour()==PDT::Colour3 && out2->iColour()==PDT::Colour3 ) {
output *= 1.;
}
else
throw Exception() << "Unknown colour for the outgoing particles"
<< " for decay colour sextet particle in "
<< "GeneralTwoBodyDecayer::colourFactor() for "
<< in->PDGName() << " -> "
<< out1->PDGName() << " " << out2->PDGName()
<< Exception::runerror;
}
else if(in->iColour()==PDT::Colour6bar) {
// colour sextet -> triplet triplet
if( out1->iColour()==PDT::Colour3bar && out2->iColour()==PDT::Colour3bar ) {
output *= 1.;
}
else
throw Exception() << "Unknown colour for the outgoing particles"
<< " for decay colour anti-sextet particle in "
<< "GeneralTwoBodyDecayer::colourFactor() for "
<< in->PDGName() << " -> "
<< out1->PDGName() << " " << out2->PDGName()
<< Exception::runerror;
}
else
throw Exception() << "Unknown colour "
<< in->iColour() << " for the decaying particle in "
<< "GeneralTwoBodyDecayer::colourFactor() for "
<< in->PDGName() << " -> "
<< out1->PDGName() << " " << out2->PDGName()
<< Exception::runerror;
return output;
}
Energy GeneralTwoBodyDecayer::partialWidth(PMPair inpart, PMPair outa,
PMPair outb) const {
// select the number of the mode
tPDVector children;
children.push_back(const_ptr_cast<PDPtr>(outa.first));
children.push_back(const_ptr_cast<PDPtr>(outb.first));
bool cc;
int nmode=modeNumber(cc,inpart.first,children);
tcPDPtr newchild[2] = {mode(nmode)->externalParticles(1),
mode(nmode)->externalParticles(2)};
// make the particles
Lorentz5Momentum pparent = Lorentz5Momentum(inpart.second);
PPtr parent = inpart.first->produceParticle(pparent);
Lorentz5Momentum pout[2];
double ctheta,phi;
Kinematics::generateAngles(ctheta,phi);
Kinematics::twoBodyDecay(pparent, outa.second, outb.second,
ctheta, phi,pout[0],pout[1]);
if( ( !cc && outa.first!=newchild[0]) ||
( cc && !(( outa.first->CC() && outa.first->CC() == newchild[0])||
( !outa.first->CC() && outa.first == newchild[0]) )))
swap(pout[0],pout[1]);
ParticleVector decay;
decay.push_back(newchild[0]->produceParticle(pout[0]));
decay.push_back(newchild[1]->produceParticle(pout[1]));
double me = me2(-1,*parent,decay,Initialize);
Energy pcm = Kinematics::pstarTwoBodyDecay(inpart.second,
outa.second, outb.second);
return me/(8.*Constants::pi)*pcm;
}
void GeneralTwoBodyDecayer::decayInfo(PDPtr incoming, PDPair outgoing) {
incoming_=incoming;
outgoing_.clear();
outgoing_.push_back(outgoing.first );
outgoing_.push_back(outgoing.second);
}
double GeneralTwoBodyDecayer::matrixElementRatio(const Particle & inpart,
const ParticleVector & decay2,
const ParticleVector & decay3,
MEOption meopt,
ShowerInteraction inter) {
// calculate R/B
double B = me2 (0, inpart, decay2, meopt);
double R = threeBodyME(0, inpart, decay3, inter, meopt);
return R/B;
}
const vector<DVector> & GeneralTwoBodyDecayer::getColourFactors(const Particle & inpart,
const ParticleVector & decay,
unsigned int & nflow){
// calculate the colour factors for the three-body decay
vector<int> sing,trip,atrip,oct;
for(unsigned int it=0;it<decay.size();++it) {
if (decay[it]->dataPtr()->iColour() == PDT::Colour0 ) sing. push_back(it);
else if(decay[it]->dataPtr()->iColour() == PDT::Colour3 ) trip. push_back(it);
else if(decay[it]->dataPtr()->iColour() == PDT::Colour3bar ) atrip.push_back(it);
else if(decay[it]->dataPtr()->iColour() == PDT::Colour8 ) oct. push_back(it);
}
// require at least one gluon
assert(oct.size()>=1);
// identical particle symmetry factor
double symFactor=1.;
if (( sing.size()==2 && decay[ sing[0]]->id()==decay[ sing[1]]->id()) ||
( trip.size()==2 && decay[ trip[0]]->id()==decay[ trip[1]]->id()) ||
(atrip.size()==2 && decay[atrip[0]]->id()==decay[atrip[1]]->id()) ||
( oct.size()==2 && decay[ oct[0]]->id()==decay[ oct[1]]->id()))
symFactor/=2.;
else if (oct.size()==3 &&
decay[oct[0]]->id()==decay[oct[1]]->id() &&
decay[oct[0]]->id()==decay[oct[2]]->id())
symFactor/=6.;
colour_ = vector<DVector>(1,DVector(1,symFactor*1.));
// decaying colour singlet
if(inpart.dataPtr()->iColour() == PDT::Colour0) {
if(trip.size()==1 && atrip.size()==1 && oct.size()==1) {
nflow = 1;
colour_ = vector<DVector>(1,DVector(1,symFactor*4.));
}
else if (oct.size()==3){
nflow = 1.;
colour_ = vector<DVector>(1,DVector(1,symFactor*24.));
}
else
throw Exception() << "Unknown colour for the outgoing particles"
<< " for decay colour scalar particle in "
<< "GeneralTwoBodyDecayer::getColourFactors() for "
<< inpart. dataPtr()->PDGName() << " -> "
<< decay[0]->dataPtr()->PDGName() << " "
<< decay[1]->dataPtr()->PDGName() << " "
<< decay[2]->dataPtr()->PDGName()
<< Exception::runerror;
}
// decaying colour triplet
else if(inpart.dataPtr()->iColour() == PDT::Colour3) {
if(trip.size()==1 && sing.size()==1 && oct.size()==1) {
nflow = 1;
colour_ = vector<DVector>(1,DVector(1,symFactor*4./3.));
}
else if(trip.size()==1 && oct.size()==2) {
nflow = 2;
colour_.clear();
colour_.resize(2,DVector(2,0.));
colour_[0][0] = symFactor*16./9.; colour_[0][1] = -symFactor*2./9.;
colour_[1][0] = -symFactor*2./9.; colour_[1][1] = symFactor*16./9.;
}
else
throw Exception() << "Unknown colour for the outgoing particles"
<< " for decay colour triplet particle in "
<< "GeneralTwoBodyDecayer::getColourFactors() for "
<< inpart. dataPtr()->PDGName() << " -> "
<< decay[0]->dataPtr()->PDGName() << " "
<< decay[1]->dataPtr()->PDGName() << " "
<< decay[2]->dataPtr()->PDGName()
<< Exception::runerror;
}
// decaying colour anti-triplet
else if(inpart.dataPtr()->iColour() == PDT::Colour3bar) {
if(atrip.size()==1 && sing.size()==1 && oct.size()==1) {
nflow = 1;
colour_ = vector<DVector>(1,DVector(1,symFactor*4./3.));
}
else if(atrip.size()==1 && oct.size()==2){
nflow = 2;
colour_.clear();
colour_ .resize(2,DVector(2,0.));
colour_[0][0] = symFactor*16./9.; colour_[0][1] = -symFactor*2./9.;
colour_[1][0] = -symFactor*2./9.; colour_[1][1] = symFactor*16./9.;
}
else
throw Exception() << "Unknown colour for the outgoing particles"
<< " for decay colour anti-triplet particle in "
<< "GeneralTwoBodyDecayer::getColourFactors() for "
<< inpart. dataPtr()->PDGName() << " -> "
<< decay[0]->dataPtr()->PDGName() << " "
<< decay[1]->dataPtr()->PDGName() << " "
<< decay[2]->dataPtr()->PDGName()
<< Exception::runerror;
}
// decaying colour octet
else if(inpart.dataPtr()->iColour() == PDT::Colour8) {
if(oct.size()==1 && trip.size()==1 && atrip.size()==1) {
nflow = 2;
colour_.clear();
colour_.resize(2,DVector(2,0.));
colour_[0][0] = symFactor*2./3. ; colour_[0][1] = -symFactor*1./12.;
colour_[1][0] = -symFactor*1./12.; colour_[1][1] = symFactor*2./3. ;
}
else if (oct.size()==2 && sing.size()==1){
nflow = 1;
colour_ = vector<DVector>(1,DVector(1,symFactor*3.));
}
else
throw Exception() << "Unknown colour for the outgoing particles"
<< " for decay colour octet particle in "
<< "GeneralTwoBodyDecayer::getColourFactors() for "
<< inpart. dataPtr()->PDGName() << " -> "
<< decay[0]->dataPtr()->PDGName() << " "
<< decay[1]->dataPtr()->PDGName() << " "
<< decay[2]->dataPtr()->PDGName()
<< Exception::runerror;
}
else
throw Exception() << "Unknown colour for the decaying particle in "
<< "GeneralTwoBodyDecayer::getColourFactors() for "
<< inpart. dataPtr()->PDGName() << " -> "
<< decay[0]->dataPtr()->PDGName() << " "
<< decay[1]->dataPtr()->PDGName() << " "
<< decay[2]->dataPtr()->PDGName()
<< Exception::runerror;
return colour_;
}
const GeneralTwoBodyDecayer::CFlow &
GeneralTwoBodyDecayer::colourFlows(const Particle & inpart,
const ParticleVector & decay) {
// static initialization of commonly used colour structures
static const CFlow init = CFlow(3, CFlowPairVec(1, make_pair(0, 1.)));
static CFlow tripflow = init;
static CFlow atripflow = init;
static CFlow octflow = init;
static const CFlow fpflow = CFlow(4, CFlowPairVec(1, make_pair(0, 1.)));
static bool initialized = false;
if (! initialized) {
tripflow[2].resize(2, make_pair(0,1.));
tripflow[2][0] = make_pair(0, 1.);
tripflow[2][1] = make_pair(1,-1.);
tripflow[1][0] = make_pair(1, 1.);
atripflow[1].resize(2, make_pair(0,1.));
atripflow[1][0] = make_pair(0, 1.);
atripflow[1][1] = make_pair(1,-1.);
atripflow[2][0] = make_pair(1, 1.);
octflow[0].resize(2, make_pair(0,1.));
octflow[0][0] = make_pair(0,-1.);
octflow[0][1] = make_pair(1, 1.);
octflow[2][0] = make_pair(1, 1.);
initialized = true;
}
// main function body
int sing=0,trip=0,atrip=0,oct=0;
for (size_t it=0; it<decay.size(); ++it) {
switch ( decay[it]->dataPtr()->iColour() ) {
case PDT::Colour0: ++sing; break;
case PDT::Colour3: ++trip; break;
case PDT::Colour3bar: ++atrip; break;
case PDT::Colour8: ++oct; break;
/// @todo: handle these better
case PDT::ColourUndefined: break;
case PDT::Coloured: break;
case PDT::Colour6: break;
case PDT::Colour6bar: break;
}
}
// require a gluon
assert(oct>=1);
const CFlow * retval = 0;
bool inconsistent4PV = true;
// decaying colour triplet
if(inpart.dataPtr()->iColour() == PDT::Colour3 &&
trip==1 && oct==2) {
retval = &tripflow;
}
// decaying colour anti-triplet
else if(inpart.dataPtr()->iColour() == PDT::Colour3bar &&
atrip==1 && oct==2){
retval = &atripflow;
}
// decaying colour octet
else if(inpart.dataPtr()->iColour() == PDT::Colour8 &&
oct==1 && trip==1 && atrip==1) {
retval = &octflow;
}
else {
inconsistent4PV = false;
- retval = &init;
+ retval = &fpflow;
}
-
- // // if a 4 point vertex exists, add a colour flow for it
- // if ( fourPointVertex_.find(ShowerInteraction::QCD)!=fourPointVertex_.end() ) {
- // if ( inconsistent4PV )
- // throw Exception() << "Unknown colour flows for 4 point vertex in "
- // << "GeneralTwoBodyDecayer::colourFlows()"
- // << Exception::runerror;
- // else {
- // retval = &fpflow;
- // }
- // }
return *retval;
}
double GeneralTwoBodyDecayer::threeBodyME(const int , const Particle &,
const ParticleVector &,
ShowerInteraction, MEOption) {
throw Exception() << "Base class PerturbativeDecayer::threeBodyME() "
<< "called, should have an implementation in the inheriting class"
<< Exception::runerror;
return 0.;
}
diff --git a/Decay/General/SSVDecayer.cc b/Decay/General/SSVDecayer.cc
--- a/Decay/General/SSVDecayer.cc
+++ b/Decay/General/SSVDecayer.cc
@@ -1,333 +1,339 @@
// -*- C++ -*-
//
// SSVDecayer.cc is a part of Herwig - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2017 The Herwig Collaboration
//
// Herwig is licenced under version 3 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 SSVDecayer class.
//
#include "SSVDecayer.h"
#include "ThePEG/Utilities/DescribeClass.h"
#include "ThePEG/Interface/ClassDocumentation.h"
#include "ThePEG/Persistency/PersistentOStream.h"
#include "ThePEG/Persistency/PersistentIStream.h"
#include "ThePEG/PDT/DecayMode.h"
#include "Herwig/Utilities/Kinematics.h"
#include "ThePEG/Helicity/WaveFunction/ScalarWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/VectorWaveFunction.h"
#include "Herwig/Decay/GeneralDecayMatrixElement.h"
using namespace Herwig;
using namespace ThePEG::Helicity;
IBPtr SSVDecayer::clone() const {
return new_ptr(*this);
}
IBPtr SSVDecayer::fullclone() const {
return new_ptr(*this);
}
void SSVDecayer::setDecayInfo(PDPtr incoming, PDPair outgoing,
VertexBasePtr vertex,
map<ShowerInteraction,VertexBasePtr> & inV,
const vector<map<ShowerInteraction,VertexBasePtr> > & outV,
map<ShowerInteraction,VertexBasePtr> fourV) {
decayInfo(incoming,outgoing);
vertex_ = dynamic_ptr_cast<AbstractVSSVertexPtr>(vertex);
perturbativeVertex_ = dynamic_ptr_cast<VSSVertexPtr> (vertex);
vector<ShowerInteraction> itemp={ShowerInteraction::QCD,ShowerInteraction::QED};
for(auto & inter : itemp) {
incomingVertex_[inter] = dynamic_ptr_cast<AbstractVSSVertexPtr>(inV.at(inter));
fourPointVertex_[inter] = dynamic_ptr_cast<AbstractVVSSVertexPtr>(fourV.at(inter));
- if (outV[0].at(inter)->getName()==VertexType::VSS){
- outgoingVertexS_[inter] = dynamic_ptr_cast<AbstractVSSVertexPtr>(outV[0].at(inter));
- outgoingVertexV_[inter] = dynamic_ptr_cast<AbstractVVVVertexPtr>(outV[1].at(inter));
+ outgoingVertexS_[inter] = AbstractVSSVertexPtr();
+ outgoingVertexV_[inter] = AbstractVVVVertexPtr();
+ if(outV[0].at(inter)) {
+ if (outV[0].at(inter)->getName()==VertexType::VSS)
+ outgoingVertexS_[inter] = dynamic_ptr_cast<AbstractVSSVertexPtr>(outV[0].at(inter));
+ else
+ outgoingVertexV_[inter] = dynamic_ptr_cast<AbstractVVVVertexPtr>(outV[0].at(inter));
}
- else {
- outgoingVertexS_[inter] = dynamic_ptr_cast<AbstractVSSVertexPtr>(outV[1].at(inter));
- outgoingVertexV_[inter] = dynamic_ptr_cast<AbstractVVVVertexPtr>(outV[0].at(inter));
+ if(outV[1].at(inter)) {
+ if (outV[1].at(inter)->getName()==VertexType::VSS)
+ outgoingVertexS_[inter] = dynamic_ptr_cast<AbstractVSSVertexPtr>(outV[1].at(inter));
+ else
+ outgoingVertexV_[inter] = dynamic_ptr_cast<AbstractVVVVertexPtr>(outV[1].at(inter));
}
}
}
void SSVDecayer::persistentOutput(PersistentOStream & os) const {
os << vertex_ << perturbativeVertex_
<< incomingVertex_ << outgoingVertexS_
<< outgoingVertexV_ << fourPointVertex_;
}
void SSVDecayer::persistentInput(PersistentIStream & is, int) {
is >> vertex_ >> perturbativeVertex_
>> incomingVertex_ >> outgoingVertexS_
>> outgoingVertexV_ >> fourPointVertex_;
}
// The following static variable is needed for the type
// description system in ThePEG.
DescribeClass<SSVDecayer,GeneralTwoBodyDecayer>
describeHerwigSSVDecayer("Herwig::SSVDecayer", "Herwig.so");
void SSVDecayer::Init() {
static ClassDocumentation<SSVDecayer> documentation
("This implements the decay of a scalar to a vector and a scalar");
}
double SSVDecayer::me2(const int , const Particle & inpart,
const ParticleVector & decay,
MEOption meopt) const {
unsigned int isc(0),ivec(1);
if(decay[0]->dataPtr()->iSpin() != PDT::Spin0) swap(isc,ivec);
if(!ME()) {
if(ivec==1)
ME(new_ptr(GeneralDecayMatrixElement(PDT::Spin0,PDT::Spin0,PDT::Spin1)));
else
ME(new_ptr(GeneralDecayMatrixElement(PDT::Spin0,PDT::Spin1,PDT::Spin0)));
}
if(meopt==Initialize) {
ScalarWaveFunction::
calculateWaveFunctions(rho_,const_ptr_cast<tPPtr>(&inpart),incoming);
swave_ = ScalarWaveFunction(inpart.momentum(),inpart.dataPtr(),incoming);
}
if(meopt==Terminate) {
ScalarWaveFunction::
constructSpinInfo(const_ptr_cast<tPPtr>(&inpart),incoming,true);
ScalarWaveFunction::
constructSpinInfo(decay[isc],outgoing,true);
VectorWaveFunction::
constructSpinInfo(vector_,decay[ivec],outgoing,true,false);
}
VectorWaveFunction::
calculateWaveFunctions(vector_,decay[ivec],outgoing,false);
ScalarWaveFunction sca(decay[isc]->momentum(),decay[isc]->dataPtr(),outgoing);
Energy2 scale(sqr(inpart.mass()));
//make sure decay matrix element is in the correct order
double output(0.);
if(ivec == 0) {
for(unsigned int ix = 0; ix < 3; ++ix)
(*ME())(0, ix, 0) = vertex_->evaluate(scale,vector_[ix],sca, swave_);
}
else {
for(unsigned int ix = 0; ix < 3; ++ix)
(*ME())(0, 0, ix) = vertex_->evaluate(scale,vector_[ix],sca,swave_);
}
output = (ME()->contract(rho_)).real()/scale*UnitRemoval::E2;
// colour and identical particle factors
output *= colourFactor(inpart.dataPtr(),decay[0]->dataPtr(),
decay[1]->dataPtr());
// return the answer
return output;
}
Energy SSVDecayer:: partialWidth(PMPair inpart, PMPair outa,
PMPair outb) const {
if( inpart.second < outa.second + outb.second ) return ZERO;
if(perturbativeVertex_) {
double mu1sq(sqr(outa.second/inpart.second)),
mu2sq(sqr(outb.second/inpart.second));
tcPDPtr in = inpart.first->CC() ? tcPDPtr(inpart.first->CC()) : inpart.first;
if(outa.first->iSpin() == PDT::Spin0) {
perturbativeVertex_->setCoupling(sqr(inpart.second), outb.first, outa.first,in);
}
else {
swap(mu1sq,mu2sq);
perturbativeVertex_->setCoupling(sqr(inpart.second), outa.first, outb.first,in);
}
double me2(0.);
if(mu2sq == 0.)
me2 = -2.*mu1sq - 2.;
else
me2 = ( sqr(mu2sq - mu1sq) - 2.*(mu2sq + mu1sq) + 1. )/mu2sq;
Energy pcm = Kinematics::pstarTwoBodyDecay(inpart.second, outa.second,
outb.second);
Energy output = pcm*me2*norm(perturbativeVertex_->norm())/8./Constants::pi;
// colour factor
output *= colourFactor(inpart.first,outa.first,outb.first);
// return the answer
return output;
}
else {
return GeneralTwoBodyDecayer::partialWidth(inpart,outa,outb);
}
}
double SSVDecayer::threeBodyME(const int , const Particle & inpart,
const ParticleVector & decay,
ShowerInteraction inter, MEOption meopt) {
int iscal (0), ivect (1), iglu (2);
// get location of outgoing scalar/vector
if(decay[1]->dataPtr()->iSpin()==PDT::Spin0) swap(iscal,ivect);
// no emissions from massive vectors
if (outgoingVertexV_[inter] && decay[ivect]->dataPtr()->mass()!=ZERO)
throw Exception()
<< "No dipoles available for massive vectors in SSVDecayer::threeBodyME"
<< Exception::runerror;
if(meopt==Initialize) {
// create scalar wavefunction for decaying particle
ScalarWaveFunction::calculateWaveFunctions(rho3_,const_ptr_cast<tPPtr>(&inpart),incoming);
swave3_ = ScalarWaveFunction(inpart.momentum(),inpart.dataPtr(),incoming);
}
// setup spin information when needed
if(meopt==Terminate) {
ScalarWaveFunction::
constructSpinInfo(const_ptr_cast<tPPtr>(&inpart),incoming,true);
ScalarWaveFunction::
constructSpinInfo(decay[iscal],outgoing,true);
VectorWaveFunction::
constructSpinInfo(vector3_,decay[ivect],outgoing,true,false);
VectorWaveFunction::
constructSpinInfo(gluon_, decay[iglu ],outgoing,true,false);
return 0.;
}
// calculate colour factors and number of colour flows
unsigned int nflow;
vector<DVector> cfactors = getColourFactors(inpart, decay, nflow);
if(nflow==2) cfactors[0][1]=cfactors[1][0];
vector<GeneralDecayMEPtr> ME(nflow,new_ptr(GeneralDecayMatrixElement(PDT::Spin0, PDT::Spin0,
PDT::Spin1, PDT::Spin1)));
// create wavefunctions
ScalarWaveFunction scal_(decay[iscal]->momentum(), decay[iscal]->dataPtr(),outgoing);
VectorWaveFunction::calculateWaveFunctions(vector3_,decay[ivect],outgoing,false);
VectorWaveFunction::calculateWaveFunctions(gluon_, decay[iglu ],outgoing,true );
// // gauge invariance test
// gluon_.clear();
// for(unsigned int ix=0;ix<3;++ix) {
// if(ix==1) gluon_.push_back(VectorWaveFunction());
// else {
// gluon_.push_back(VectorWaveFunction(decay[iglu ]->momentum(),
// decay[iglu ]->dataPtr(),10,
// outgoing));
// }
// }
if (! ((incomingVertex_[inter] && (outgoingVertexS_[inter] || outgoingVertexV_[inter])) ||
(outgoingVertexS_[inter] && outgoingVertexV_[inter])))
throw Exception()
<< "Invalid vertices for QCD radiation in SSV decay in SSVDecayer::threeBodyME"
<< Exception::runerror;
// sort out colour flows
int S(1), V(2);
if (decay[iscal]->dataPtr()->iColour()==PDT::Colour3bar &&
decay[ivect]->dataPtr()->iColour()==PDT::Colour8)
swap(S,V);
else if (decay[ivect]->dataPtr()->iColour()==PDT::Colour3 &&
decay[iscal]->dataPtr()->iColour()==PDT::Colour8)
swap(S,V);
Energy2 scale(sqr(inpart.mass()));
const GeneralTwoBodyDecayer::CFlow & colourFlow
= colourFlows(inpart, decay);
for(unsigned int iv = 0; iv < 3; ++iv) {
for(unsigned int ig = 0; ig < 2; ++ig) {
// radiation from the incoming scalar
if(inpart.dataPtr()->coloured()) {
assert(incomingVertex_[inter]);
ScalarWaveFunction scalarInter =
incomingVertex_[inter]->evaluate(scale,3,inpart.dataPtr(),
gluon_[2*ig],swave3_,inpart.mass());
if (swave3_.particle()->PDGName()!=scalarInter.particle()->PDGName())
throw Exception()
<< swave3_ .particle()->PDGName() << " was changed to "
<< scalarInter.particle()->PDGName() << " in SSVDecayer::threeBodyME"
<< Exception::runerror;
double gs = incomingVertex_[inter]->strongCoupling(scale);
double sign = 1.;//inpart.dataPtr()->id()>0 ? 1:-1;
Complex diag = sign * vertex_->evaluate(scale,vector3_[iv],scal_,scalarInter)/gs;
for(unsigned int ix=0;ix<colourFlow[0].size();++ix) {
(*ME[colourFlow[0][ix].first])(0, 0, iv, ig) +=
colourFlow[0][ix].second*diag;
}
}
// radiation from the outgoing scalar
if(decay[iscal]->dataPtr()->coloured()) {
assert(outgoingVertexS_[inter]);
// ensure you get correct outgoing particle from first vertex
tcPDPtr off = decay[iscal]->dataPtr();
if(off->CC()) off = off->CC();
ScalarWaveFunction scalarInter =
outgoingVertexS_[inter]->evaluate(scale,3,off,gluon_[2*ig],scal_,decay[iscal]->mass());
if (scal_.particle()->PDGName()!=scalarInter.particle()->PDGName())
throw Exception()
<< scal_ .particle()->PDGName() << " was changed to "
<< scalarInter.particle()->PDGName() << " in SSVDecayer::threeBodyME"
<< Exception::runerror;
double gs = outgoingVertexS_[inter]->strongCoupling(scale);
double sign = 1.;//decay[iscal]->dataPtr()->id()>0 ? -1:1;
Complex diag = sign*vertex_->evaluate(scale,vector3_[iv],scalarInter,swave3_)/gs;
for(unsigned int ix=0;ix<colourFlow[S].size();++ix) {
(*ME[colourFlow[S][ix].first])(0, 0, iv, ig) +=
colourFlow[S][ix].second*diag;
}
}
// radiation from outgoing vector
if(decay[ivect]->dataPtr()->coloured()) {
assert(outgoingVertexV_[inter]);
// ensure you get correct outgoing particle from first vertex
tcPDPtr off = decay[ivect]->dataPtr();
if(off->CC()) off = off->CC();
VectorWaveFunction vectorInter =
outgoingVertexV_[inter]->evaluate(scale,3,off,gluon_[2*ig],
vector3_[iv],decay[ivect]->mass());
if(vector3_[iv].particle()->PDGName()!=vectorInter.particle()->PDGName())
throw Exception()
<< vector3_[iv].particle()->PDGName() << " was changed to "
<< vectorInter. particle()->PDGName() << " in SSVDecayer::threeBodyME"
<< Exception::runerror;
double sign = 1.;//decay[iscal]->id()>0 ? -1:1;
double gs = outgoingVertexV_[inter]->strongCoupling(scale);
Complex diag = sign*vertex_->evaluate(scale,vectorInter,scal_,swave3_)/gs;
for(unsigned int ix=0;ix<colourFlow[V].size();++ix) {
(*ME[colourFlow[V][ix].first])(0, 0, iv, ig) +=
colourFlow[V][ix].second*diag;
}
}
// radiation from 4 point vertex
if (fourPointVertex_[inter]){
double gs = fourPointVertex_[inter]->strongCoupling(scale);
double sign = decay[iscal]->id()>0 ? -1:-1;
Complex diag = sign*fourPointVertex_[inter]->evaluate(scale, gluon_[2*ig], vector3_[iv],
scal_, swave3_)/gs;
for(unsigned int ix=0;ix<colourFlow[3].size();++ix) {
(*ME[colourFlow[3][ix].first])(0, 0, iv, ig) +=
colourFlow[3][ix].second*diag;
}
}
}
}
// contract matrices
double output=0.;
for(unsigned int ix=0; ix<nflow; ++ix){
for(unsigned int iy=0; iy<nflow; ++iy){
output+=cfactors[ix][iy]*(ME[ix]->contract(*ME[iy],rho3_)).real();
}
}
output*=(4.*Constants::pi);
// return the answer
return output;
}
diff --git a/Decay/Perturbative/SMTopDecayer.cc b/Decay/Perturbative/SMTopDecayer.cc
--- a/Decay/Perturbative/SMTopDecayer.cc
+++ b/Decay/Perturbative/SMTopDecayer.cc
@@ -1,786 +1,790 @@
// -*- C++ -*-
//
// SMTopDecayer.cc is a part of Herwig - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2017 The Herwig Collaboration
//
// Herwig is licenced under version 3 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 SMTopDecayer class.
//
#include "SMTopDecayer.h"
#include "ThePEG/Utilities/DescribeClass.h"
#include "ThePEG/Interface/ClassDocumentation.h"
#include "ThePEG/Interface/ParVector.h"
#include "ThePEG/Interface/Switch.h"
#include "ThePEG/Interface/Reference.h"
#include "ThePEG/Persistency/PersistentOStream.h"
#include "ThePEG/Persistency/PersistentIStream.h"
#include "ThePEG/PDT/DecayMode.h"
#include "Herwig/Decay/DecayVertex.h"
#include "ThePEG/Helicity/WaveFunction/VectorWaveFunction.h"
#include "Herwig/PDT/ThreeBodyAllOn1IntegralCalculator.h"
#include "Herwig/Shower/RealEmissionProcess.h"
#include "Herwig/Shower/Core/Base/ShowerProgenitor.h"
#include "Herwig/Shower/Core/Base/ShowerParticle.h"
#include "Herwig/Shower/Core/Base/Branching.h"
#include "Herwig/Decay/GeneralDecayMatrixElement.h"
using namespace Herwig;
using namespace ThePEG::Helicity;
SMTopDecayer::SMTopDecayer()
: _wquarkwgt(6,0.),_wleptonwgt(3,0.), _xg_sampling(1.5),
_initialenhance(1.), _finalenhance(2.3), _useMEforT2(true) {
_wleptonwgt[0] = 0.302583;
_wleptonwgt[1] = 0.301024;
_wleptonwgt[2] = 0.299548;
_wquarkwgt[0] = 0.851719;
_wquarkwgt[1] = 0.0450162;
_wquarkwgt[2] = 0.0456962;
_wquarkwgt[3] = 0.859839;
_wquarkwgt[4] = 3.9704e-06;
_wquarkwgt[5] = 0.000489657;
generateIntermediates(true);
}
bool SMTopDecayer::accept(tcPDPtr parent, const tPDVector & children) const {
if(abs(parent->id()) != ParticleID::t) return false;
int id0(0),id1(0),id2(0);
for(tPDVector::const_iterator it = children.begin();
it != children.end();++it) {
int id=(**it).id(),absid(abs(id));
if(absid==ParticleID::b&&double(id)/double(parent->id())>0) {
id0=id;
}
else {
switch (absid) {
case ParticleID::nu_e:
case ParticleID::nu_mu:
case ParticleID::nu_tau:
id1 = id;
break;
case ParticleID::eminus:
case ParticleID::muminus:
case ParticleID::tauminus:
id2 = id;
break;
case ParticleID::b:
case ParticleID::d:
case ParticleID::s:
id1 = id;
break;
case ParticleID::u:
case ParticleID::c:
id2=id;
break;
default :
break;
}
}
}
if(id0==0||id1==0||id2==0) return false;
if(double(id1)/double(id2)>0) return false;
return true;
}
ParticleVector SMTopDecayer::decay(const Particle & parent,
const tPDVector & children) const {
int id1(0),id2(0);
for(tPDVector::const_iterator it = children.begin();
it != children.end();++it) {
int id=(**it).id(),absid=abs(id);
if(absid == ParticleID::b && double(id)/double(parent.id())>0) continue;
//leptons
if(absid > 10 && absid%2==0) id1=absid;
if(absid > 10 && absid%2==1) id2=absid;
//quarks
if(absid < 10 && absid%2==0) id2=absid;
if(absid < 10 && absid%2==1) id1=absid;
}
unsigned int imode(0);
if(id2 >=11 && id2<=16) imode = (id1-12)/2;
else imode = id1+1+id2/2;
bool cc = parent.id() == ParticleID::tbar;
ParticleVector out(generate(true,cc,imode,parent));
//arrange colour flow
PPtr pparent=const_ptr_cast<PPtr>(&parent);
out[1]->incomingColour(pparent,out[1]->id()<0);
ParticleVector products = out[0]->children();
if(products[0]->hasColour())
products[0]->colourNeighbour(products[1],true);
else if(products[0]->hasAntiColour())
products[0]->colourNeighbour(products[1],false);
return out;
}
void SMTopDecayer::persistentOutput(PersistentOStream & os) const {
os << FFWVertex_ << FFGVertex_ << FFPVertex_ << WWWVertex_
<< _wquarkwgt << _wleptonwgt << _wplus
<< _initialenhance << _finalenhance << _xg_sampling << _useMEforT2;
}
void SMTopDecayer::persistentInput(PersistentIStream & is, int) {
is >> FFWVertex_ >> FFGVertex_ >> FFPVertex_ >> WWWVertex_
>> _wquarkwgt >> _wleptonwgt >> _wplus
>> _initialenhance >> _finalenhance >> _xg_sampling >> _useMEforT2;
}
// The following static variable is needed for the type
// description system in ThePEG.
DescribeClass<SMTopDecayer,PerturbativeDecayer>
describeHerwigSMTopDecayer("Herwig::SMTopDecayer", "HwPerturbativeDecay.so");
void SMTopDecayer::Init() {
static ClassDocumentation<SMTopDecayer> documentation
("This is the implementation of the SMTopDecayer which "
"decays top quarks into bottom quarks and either leptons "
"or quark-antiquark pairs including the matrix element for top decay",
"The matrix element correction for top decay \\cite{Hamilton:2006ms}.",
"%\\cite{Hamilton:2006ms}\n"
"\\bibitem{Hamilton:2006ms}\n"
" K.~Hamilton and P.~Richardson,\n"
" ``A simulation of QCD radiation in top quark decays,''\n"
" JHEP {\\bf 0702}, 069 (2007)\n"
" [arXiv:hep-ph/0612236].\n"
" %%CITATION = JHEPA,0702,069;%%\n");
static ParVector<SMTopDecayer,double> interfaceQuarkWeights
("QuarkWeights",
"Maximum weights for the hadronic decays",
&SMTopDecayer::_wquarkwgt, 6, 1.0, 0.0, 10.0,
false, false, Interface::limited);
static ParVector<SMTopDecayer,double> interfaceLeptonWeights
("LeptonWeights",
"Maximum weights for the semi-leptonic decays",
&SMTopDecayer::_wleptonwgt, 3, 1.0, 0.0, 10.0,
false, false, Interface::limited);
static Parameter<SMTopDecayer,double> interfaceEnhancementFactor
("InitialEnhancementFactor",
"The enhancement factor for initial-state radiation in the shower to ensure"
" the weight for the matrix element correction is less than one.",
&SMTopDecayer::_initialenhance, 1.0, 1.0, 10000.0,
false, false, Interface::limited);
static Parameter<SMTopDecayer,double> interfaceFinalEnhancementFactor
("FinalEnhancementFactor",
"The enhancement factor for final-state radiation in the shower to ensure"
" the weight for the matrix element correction is less than one",
&SMTopDecayer::_finalenhance, 1.6, 1.0, 1000.0,
false, false, Interface::limited);
static Parameter<SMTopDecayer,double> interfaceSamplingTopHardMEC
("SamplingTopHardMEC",
"The importance sampling power for choosing an initial xg, "
"to sample xg according to xg^-_xg_sampling",
&SMTopDecayer::_xg_sampling, 1.5, 1.2, 2.0,
false, false, Interface::limited);
static Switch<SMTopDecayer,bool> interfaceUseMEForT2
("UseMEForT2",
"Use the matrix element correction, if available to fill the T2"
" region for the decay shower and don't fill using the shower",
&SMTopDecayer::_useMEforT2, true, false, false);
static SwitchOption interfaceUseMEForT2Shower
(interfaceUseMEForT2,
"Shower",
"Use the shower to fill the T2 region",
false);
static SwitchOption interfaceUseMEForT2ME
(interfaceUseMEForT2,
"ME",
"Use the Matrix element to fill the T2 region",
true);
}
double SMTopDecayer::me2(const int, const Particle & inpart,
const ParticleVector & decay,
MEOption meopt) const {
if(!ME())
ME(new_ptr(GeneralDecayMatrixElement(PDT::Spin1Half,PDT::Spin1Half,
PDT::Spin1Half,PDT::Spin1Half)));
// spinors etc for the decaying particle
if(meopt==Initialize) {
// spinors and rho
if(inpart.id()>0)
SpinorWaveFunction ::calculateWaveFunctions(_inHalf,_rho,
const_ptr_cast<tPPtr>(&inpart),
incoming);
else
SpinorBarWaveFunction::calculateWaveFunctions(_inHalfBar,_rho,
const_ptr_cast<tPPtr>(&inpart),
incoming);
}
// setup spin info when needed
if(meopt==Terminate) {
// for the decaying particle
if(inpart.id()>0) {
SpinorWaveFunction::
constructSpinInfo(_inHalf,const_ptr_cast<tPPtr>(&inpart),incoming,true);
SpinorBarWaveFunction::constructSpinInfo(_inHalfBar,decay[0],outgoing,true);
SpinorWaveFunction ::constructSpinInfo(_outHalf ,decay[1],outgoing,true);
SpinorBarWaveFunction::constructSpinInfo(_outHalfBar,decay[2],outgoing,true);
}
else {
SpinorBarWaveFunction::
constructSpinInfo(_inHalfBar,const_ptr_cast<tPPtr>(&inpart),incoming,true);
SpinorWaveFunction::constructSpinInfo(_inHalf,decay[0],outgoing,true);
SpinorBarWaveFunction::constructSpinInfo(_outHalfBar,decay[1],outgoing,true);
SpinorWaveFunction ::constructSpinInfo(_outHalf ,decay[2],outgoing,true);
}
}
if ( ( decay[1]->momentum() + decay[2]->momentum() ).m()
< decay[1]->data().constituentMass() + decay[2]->data().constituentMass() )
return 0.0;
// spinors for the decay product
if(inpart.id()>0) {
SpinorBarWaveFunction::calculateWaveFunctions(_inHalfBar ,decay[0],outgoing);
SpinorWaveFunction ::calculateWaveFunctions(_outHalf ,decay[1],outgoing);
SpinorBarWaveFunction::calculateWaveFunctions(_outHalfBar,decay[2],outgoing);
}
else {
SpinorWaveFunction ::calculateWaveFunctions(_inHalf ,decay[0],outgoing);
SpinorBarWaveFunction::calculateWaveFunctions(_outHalfBar,decay[1],outgoing);
SpinorWaveFunction ::calculateWaveFunctions(_outHalf ,decay[2],outgoing);
}
Energy2 scale(sqr(inpart.mass()));
if(inpart.id() == ParticleID::t) {
//Define intermediate vector wave-function for Wplus
tcPDPtr Wplus(getParticleData(ParticleID::Wplus));
VectorWaveFunction inter;
unsigned int thel,bhel,fhel,afhel;
for(thel = 0;thel<2;++thel){
for(bhel = 0;bhel<2;++bhel){
inter = FFWVertex_->evaluate(scale,1,Wplus,_inHalf[thel],
_inHalfBar[bhel]);
for(afhel=0;afhel<2;++afhel){
for(fhel=0;fhel<2;++fhel){
(*ME())(thel,bhel,afhel,fhel) =
FFWVertex_->evaluate(scale,_outHalf[afhel],
_outHalfBar[fhel],inter);
}
}
}
}
}
else if(inpart.id() == ParticleID::tbar) {
VectorWaveFunction inter;
tcPDPtr Wminus(getParticleData(ParticleID::Wminus));
unsigned int tbhel,bbhel,afhel,fhel;
for(tbhel = 0;tbhel<2;++tbhel){
for(bbhel = 0;bbhel<2;++bbhel){
inter = FFWVertex_->
evaluate(scale,1,Wminus,_inHalf[bbhel],_inHalfBar[tbhel]);
for(afhel=0;afhel<2;++afhel){
for(fhel=0;fhel<2;++fhel){
(*ME())(tbhel,bbhel,fhel,afhel) =
FFWVertex_->evaluate(scale,_outHalf[afhel],
_outHalfBar[fhel],inter);
}
}
}
}
}
double output = (ME()->contract(_rho)).real();
if(abs(decay[1]->id())<=6) output *=3.;
return output;
}
void SMTopDecayer::doinit() {
PerturbativeDecayer::doinit();
//get vertices from SM object
tcHwSMPtr hwsm = dynamic_ptr_cast<tcHwSMPtr>(standardModel());
if(!hwsm) throw InitException() << "Must have Herwig::StandardModel in "
<< "SMTopDecayer::doinit()";
FFWVertex_ = hwsm->vertexFFW();
FFGVertex_ = hwsm->vertexFFG();
FFPVertex_ = hwsm->vertexFFP();
WWWVertex_ = hwsm->vertexWWW();
//initialise
FFWVertex_->init();
FFGVertex_->init();
FFPVertex_->init();
WWWVertex_->init();
//set up decay modes
_wplus = getParticleData(ParticleID::Wplus);
DecayPhaseSpaceModePtr mode;
DecayPhaseSpaceChannelPtr Wchannel;
tPDVector extpart(4);
vector<double> wgt(1,1.0);
extpart[0] = getParticleData(ParticleID::t);
extpart[1] = getParticleData(ParticleID::b);
//lepton modes
for(int i=11; i<17;i+=2) {
extpart[2] = getParticleData(-i);
extpart[3] = getParticleData(i+1);
mode = new_ptr(DecayPhaseSpaceMode(extpart,this));
Wchannel = new_ptr(DecayPhaseSpaceChannel(mode));
Wchannel->addIntermediate(extpart[0],0,0.0,-1,1);
Wchannel->addIntermediate(_wplus,0,0.0,2,3);
Wchannel->init();
mode->addChannel(Wchannel);
addMode(mode,_wleptonwgt[(i-11)/2],wgt);
}
//quark modes
unsigned int iz=0;
for(int ix=1;ix<6;ix+=2) {
for(int iy=2;iy<6;iy+=2) {
// check that the combination of particles is allowed
if(FFWVertex_->allowed(-ix,iy,ParticleID::Wminus)) {
extpart[2] = getParticleData(-ix);
extpart[3] = getParticleData( iy);
mode = new_ptr(DecayPhaseSpaceMode(extpart,this));
Wchannel = new_ptr(DecayPhaseSpaceChannel(mode));
Wchannel->addIntermediate(extpart[0],0,0.0,-1,1);
Wchannel->addIntermediate(_wplus,0,0.0,2,3);
Wchannel->init();
mode->addChannel(Wchannel);
addMode(mode,_wquarkwgt[iz],wgt);
++iz;
}
else {
throw InitException() << "SMTopDecayer::doinit() the W vertex"
<< "cannot handle all the quark modes"
<< Exception::abortnow;
}
}
}
}
void SMTopDecayer::dataBaseOutput(ofstream & os,bool header) const {
if(header) os << "update decayers set parameters=\"";
// parameters for the PerturbativeDecayer base class
for(unsigned int ix=0;ix<_wquarkwgt.size();++ix) {
os << "newdef " << name() << ":QuarkWeights " << ix << " "
<< _wquarkwgt[ix] << "\n";
}
for(unsigned int ix=0;ix<_wleptonwgt.size();++ix) {
os << "newdef " << name() << ":LeptonWeights " << ix << " "
<< _wleptonwgt[ix] << "\n";
}
PerturbativeDecayer::dataBaseOutput(os,false);
if(header) os << "\n\" where BINARY ThePEGName=\"" << fullName() << "\";" << endl;
}
void SMTopDecayer::doinitrun() {
PerturbativeDecayer::doinitrun();
if(initialize()) {
for(unsigned int ix=0;ix<numberModes();++ix) {
if(ix<3) _wleptonwgt[ix ] = mode(ix)->maxWeight();
else _wquarkwgt [ix-3] = mode(ix)->maxWeight();
}
}
}
WidthCalculatorBasePtr SMTopDecayer::threeBodyMEIntegrator(const DecayMode & dm) const {
// identify W decay products
int sign = dm.parent()->id() > 0 ? 1 : -1;
int iferm(0),ianti(0);
for(ParticleMSet::const_iterator pit=dm.products().begin();
pit!=dm.products().end();++pit) {
int id = (**pit).id();
if(id*sign != ParticleID::b) {
if (id*sign > 0 ) iferm = id*sign;
else ianti = id*sign;
}
}
assert(iferm!=0&&ianti!=0);
// work out which mode we are doing
int imode(-1);
for(unsigned int ix=0;ix<numberModes();++ix) {
if(mode(ix)->externalParticles(2)->id() == ianti &&
mode(ix)->externalParticles(3)->id() == iferm ) {
imode = ix;
break;
}
}
assert(imode>=0);
// get the masses we need
Energy m[3] = {mode(imode)->externalParticles(1)->mass(),
mode(imode)->externalParticles(3)->mass(),
mode(imode)->externalParticles(2)->mass()};
return
new_ptr(ThreeBodyAllOn1IntegralCalculator<SMTopDecayer>
(3,_wplus->mass(),_wplus->width(),0.0,*this,imode,m[0],m[1],m[2]));
}
InvEnergy SMTopDecayer::threeBodydGammads(const int imode, const Energy2 mt2,
const Energy2 mffb2, const Energy mb,
const Energy mf, const Energy mfb) const {
Energy mffb(sqrt(mffb2));
Energy mw(_wplus->mass());
Energy2 mw2(sqr(mw)),gw2(sqr(_wplus->width()));
Energy mt(sqrt(mt2));
Energy Eb = 0.5*(mt2-mffb2-sqr(mb))/mffb;
Energy Ef = 0.5*(mffb2-sqr(mfb)+sqr(mf))/mffb;
Energy Ebm = sqrt(sqr(Eb)-sqr(mb));
Energy Efm = sqrt(sqr(Ef)-sqr(mf));
Energy2 upp = sqr(Eb+Ef)-sqr(Ebm-Efm);
Energy2 low = sqr(Eb+Ef)-sqr(Ebm+Efm);
InvEnergy width=(dGammaIntegrand(mffb2,upp,mt,mb,mf,mfb,mw)-
dGammaIntegrand(mffb2,low,mt,mb,mf,mfb,mw))
/32./mt2/mt/8/pow(Constants::pi,3)/(sqr(mffb2-mw2)+mw2*gw2);
// couplings
width *= 0.25*sqr(4.*Constants::pi*generator()->standardModel()->alphaEM(mt2)/
generator()->standardModel()->sin2ThetaW());
width *= generator()->standardModel()->CKM(*mode(imode)->externalParticles(0),
*mode(imode)->externalParticles(1));
if(abs(mode(imode)->externalParticles(2)->id())<=6) {
width *=3.;
if(abs(mode(imode)->externalParticles(2)->id())%2==0)
width *=generator()->standardModel()->CKM(*mode(imode)->externalParticles(2),
*mode(imode)->externalParticles(3));
else
width *=generator()->standardModel()->CKM(*mode(imode)->externalParticles(3),
*mode(imode)->externalParticles(2));
}
// final spin average
assert(!std::isnan(double(width*MeV)));
return 0.5*width;
}
Energy6 SMTopDecayer::dGammaIntegrand(Energy2 mffb2, Energy2 mbf2, Energy mt,
Energy mb, Energy mf, Energy mfb, Energy mw) const {
Energy2 mt2(sqr(mt)) ,mb2(sqr(mb)) ,mf2(sqr(mf )),mfb2(sqr(mfb )),mw2(sqr(mw ));
Energy4 mt4(sqr(mt2)),mb4(sqr(mb2)),mf4(sqr(mf2)),mfb4(sqr(mfb2)),mw4(sqr(mw2));
return -mbf2 * ( + 6 * mb2 * mf2 * mfb2 * mffb2 + 6 * mb2 * mt2 * mfb2 * mffb2
+ 6 * mb2 * mt2 * mf2 * mffb2 + 12 * mb2 * mt2 * mf2 * mfb2
- 3 * mb2 * mfb4 * mffb2 + 3 * mb2 * mf2 * mffb2 * mffb2
- 3 * mb2 * mf4 * mffb2 - 6 * mb2 * mt2 * mfb4
- 6 * mb2 * mt2 * mf4 - 3 * mb4 * mfb2 * mffb2
- 3 * mb4 * mf2 * mffb2 - 6 * mb4 * mf2 * mfb2
+ 3 * mt4 * mf4 + 3 * mb4 * mfb4
+ 3 * mb4 * mf4 + 3 * mt4 * mfb4
+ 3 * mb2 * mfb2 * mffb2 * mffb2 + 3 * mt2 * mfb2 * mffb2 * mffb2
- 3 * mt2 * mfb4 * mffb2 + 3 * mt2 * mf2 * mffb2 * mffb2
- 3 * mt2 * mf4 * mffb2 - 3 * mt4 * mfb2 * mffb2
- 3 * mt4 * mf2 * mffb2 - 6 * mt4 * mf2 * mfb2
+ 6 * mt2 * mf2 * mfb2 * mffb2 + 12 * mt2 * mf2 * mw4
+ 12 * mb2 * mfb2 * mw4 + 12 * mb2 * mt2 * mw4
+ 6 * mw2 * mt2 * mfb2 * mbf2 - 12 * mw2 * mt2 * mf2 * mffb2
- 6 * mw2 * mt2 * mf2 * mbf2 - 12 * mw2 * mt2 * mf2 * mfb2
- 12 * mw2 * mb2 * mfb2 * mffb2 - 6 * mw2 * mb2 * mfb2 * mbf2
+ 6 * mw2 * mb2 * mf2 * mbf2 - 12 * mw2 * mb2 * mf2 * mfb2
- 12 * mw2 * mb2 * mt2 * mfb2 - 12 * mw2 * mb2 * mt2 * mf2
+ 12 * mf2 * mfb2 * mw4 + 4 * mbf2 * mbf2 * mw4
- 6 * mfb2 * mbf2 * mw4 - 6 * mf2 * mbf2 * mw4
- 6 * mt2 * mbf2 * mw4 - 6 * mb2 * mbf2 * mw4
+ 12 * mw2 * mt2 * mf4 + 12 * mw2 * mt4 * mf2
+ 12 * mw2 * mb2 * mfb4 + 12 * mw2 * mb4 * mfb2) /mw4 / 3.;
}
void SMTopDecayer::initializeMECorrection(RealEmissionProcessPtr born, double & initial,
double & final) {
// check the outgoing particles
PPtr part[2];
for(unsigned int ix=0;ix<born->bornOutgoing().size();++ix) {
part[ix]= born->bornOutgoing()[ix];
}
// check the final-state particles and get the masses
if(abs(part[0]->id())==ParticleID::Wplus&&abs(part[1]->id())==ParticleID::b) {
_ma=part[0]->mass();
_mc=part[1]->mass();
}
else if(abs(part[1]->id())==ParticleID::Wplus&&abs(part[0]->id())==ParticleID::b) {
_ma=part[1]->mass();
_mc=part[0]->mass();
}
else {
return;
}
// set the top mass
_mt=born->bornIncoming()[0]->mass();
// set the gluon mass
_mg=getParticleData(ParticleID::g)->constituentMass();
// set the radiation enhancement factors
initial = _initialenhance;
final = _finalenhance;
// reduced mass parameters
_a=sqr(_ma/_mt);
_g=sqr(_mg/_mt);
_c=sqr(_mc/_mt);
double lambda = sqrt(1.+sqr(_a)+sqr(_c)-2.*_a-2.*_c-2.*_a*_c);
_ktb = 0.5*(3.-_a+_c+lambda);
_ktc = 0.5*(1.-_a+3.*_c+lambda);
useMe();
}
bool SMTopDecayer::softMatrixElementVeto(ShowerProgenitorPtr initial,
ShowerParticlePtr parent,Branching br) {
// check if we need to apply the full correction
long id[2]={abs(initial->progenitor()->id()),abs(parent->id())};
// the initial-state correction
if(id[0]==ParticleID::t&&id[1]==ParticleID::t) {
Energy pt=br.kinematics->pT();
// check if hardest so far
// if not just need to remove effect of enhancement
bool veto(false);
// if not hardest so far
if(pt<initial->highestpT())
veto=!UseRandom::rndbool(1./_initialenhance);
// if hardest so far do calculation
else {
// values of kappa and z
double z(br.kinematics->z()),kappa(sqr(br.kinematics->scale()/_mt));
// parameters for the translation
double w(1.-(1.-z)*(kappa-1.)),u(1.+_a-_c-(1.-z)*kappa),v(sqr(u)-4.*_a*w*z);
// veto if outside phase space
if(v<0.)
veto=true;
// otherwise calculate the weight
else {
v = sqrt(v);
double xa((0.5*(u+v)/w+0.5*(u-v)/z)),xg((1.-z)*kappa);
double f(me(xa,xg)),
J(0.5*(u+v)/sqr(w)-0.5*(u-v)/sqr(z)+_a*sqr(w-z)/(v*w*z));
double wgt(f*J*2./kappa/(1.+sqr(z)-2.*z/kappa)/_initialenhance);
// This next `if' prevents the hardest emission from the
// top shower ever entering the so-called T2 region of the
// phase space if that region is to be populated by the hard MEC.
if(_useMEforT2&&xg>xgbcut(_ktb)) wgt = 0.;
if(wgt>1.) {
generator()->log() << "Violation of maximum for initial-state "
<< " soft veto in "
<< "SMTopDecayer::softMatrixElementVeto"
<< "xg = " << xg << " xa = " << xa
<< "weight = " << wgt << "\n";
wgt=1.;
}
// compute veto from weight
veto = !UseRandom::rndbool(wgt);
}
// if not vetoed reset max
if(!veto) initial->highestpT(pt);
}
// if vetoing reset the scale
if(veto) parent->vetoEmission(br.type,br.kinematics->scale());
// return the veto
return veto;
}
// final-state correction
else if(id[0]==ParticleID::b&&id[1]==ParticleID::b) {
Energy pt=br.kinematics->pT();
// check if hardest so far
// if not just need to remove effect of enhancement
bool veto(false);
// if not hardest so far
if(pt<initial->highestpT()) return !UseRandom::rndbool(1./_finalenhance);
// if hardest so far do calculation
// values of kappa and z
double z(br.kinematics->z()),kappa(sqr(br.kinematics->scale()/_mt));
// momentum fractions
double xa(1.+_a-_c-z*(1.-z)*kappa),r(0.5*(1.+_c/(1.+_a-xa))),root(sqr(xa)-4.*_a);
if(root<0.) {
generator()->log() << "Imaginary root for final-state veto in "
<< "SMTopDecayer::softMatrixElementVeto"
<< "\nz = " << z << "\nkappa = " << kappa
<< "\nxa = " << xa
<< "\nroot^2= " << root;
parent->vetoEmission(br.type,br.kinematics->scale());
return true;
}
root=sqrt(root);
double xg((2.-xa)*(1.-r)-(z-r)*root);
// xfact (below) is supposed to equal xg/(1-z).
double xfact(z*kappa/2./(z*(1.-z)*kappa+_c)*(2.-xa-root)+root);
// calculate the full result
double f(me(xa,xg));
// jacobian
double J(z*root);
double wgt(f*J*2.*kappa/(1.+sqr(z)-2.*_c/kappa/z)/sqr(xfact)/_finalenhance);
if(wgt>1.) {
generator()->log() << "Violation of maximum for final-state soft veto in "
<< "SMTopDecayer::softMatrixElementVeto"
<< "xg = " << xg << " xa = " << xa
<< "weight = " << wgt << "\n";
wgt=1.;
}
// compute veto from weight
veto = !UseRandom::rndbool(wgt);
// if vetoing reset the scale
if(veto) parent->vetoEmission(br.type,br.kinematics->scale());
// return the veto
return veto;
}
// otherwise don't veto
else return !UseRandom::rndbool(1./_finalenhance);
}
double SMTopDecayer::me(double xw,double xg) {
double prop(1.+_a-_c-xw),xg2(sqr(xg));
double lambda=sqrt(1.+_a*_a+_c*_c-2.*_a-2.*_c-2.*_a*_c);
double denom=(1.-2*_a*_a+_a+_c*_a+_c*_c-2.*_c);
double wgt=-_c*xg2/prop+(1.-_a+_c)*xg-(prop*(1 - xg)+xg2)
+(0.5*(1.+2.*_a+_c)*sqr(prop-xg)*xg+2.*_a*prop*xg2)/denom;
return wgt/(lambda*prop);
}
// xgbcut is the point along the xg axis where the upper bound on the
// top quark (i.e. b) emission phase space goes back on itself in the
// xa vs xg plane i.e. roughly mid-way along the xg axis in
// the xa vs xg Dalitz plot.
double SMTopDecayer::xgbcut(double kt) {
double lambda2 = 1.+_a*_a+_c*_c-2.*_a-2.*_c-2.*_a*_c;
double num1 = kt*kt*(1.-_a-_c);
double num2 = 2.*kt*sqrt(_a*(kt*kt*_c+lambda2*(kt-1.)));
return (num1-num2)/(kt*kt-4.*_a*(kt-1.));
}
double SMTopDecayer::loME(const Particle & inpart, const ParticleVector & decay) {
// spinors
vector<SpinorWaveFunction > swave;
vector<SpinorBarWaveFunction> awave;
vector<VectorWaveFunction> vwave;
+ tPPtr Wboson = abs(decay[0]->id())==ParticleID::Wplus ? decay[0] : decay[1];
+ tPPtr bquark = abs(decay[0]->id())==ParticleID::Wplus ? decay[1] : decay[0];
// spinors
if(inpart.id()>0) {
SpinorWaveFunction ::calculateWaveFunctions(swave,const_ptr_cast<tPPtr>(&inpart),
incoming);
- SpinorBarWaveFunction::calculateWaveFunctions(awave,decay[0],outgoing);
+ SpinorBarWaveFunction::calculateWaveFunctions(awave,bquark,outgoing);
}
else {
SpinorBarWaveFunction::calculateWaveFunctions(awave,const_ptr_cast<tPPtr>(&inpart),
incoming);
- SpinorWaveFunction ::calculateWaveFunctions(swave,decay[0],outgoing);
+ SpinorWaveFunction ::calculateWaveFunctions(swave,bquark,outgoing);
}
// polarization vectors
- VectorWaveFunction::calculateWaveFunctions(vwave,decay[1],outgoing,false);
+ VectorWaveFunction::calculateWaveFunctions(vwave,Wboson,outgoing,false);
Energy2 scale(sqr(inpart.mass()));
double me=0.;
if(inpart.id() == ParticleID::t) {
for(unsigned int thel = 0; thel < 2; ++thel) {
for(unsigned int bhel = 0; bhel < 2; ++bhel) {
for(unsigned int whel = 0; whel < 3; ++whel) {
Complex diag = FFWVertex_->evaluate(scale,swave[thel],awave[bhel],vwave[whel]);
me += norm(diag);
}
}
}
}
else if(inpart.id() == ParticleID::tbar) {
for(unsigned int thel = 0; thel < 2; ++thel) {
for(unsigned int bhel = 0; bhel < 2; ++bhel){
for(unsigned int whel = 0; whel < 3; ++whel) {
Complex diag = FFWVertex_->evaluate(scale,swave[bhel],awave[thel],vwave[whel]);
me += norm(diag);
}
}
}
}
return me;
}
double SMTopDecayer::realME(const Particle & inpart, const ParticleVector & decay,
ShowerInteraction inter) {
// vertex for emission from fermions
AbstractFFVVertexPtr vertex = inter==ShowerInteraction::QCD ? FFGVertex_ : FFPVertex_;
// spinors
vector<SpinorWaveFunction > swave;
vector<SpinorBarWaveFunction> awave;
vector<VectorWaveFunction> vwave,gwave;
+ tPPtr Wboson = abs(decay[0]->id())==ParticleID::Wplus ? decay[0] : decay[1];
+ tPPtr bquark = abs(decay[0]->id())==ParticleID::Wplus ? decay[1] : decay[0];
// spinors
if(inpart.id()>0) {
SpinorWaveFunction ::calculateWaveFunctions(swave,const_ptr_cast<tPPtr>(&inpart),
incoming);
- SpinorBarWaveFunction::calculateWaveFunctions(awave,decay[0],outgoing);
+ SpinorBarWaveFunction::calculateWaveFunctions(awave,bquark,outgoing);
}
else {
SpinorBarWaveFunction::calculateWaveFunctions(awave,const_ptr_cast<tPPtr>(&inpart),
incoming);
- SpinorWaveFunction ::calculateWaveFunctions(swave,decay[0],outgoing);
+ SpinorWaveFunction ::calculateWaveFunctions(swave,bquark,outgoing);
}
// polarization vectors
- VectorWaveFunction::calculateWaveFunctions(vwave,decay[1],outgoing,false);
+ VectorWaveFunction::calculateWaveFunctions(vwave,Wboson,outgoing,false);
VectorWaveFunction::calculateWaveFunctions(gwave,decay[2],outgoing,true );
Energy2 scale(sqr(inpart.mass()));
double me=0.;
vector<Complex> diag(3,0.);
if(inpart.id() == ParticleID::t) {
for(unsigned int thel = 0; thel < 2; ++thel) {
for(unsigned int bhel = 0; bhel < 2; ++bhel) {
for(unsigned int whel = 0; whel < 3; ++whel) {
for(unsigned int ghel =0; ghel <3; ghel+=2) {
// emission from top
SpinorWaveFunction interF = vertex->evaluate(scale,3,inpart.dataPtr(),swave[thel],gwave[ghel]);
diag[0] = FFWVertex_->evaluate(scale,interF,awave[bhel],vwave[whel]);
// emission from bottom
- SpinorBarWaveFunction interB = vertex->evaluate(scale,3,decay[0]->dataPtr(),awave[bhel],gwave[ghel]);
+ SpinorBarWaveFunction interB = vertex->evaluate(scale,3,bquark->dataPtr(),awave[bhel],gwave[ghel]);
diag[1] = FFWVertex_->evaluate(scale,swave[thel],interB,vwave[whel]);
// emission from W
if(inter==ShowerInteraction::QED) {
- VectorWaveFunction interV = WWWVertex_->evaluate(scale,3,decay[1]->dataPtr()->CC(),vwave[whel],gwave[ghel]);
+ VectorWaveFunction interV = WWWVertex_->evaluate(scale,3,Wboson->dataPtr()->CC(),vwave[whel],gwave[ghel]);
diag[1] = FFWVertex_->evaluate(scale,swave[thel],awave[bhel],interV);
}
Complex sum = std::accumulate(diag.begin(),diag.end(),Complex(0.));
me += norm(sum);
}
}
}
}
}
else if(inpart.id() == ParticleID::tbar) {
for(unsigned int thel = 0; thel < 2; ++thel) {
for(unsigned int bhel = 0; bhel < 2; ++bhel){
for(unsigned int whel = 0; whel < 3; ++whel) {
for(unsigned int ghel =0; ghel <3; ghel+=2) {
// emission from top
SpinorBarWaveFunction interB = vertex->evaluate(scale,3,inpart.dataPtr(),awave[thel],gwave[ghel]);
diag[1] = FFWVertex_->evaluate(scale,swave[bhel],interB,vwave[whel]);
// emission from bottom
- SpinorWaveFunction interF = vertex->evaluate(scale,3,decay[0]->dataPtr(),swave[bhel],gwave[ghel]);
+ SpinorWaveFunction interF = vertex->evaluate(scale,3,bquark->dataPtr(),swave[bhel],gwave[ghel]);
diag[0] = FFWVertex_->evaluate(scale,interF,awave[thel],vwave[whel]);
// emission from W
if(inter==ShowerInteraction::QED) {
- VectorWaveFunction interV = WWWVertex_->evaluate(scale,3,decay[1]->dataPtr()->CC(),vwave[whel],gwave[ghel]);
+ VectorWaveFunction interV = WWWVertex_->evaluate(scale,3,Wboson->dataPtr()->CC(),vwave[whel],gwave[ghel]);
diag[1] = FFWVertex_->evaluate(scale,swave[bhel],awave[thel],interV);
}
Complex sum = std::accumulate(diag.begin(),diag.end(),Complex(0.));
me += norm(sum);
}
}
}
}
}
// divide out the coupling
me /= norm(vertex->norm());
// return the total
return me;
}
double SMTopDecayer::matrixElementRatio(const Particle & inpart,
const ParticleVector & decay2,
const ParticleVector & decay3,
MEOption ,
ShowerInteraction inter) {
double Nc = standardModel()->Nc();
double Cf = (sqr(Nc) - 1.) / (2.*Nc);
// if(inter==ShowerInteraction::QED) return 0.;
// double f = (1. + sqr(e2()) - 2.*sqr(s2()) + s2() + s2()*e2() - 2.*e2());
//
//
// double B = f/s2();
// Energy2 PbPg = decay3[0]->momentum()*decay3[2]->momentum();
// Energy2 PtPg = inpart.momentum()*decay3[2]->momentum();
// Energy2 PtPb = inpart.momentum()*decay3[0]->momentum();
// double R = Cf *((-4.*sqr(mb())*f/s2()) * ((sqr(mb())*e2()/sqr(PbPg)) +
// (sqr(mb())/sqr(PtPg)) - 2.*(PtPb/(PtPg*PbPg))) +
// (16. + 8./s2() + 8.*e2()/s2()) * ((PtPg/PbPg) + (PbPg/PtPg)) -
// (16./s2()) * (1. + e2()));
// return R/B*Constants::pi;
double Bnew = loME(inpart,decay2);
double Rnew = realME(inpart,decay3,inter);
double output = Rnew/Bnew*4.*Constants::pi*sqr(inpart.mass())*UnitRemoval::InvE2;
if(inter==ShowerInteraction::QCD) output *= Cf;
return output;
}
diff --git a/Decay/PerturbativeDecayer.cc b/Decay/PerturbativeDecayer.cc
--- a/Decay/PerturbativeDecayer.cc
+++ b/Decay/PerturbativeDecayer.cc
@@ -1,944 +1,957 @@
// -*- C++ -*-
//
// This is the implementation of the non-inlined, non-templated member
// functions of the PerturbativeDecayer class.
//
#include "PerturbativeDecayer.h"
#include "ThePEG/Interface/ClassDocumentation.h"
#include "ThePEG/EventRecord/Particle.h"
#include "ThePEG/Repository/UseRandom.h"
#include "ThePEG/Repository/EventGenerator.h"
#include "ThePEG/Utilities/DescribeClass.h"
#include "ThePEG/Persistency/PersistentOStream.h"
#include "ThePEG/Persistency/PersistentIStream.h"
#include "ThePEG/Interface/Reference.h"
#include "ThePEG/Interface/Parameter.h"
#include "ThePEG/Interface/Switch.h"
#include "ThePEG/Utilities/EnumIO.h"
using namespace Herwig;
void PerturbativeDecayer::persistentOutput(PersistentOStream & os) const {
os << ounit(pTmin_,GeV) << oenum(inter_) << alphaS_ << alphaEM_;
}
void PerturbativeDecayer::persistentInput(PersistentIStream & is, int) {
is >> iunit(pTmin_,GeV) >> ienum(inter_) >> alphaS_ >> alphaEM_;
}
// The following static variable is needed for the type
// description system in ThePEG.
DescribeAbstractClass<PerturbativeDecayer,DecayIntegrator>
describeHerwigPerturbativeDecayer("Herwig::PerturbativeDecayer",
"Herwig.so HwPerturbativeDecay.so");
void PerturbativeDecayer::Init() {
static ClassDocumentation<PerturbativeDecayer> documentation
("The PerturbativeDecayer class is the mase class for perturbative decays in Herwig");
static Parameter<PerturbativeDecayer,Energy> interfacepTmin
("pTmin",
"Minimum transverse momentum from gluon radiation",
&PerturbativeDecayer::pTmin_, GeV, 1.0*GeV, 0.0*GeV, 10.0*GeV,
false, false, Interface::limited);
static Switch<PerturbativeDecayer,ShowerInteraction> interfaceInteractions
("Interactions",
"which interactions to include for the hard corrections",
&PerturbativeDecayer::inter_, ShowerInteraction::QCD, false, false);
static SwitchOption interfaceInteractionsQCD
(interfaceInteractions,
"QCD",
"QCD Only",
ShowerInteraction::QCD);
static SwitchOption interfaceInteractionsQED
(interfaceInteractions,
"QED",
"QED only",
ShowerInteraction::QED);
static SwitchOption interfaceInteractionsQCDandQED
(interfaceInteractions,
"QCDandQED",
"Both QCD and QED",
ShowerInteraction::Both);
static Reference<PerturbativeDecayer,ShowerAlpha> interfaceAlphaS
("AlphaS",
"Object for the coupling in the generation of hard QCD radiation",
&PerturbativeDecayer::alphaS_, false, false, true, true, false);
static Reference<PerturbativeDecayer,ShowerAlpha> interfaceAlphaEM
("AlphaEM",
"Object for the coupling in the generation of hard QED radiation",
&PerturbativeDecayer::alphaEM_, false, false, true, true, false);
}
double PerturbativeDecayer::matrixElementRatio(const Particle & ,
const ParticleVector & ,
const ParticleVector & ,
MEOption ,
ShowerInteraction ) {
throw Exception() << "Base class PerturbativeDecayer::matrixElementRatio() "
<< "called, should have an implementation in the inheriting class"
<< Exception::runerror;
return 0.;
}
RealEmissionProcessPtr PerturbativeDecayer::generateHardest(RealEmissionProcessPtr born) {
return getHardEvent(born,false,inter_);
}
RealEmissionProcessPtr PerturbativeDecayer::applyHardMatrixElementCorrection(RealEmissionProcessPtr born) {
return getHardEvent(born,true,ShowerInteraction::QCD);
}
RealEmissionProcessPtr PerturbativeDecayer::getHardEvent(RealEmissionProcessPtr born,
bool inDeadZone,
ShowerInteraction inter) {
// check one incoming
assert(born->bornIncoming().size()==1);
// check exactly two outgoing particles
assert(born->bornOutgoing().size()==2); // search for coloured particles
bool colouredParticles=born->bornIncoming()[0]->dataPtr()->coloured();
bool chargedParticles=born->bornIncoming()[0]->dataPtr()->charged();
for(unsigned int ix=0;ix<born->bornOutgoing().size();++ix) {
if(born->bornOutgoing()[ix]->dataPtr()->coloured())
colouredParticles=true;
if(born->bornOutgoing()[ix]->dataPtr()->charged())
chargedParticles=true;
}
// if no coloured/charged particles return
if ( !colouredParticles && !chargedParticles ) return RealEmissionProcessPtr();
if ( !colouredParticles && inter==ShowerInteraction::QCD ) return RealEmissionProcessPtr();
if ( ! chargedParticles && inter==ShowerInteraction::QED ) return RealEmissionProcessPtr();
// for decay b -> a c
// set progenitors
PPtr cProgenitor = born->bornOutgoing()[0];
PPtr aProgenitor = born->bornOutgoing()[1];
// get the decaying particle
PPtr bProgenitor = born->bornIncoming()[0];
// identify which dipoles are required
vector<DipoleType> dipoles;
if(!identifyDipoles(dipoles,aProgenitor,bProgenitor,cProgenitor,inter)) {
return RealEmissionProcessPtr();
}
Energy trialpT = pTmin_;
LorentzRotation eventFrame;
vector<Lorentz5Momentum> momenta;
vector<Lorentz5Momentum> trialMomenta(4);
PPtr finalEmitter, finalSpectator;
PPtr trialEmitter, trialSpectator;
DipoleType finalType(FFa,ShowerInteraction::QCD);
for (int i=0; i<int(dipoles.size()); ++i) {
// assign emitter and spectator based on current dipole
if (dipoles[i].type==FFc || dipoles[i].type==IFc || dipoles[i].type==IFbc){
trialEmitter = cProgenitor;
trialSpectator = aProgenitor;
}
else if (dipoles[i].type==FFa || dipoles[i].type==IFa || dipoles[i].type==IFba){
trialEmitter = aProgenitor;
trialSpectator = cProgenitor;
}
// find rotation from lab to frame with the spectator along -z
LorentzRotation trialEventFrame(bProgenitor->momentum().findBoostToCM());
Lorentz5Momentum pspectator = (trialEventFrame*trialSpectator->momentum());
trialEventFrame.rotateZ( -pspectator.phi() );
trialEventFrame.rotateY( -pspectator.theta() - Constants::pi );
// invert it
trialEventFrame.invert();
// try to generate an emission
pT_ = pTmin_;
vector<Lorentz5Momentum> trialMomenta
= hardMomenta(bProgenitor, trialEmitter, trialSpectator,
dipoles, i, inDeadZone);
// select dipole which gives highest pT emission
if(pT_>trialpT) {
trialpT = pT_;
momenta = trialMomenta;
eventFrame = trialEventFrame;
finalEmitter = trialEmitter;
finalSpectator = trialSpectator;
finalType = dipoles[i];
if (dipoles[i].type==FFc || dipoles[i].type==FFa ) {
if((momenta[3]+momenta[1]).m2()-momenta[1].m2()>
(momenta[3]+momenta[2]).m2()-momenta[2].m2()) {
swap(finalEmitter,finalSpectator);
swap(momenta[1],momenta[2]);
}
}
}
}
pT_ = trialpT;
// if no emission return
if(momenta.empty()) {
if(inter==ShowerInteraction::Both || inter==ShowerInteraction::QCD)
born->pT()[ShowerInteraction::QCD] = pTmin_;
if(inter==ShowerInteraction::Both || inter==ShowerInteraction::QED)
born->pT()[ShowerInteraction::QED] = pTmin_;
return born;
}
// rotate momenta back to the lab
for(unsigned int ix=0;ix<momenta.size();++ix) {
momenta[ix] *= eventFrame;
}
// set maximum pT for subsequent branchings
if(inter==ShowerInteraction::Both || inter==ShowerInteraction::QCD)
born->pT()[ShowerInteraction::QCD] = pT_;
if(inter==ShowerInteraction::Both || inter==ShowerInteraction::QED)
born->pT()[ShowerInteraction::QED] = pT_;
// get ParticleData objects
tcPDPtr b = bProgenitor ->dataPtr();
tcPDPtr e = finalEmitter ->dataPtr();
tcPDPtr s = finalSpectator->dataPtr();
tcPDPtr boson = getParticleData(finalType.interaction==ShowerInteraction::QCD ?
ParticleID::g : ParticleID::gamma);
// create new ShowerParticles
PPtr emitter = e ->produceParticle(momenta[1]);
PPtr spectator = s ->produceParticle(momenta[2]);
PPtr gauge = boson->produceParticle(momenta[3]);
PPtr incoming = b ->produceParticle(bProgenitor->momentum());
// insert the particles
born->incoming().push_back(incoming);
unsigned int iemit(0),ispect(0);
for(unsigned int ix=0;ix<born->bornOutgoing().size();++ix) {
if(born->bornOutgoing()[ix]==finalEmitter) {
born->outgoing().push_back(emitter);
iemit = born->outgoing().size();
}
else if(born->bornOutgoing()[ix]==finalSpectator) {
born->outgoing().push_back(spectator);
ispect = born->outgoing().size();
}
}
born->outgoing().push_back(gauge);
if(!spectator->dataPtr()->coloured() ||
(finalType.type != FFa && finalType.type!=FFc) ) ispect = 0;
born->emitter(iemit);
born->spectator(ispect);
born->emitted(3);
+ // boost if being use as ME correction
+ if(inDeadZone) {
+ if(finalType.type==IFa || finalType.type==IFba) {
+ LorentzRotation trans(cProgenitor->momentum().findBoostToCM());
+ trans.boost(spectator->momentum().boostVector());
+ born->transformation(trans);
+ }
+ else if(finalType.type==IFc || finalType.type==IFbc) {
+ LorentzRotation trans(bProgenitor->momentum().findBoostToCM());
+ trans.boost(spectator->momentum().boostVector());
+ born->transformation(trans);
+ }
+ }
// set the interaction
born->interaction(finalType.interaction);
// set up colour lines
getColourLines(born);
// return the tree
return born;
}
bool PerturbativeDecayer::identifyDipoles(vector<DipoleType> & dipoles,
PPtr & aProgenitor,
PPtr & bProgenitor,
PPtr & cProgenitor,
ShowerInteraction inter) const {
// identify any QCD dipoles
if(inter==ShowerInteraction::QCD ||
inter==ShowerInteraction::Both) {
PDT::Colour bColour = bProgenitor->dataPtr()->iColour();
PDT::Colour cColour = cProgenitor->dataPtr()->iColour();
PDT::Colour aColour = aProgenitor->dataPtr()->iColour();
// decaying colour singlet
if (bColour==PDT::Colour0 ) {
if ((cColour==PDT::Colour3 && aColour==PDT::Colour3bar) ||
(cColour==PDT::Colour3bar && aColour==PDT::Colour3) ||
(cColour==PDT::Colour8 && aColour==PDT::Colour8)){
dipoles.push_back(DipoleType(FFa,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(FFc,ShowerInteraction::QCD));
}
}
// decaying colour triplet
else if (bColour==PDT::Colour3 ) {
if (cColour==PDT::Colour3 && aColour==PDT::Colour0){
dipoles.push_back(DipoleType(IFbc,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(IFc ,ShowerInteraction::QCD));
}
else if (cColour==PDT::Colour0 && aColour==PDT::Colour3){
dipoles.push_back(DipoleType(IFba,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(IFa ,ShowerInteraction::QCD));
}
else if (cColour==PDT::Colour8 && aColour==PDT::Colour3){
dipoles.push_back(DipoleType(IFbc,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(IFc ,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(FFc ,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(FFa ,ShowerInteraction::QCD));
}
else if (cColour==PDT::Colour3 && aColour==PDT::Colour8){
dipoles.push_back(DipoleType(IFba,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(IFa ,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(FFc ,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(FFa ,ShowerInteraction::QCD));
}
}
// decaying colour anti-triplet
else if (bColour==PDT::Colour3bar) {
if ((cColour==PDT::Colour3bar && aColour==PDT::Colour0)){
dipoles.push_back(DipoleType(IFbc,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(IFc ,ShowerInteraction::QCD));
}
else if ((cColour==PDT::Colour0 && aColour==PDT::Colour3bar)){
dipoles.push_back(DipoleType(IFba,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(IFa ,ShowerInteraction::QCD));
}
else if (cColour==PDT::Colour8 && aColour==PDT::Colour3bar){
dipoles.push_back(DipoleType(IFbc,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(IFc ,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(FFc ,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(FFa ,ShowerInteraction::QCD));
}
else if (cColour==PDT::Colour3bar && aColour==PDT::Colour8){
dipoles.push_back(DipoleType(IFba,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(IFa ,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(FFc ,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(FFa ,ShowerInteraction::QCD));
}
}
// decaying colour octet
else if (bColour==PDT::Colour8){
if ((cColour==PDT::Colour3 && aColour==PDT::Colour3bar) ||
(cColour==PDT::Colour3bar && aColour==PDT::Colour3)){
dipoles.push_back(DipoleType(IFba,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(IFbc,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(IFa,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(IFc,ShowerInteraction::QCD));
}
else if (cColour==PDT::Colour8 && aColour==PDT::Colour0){
dipoles.push_back(DipoleType(IFbc,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(IFc,ShowerInteraction::QCD));
}
else if (cColour==PDT::Colour0 && aColour==PDT::Colour8){
dipoles.push_back(DipoleType(IFba,ShowerInteraction::QCD));
dipoles.push_back(DipoleType(IFa,ShowerInteraction::QCD));
}
}
}
// QED dipoles
if(inter==ShowerInteraction::Both ||
inter==ShowerInteraction::QED) {
const bool & bCharged = bProgenitor->dataPtr()->charged();
const bool & cCharged = cProgenitor->dataPtr()->charged();
const bool & aCharged = aProgenitor->dataPtr()->charged();
// initial-final
if(bCharged && aCharged) {
dipoles.push_back(DipoleType(IFba,ShowerInteraction::QED));
dipoles.push_back(DipoleType(IFa ,ShowerInteraction::QED));
}
if(bCharged && cCharged) {
dipoles.push_back(DipoleType(IFbc,ShowerInteraction::QED));
dipoles.push_back(DipoleType(IFc ,ShowerInteraction::QED));
}
// final-state
if(aCharged && cCharged) {
dipoles.push_back(DipoleType(FFa,ShowerInteraction::QED));
dipoles.push_back(DipoleType(FFc,ShowerInteraction::QED));
}
}
// check colour structure is allowed
return !dipoles.empty();
}
vector<Lorentz5Momentum> PerturbativeDecayer::hardMomenta(PPtr in, PPtr emitter,
PPtr spectator,
const vector<DipoleType> &dipoles,
int i, bool inDeadZone) {
double C = 6.3;
double ymax = 10.;
double ymin = -ymax;
// get masses of the particles
mb_ = in ->momentum().mass();
e_ = emitter ->momentum().mass()/mb_;
s_ = spectator->momentum().mass()/mb_;
e2_ = sqr(e_);
s2_ = sqr(s_);
vector<Lorentz5Momentum> particleMomenta (4);
Energy2 lambda = sqr(mb_)*sqrt(1.+sqr(s2_)+sqr(e2_)-2.*s2_-2.*e2_-2.*s2_*e2_);
// calculate A
double A = (ymax-ymin)*C/Constants::twopi;
if(dipoles[i].interaction==ShowerInteraction::QCD)
A *= alphaS() ->overestimateValue();
else
A *= alphaEM()->overestimateValue();
Energy pTmax = mb_*(sqr(1.-s_)-e2_)/(2.*(1.-s_));
// if no possible branching return
if ( pTmax < pTmin_ ) {
particleMomenta.clear();
return particleMomenta;
}
while (pTmax >= pTmin_) {
// generate pT, y and phi values
Energy pT = pTmax*pow(UseRandom::rnd(),(1./A));
if (pT < pTmin_) {
particleMomenta.clear();
break;
}
double phi = UseRandom::rnd()*Constants::twopi;
double y = ymin+UseRandom::rnd()*(ymax-ymin);
double weight[2] = {0.,0.};
double xs[2], xe[2], xe_z[2], xg;
for (unsigned int j=0; j<2; j++) {
// check if the momenta are physical
if (!calcMomenta(j, pT, y, phi, xg, xs[j], xe[j], xe_z[j], particleMomenta))
continue;
// check if point lies within phase space
if (!psCheck(xg, xs[j]))
continue;
// check if point lies within the dead-zone (if required)
if(inDeadZone) {
if(!inTotalDeadZone(xg,xs[j],dipoles,i)) continue;
}
// decay products for 3 body decay
PPtr inpart = in ->dataPtr()->produceParticle(particleMomenta[0]);
ParticleVector decay3;
decay3.push_back(emitter ->dataPtr()->produceParticle(particleMomenta[1]));
decay3.push_back(spectator->dataPtr()->produceParticle(particleMomenta[2]));
if(dipoles[i].interaction==ShowerInteraction::QCD)
decay3.push_back(getParticleData(ParticleID::g )->produceParticle(particleMomenta[3]));
else
decay3.push_back(getParticleData(ParticleID::gamma)->produceParticle(particleMomenta[3]));
// decay products for 2 body decay
Lorentz5Momentum p1(ZERO,ZERO, lambda/2./mb_,(mb_/2.)*(1.+e2_-s2_),mb_*e_);
Lorentz5Momentum p2(ZERO,ZERO,-lambda/2./mb_,(mb_/2.)*(1.+s2_-e2_),mb_*s_);
ParticleVector decay2;
decay2.push_back(emitter ->dataPtr()->produceParticle(p1));
decay2.push_back(spectator->dataPtr()->produceParticle(p2));
- if (dipoles[i].type==FFc || dipoles[i].type==IFc || dipoles[i].type==IFbc){
+ if (dipoles[i].type==FFa || dipoles[i].type==IFa || dipoles[i].type==IFba) {
swap(decay2[0],decay2[1]);
swap(decay3[0],decay3[1]);
}
// calculate matrix element ratio R/B
double meRatio = matrixElementRatio(*inpart,decay2,decay3,Initialize,dipoles[i].interaction);
// calculate dipole factor
InvEnergy2 dipoleSum = ZERO;
InvEnergy2 numerator = ZERO;
for (int k=0; k<int(dipoles.size()); ++k) {
// skip dipoles which are not of the interaction being considered
if(dipoles[k].interaction!=dipoles[i].interaction) continue;
InvEnergy2 dipole = abs(calculateDipole(dipoles[k],*inpart,decay3));
dipoleSum += dipole;
if (k==i) numerator = dipole;
}
meRatio *= numerator/dipoleSum;
// calculate jacobian
Energy2 denom = (mb_-particleMomenta[3].e())*particleMomenta[2].vect().mag() -
particleMomenta[2].e()*particleMomenta[3].z();
InvEnergy2 J = (particleMomenta[2].vect().mag2())/(lambda*denom);
// calculate weight
weight[j] = meRatio*fabs(sqr(pT)*J)/C/Constants::twopi;
if(dipoles[i].interaction==ShowerInteraction::QCD)
weight[j] *= alphaS() ->ratio(pT*pT);
else
weight[j] *= alphaEM()->ratio(pT*pT);
}
// accept point if weight > R
if (weight[0] + weight[1] > UseRandom::rnd()) {
if (weight[0] > (weight[0] + weight[1])*UseRandom::rnd()) {
particleMomenta[1].setE( (mb_/2.)*xe [0]);
particleMomenta[1].setZ( (mb_/2.)*xe_z[0]);
particleMomenta[2].setE( (mb_/2.)*xs [0]);
particleMomenta[2].setZ(-(mb_/2.)*sqrt(sqr(xs[0])-4.*s2_));
}
else {
particleMomenta[1].setE( (mb_/2.)*xe [1]);
particleMomenta[1].setZ( (mb_/2.)*xe_z[1]);
particleMomenta[2].setE( (mb_/2.)*xs [1]);
particleMomenta[2].setZ(-(mb_/2.)*sqrt(sqr(xs[1])-4.*s2_));
}
pT_ = pT;
break;
}
// if there's no branching lower the pT
pTmax = pT;
}
return particleMomenta;
}
bool PerturbativeDecayer::calcMomenta(int j, Energy pT, double y, double phi,
double& xg, double& xs, double& xe, double& xe_z,
vector<Lorentz5Momentum>& particleMomenta){
// calculate xg
xg = 2.*pT*cosh(y) / mb_;
if (xg>(1. - sqr(e_ + s_)) || xg<0.) return false;
// calculate the two values of xs
double xT = 2.*pT / mb_;
double A = 4.-4.*xg+sqr(xT);
double B = 4.*(3.*xg-2.+2.*e2_-2.*s2_-sqr(xg)-xg*e2_+xg*s2_);
double L = 1.+sqr(s2_)+sqr(e2_)-2.*s2_-2.*e2_-2.*s2_*e2_;
double det = 16.*( -L*sqr(xT)+pow(xT,4)*s2_+2.*xg*sqr(xT)*(1.-s2_-e2_)+
L*sqr(xg)-sqr(xg*xT)*(1.+s2_)+pow(xg,4)+
2.*pow(xg,3)*(-1.+s2_+e2_) );
if (det<0.) return false;
if (j==0) xs = (-B+sqrt(det))/(2.*A);
if (j==1) xs = (-B-sqrt(det))/(2.*A);
// check value of xs is physical
if (xs>(1.+s2_-e2_) || xs<2.*s_) return false;
// calculate xe
xe = 2.-xs-xg;
// check value of xe is physical
if (xe>(1.+e2_-s2_) || xe<2.*e_) return false;
// calculate xe_z
double root1 = sqrt(max(0.,sqr(xs)-4.*s2_)), root2 = sqrt(max(0.,sqr(xe)-4.*e2_-sqr(xT)));
double epsilon_p = -root1+xT*sinh(y)+root2;
double epsilon_m = -root1+xT*sinh(y)-root2;
// find direction of emitter
if (fabs(epsilon_p) < 1.e-10) xe_z = sqrt(sqr(xe)-4.*e2_-sqr(xT));
else if (fabs(epsilon_m) < 1.e-10) xe_z = -sqrt(sqr(xe)-4.*e2_-sqr(xT));
else return false;
// check the emitter is on shell
if (fabs((sqr(xe)-sqr(xT)-sqr(xe_z)-4.*e2_))>1.e-10) return false;
// calculate 4 momenta
particleMomenta[0].setE ( mb_);
particleMomenta[0].setX ( ZERO);
particleMomenta[0].setY ( ZERO);
particleMomenta[0].setZ ( ZERO);
particleMomenta[0].setMass( mb_);
particleMomenta[1].setE ( mb_*xe/2.);
particleMomenta[1].setX (-pT*cos(phi));
particleMomenta[1].setY (-pT*sin(phi));
particleMomenta[1].setZ ( mb_*xe_z/2.);
particleMomenta[1].setMass( mb_*e_);
particleMomenta[2].setE ( mb_*xs/2.);
particleMomenta[2].setX ( ZERO);
particleMomenta[2].setY ( ZERO);
particleMomenta[2].setZ (-mb_*sqrt(sqr(xs)-4.*s2_)/2.);
particleMomenta[2].setMass( mb_*s_);
particleMomenta[3].setE ( pT*cosh(y));
particleMomenta[3].setX ( pT*cos(phi));
particleMomenta[3].setY ( pT*sin(phi));
particleMomenta[3].setZ ( pT*sinh(y));
particleMomenta[3].setMass( ZERO);
return true;
}
bool PerturbativeDecayer::psCheck(const double xg, const double xs) {
// check is point is in allowed region of phase space
double xe_star = (1.-s2_+e2_-xg)/sqrt(1.-xg);
double xg_star = xg/sqrt(1.-xg);
if ((sqr(xe_star)-4.*e2_) < 1e-10) return false;
double xs_max = (4.+4.*s2_-sqr(xe_star+xg_star)+
sqr(sqrt(sqr(xe_star)-4.*e2_)+xg_star))/ 4.;
double xs_min = (4.+4.*s2_-sqr(xe_star+xg_star)+
sqr(sqrt(sqr(xe_star)-4.*e2_)-xg_star))/ 4.;
if (xs < xs_min || xs > xs_max) return false;
return true;
}
InvEnergy2 PerturbativeDecayer::calculateDipole(const DipoleType & dipoleId,
const Particle & inpart,
const ParticleVector & decay3) {
// calculate dipole for decay b->ac
InvEnergy2 dipole = ZERO;
double x1 = 2.*decay3[0]->momentum().e()/mb_;
double x2 = 2.*decay3[1]->momentum().e()/mb_;
double xg = 2.*decay3[2]->momentum().e()/mb_;
double mu12 = sqr(decay3[0]->mass()/mb_);
double mu22 = sqr(decay3[1]->mass()/mb_);
tcPDPtr part[3] = {inpart.dataPtr(),decay3[0]->dataPtr(),decay3[1]->dataPtr()};
if(dipoleId.type==FFc || dipoleId.type == IFc || dipoleId.type == IFbc) {
swap(part[1],part[2]);
swap(x1,x2);
swap(mu12,mu22);
}
// radiation from b with initial-final connection
if (dipoleId.type==IFba || dipoleId.type==IFbc) {
dipole = -2./sqr(mb_*xg);
dipole *= colourCoeff(part[0],part[1],part[2],dipoleId);
}
// radiation from a/c with initial-final connection
else if (dipoleId.type==IFa || dipoleId.type==IFc) {
double z = 1. - xg/(1.-mu22+mu12);
dipole = (-2.*mu12/sqr(1.-x2+mu22-mu12)/sqr(mb_) + (1./(1.-x2+mu22-mu12)/sqr(mb_))*
(2./(1.-z)-dipoleSpinFactor(part[1],z)));
dipole *= colourCoeff(part[1],part[0],part[2],dipoleId);
}
// radiation from a/c with final-final connection
else if (dipoleId.type==FFa || dipoleId.type==FFc) {
double z = 1. + ((x1-1.+mu22-mu12)/(x2-2.*mu22));
double y = (1.-x2-mu12+mu22)/(1.-mu12-mu22);
double vt = sqrt((1.-sqr(e_+s_))*(1.-sqr(e_-s_)))/(1.-mu12-mu22);
double v = sqrt(sqr(2.*mu22+(1.-mu12-mu22)*(1.-y))-4.*mu22)
/(1.-y)/(1.-mu12-mu22);
if(part[1]->iSpin()!=PDT::Spin1) {
dipole = (1./(1.-x2+mu22-mu12)/sqr(mb_))*
((2./(1.-z*(1.-y)))-vt/v*(dipoleSpinFactor(part[1],z)+(2.*mu12/(1.+mu22-mu12-x2))));
}
else {
dipole = (1./(1.-x2+mu22-mu12)/sqr(mb_))*
(1./(1.-z*(1.-y))+1./(1.-(1.-z)*(1.-y))+(z*(1.-z)-2.)/v-vt/v*(2.*mu12/(1.+mu22-mu12-x2)));
}
dipole *= colourCoeff(part[1],part[2],part[0],dipoleId);
}
// coupling prefactors
dipole *= 8.*Constants::pi;
if(dipoleId.interaction==ShowerInteraction::QCD)
dipole *= alphaS() ->value(mb_*mb_);
else
dipole *= alphaEM()->value(mb_*mb_);
// return the answer
return dipole;
}
double PerturbativeDecayer::dipoleSpinFactor(tcPDPtr part, double z){
// calculate the spin dependent component of the dipole
if (part->iSpin()==PDT::Spin0)
return 2.;
else if (part->iSpin()==PDT::Spin1Half)
return (1. + z);
else if (part->iSpin()==PDT::Spin1)
return -(z*(1.-z) - 1./(1.-z) + 1./z -2.);
return 0.;
}
double PerturbativeDecayer::colourCoeff(tcPDPtr emitter,
tcPDPtr spectator,
tcPDPtr other,
DipoleType dipole) {
if(dipole.interaction==ShowerInteraction::QCD) {
// calculate the colour factor of the dipole
double numerator=1.;
double denominator=1.;
if (emitter->iColour()!=PDT::Colour0 &&
spectator->iColour()!=PDT::Colour0 &&
other->iColour()!=PDT::Colour0) {
if (emitter->iColour() ==PDT::Colour3 ||
emitter->iColour() ==PDT::Colour3bar) numerator=-4./3;
else if (emitter->iColour() ==PDT::Colour8) numerator=-3. ;
denominator=-1.*numerator;
if (spectator->iColour()==PDT::Colour3 ||
spectator->iColour()==PDT::Colour3bar) numerator-=4./3;
else if (spectator->iColour()==PDT::Colour8) numerator-=3. ;
if (other->iColour() ==PDT::Colour3 ||
other->iColour() ==PDT::Colour3bar) numerator+=4./3;
else if (other->iColour() ==PDT::Colour8) numerator+=3. ;
numerator*=(-1./2.);
}
if (emitter->iColour()==PDT::Colour3 ||
emitter->iColour()== PDT::Colour3bar) numerator*=4./3.;
else if (emitter->iColour()==PDT::Colour8 &&
spectator->iColour()!=PDT::Colour8) numerator*=3.;
else if (emitter->iColour()==PDT::Colour8 &&
spectator->iColour()==PDT::Colour8) numerator*=6.;
return (numerator/denominator);
}
else {
double val = double(emitter->iCharge()*spectator->iCharge())/9.;
// FF dipoles
if(dipole.type==FFa || dipole.type == FFc) {
return val;
}
else {
return -val;
}
}
}
void PerturbativeDecayer::getColourLines(RealEmissionProcessPtr real) {
// extract the particles
vector<PPtr> branchingPart;
branchingPart.push_back(real->incoming()[0]);
for(unsigned int ix=0;ix<real->outgoing().size();++ix) {
branchingPart.push_back(real->outgoing()[ix]);
}
vector<unsigned int> sing,trip,atrip,oct;
for (size_t ib=0;ib<branchingPart.size()-1;++ib) {
if (branchingPart[ib]->dataPtr()->iColour()==PDT::Colour0 ) sing. push_back(ib);
else if(branchingPart[ib]->dataPtr()->iColour()==PDT::Colour3 ) trip. push_back(ib);
else if(branchingPart[ib]->dataPtr()->iColour()==PDT::Colour3bar) atrip.push_back(ib);
else if(branchingPart[ib]->dataPtr()->iColour()==PDT::Colour8 ) oct. push_back(ib);
}
// decaying colour singlet
if (branchingPart[0]->dataPtr()->iColour()==PDT::Colour0) {
// 0 -> 3 3bar
if (trip.size()==1 && atrip.size()==1) {
if(real->interaction()==ShowerInteraction::QCD) {
branchingPart[atrip[0]]->colourConnect(branchingPart[ 3 ]);
branchingPart[ 3 ]->colourConnect(branchingPart[trip[0]]);
}
else {
branchingPart[atrip[0]]->colourConnect(branchingPart[trip[0]]);
}
}
// 0 -> 8 8
else if (oct.size()==2 ) {
if(real->interaction()==ShowerInteraction::QCD) {
bool col = UseRandom::rndbool();
branchingPart[oct[0]]->colourConnect(branchingPart[ 3 ],col);
branchingPart[ 3 ]->colourConnect(branchingPart[oct[1]],col);
branchingPart[oct[1]]->colourConnect(branchingPart[oct[0]],col);
}
else {
branchingPart[oct[0]]->colourConnect(branchingPart[oct[1]]);
branchingPart[oct[1]]->colourConnect(branchingPart[oct[0]]);
}
}
else
assert(real->interaction()==ShowerInteraction::QED);
}
// decaying colour triplet
else if (branchingPart[0]->dataPtr()->iColour()==PDT::Colour3 ){
// 3 -> 3 0
if (trip.size()==2 && sing.size()==1) {
if(real->interaction()==ShowerInteraction::QCD) {
branchingPart[3]->incomingColour(branchingPart[trip[0]]);
branchingPart[3]-> colourConnect(branchingPart[trip[1]]);
}
else {
branchingPart[trip[1]]->incomingColour(branchingPart[trip[0]]);
}
} // 3 -> 3 8
else if (trip.size()==2 && oct.size()==1) {
if(real->interaction()==ShowerInteraction::QCD) {
// 8 emit incoming partner
if(real->emitter()==oct[0]&&real->spectator()==0) {
branchingPart[ 3 ]->incomingColour(branchingPart[trip[0]]);
branchingPart[ 3 ]-> colourConnect(branchingPart[oct[0] ]);
branchingPart[oct[0]]-> colourConnect(branchingPart[trip[1]]);
}
// 8 emit final spectator or vice veras
else {
branchingPart[oct[0]]->incomingColour(branchingPart[trip[0]]);
branchingPart[oct[0]]-> colourConnect(branchingPart[ 3 ]);
branchingPart[ 3 ]-> colourConnect(branchingPart[trip[1]]);
}
}
else {
branchingPart[oct[0]]->incomingColour(branchingPart[trip[0]]);
branchingPart[oct[0]]-> colourConnect(branchingPart[trip[1]]);
}
}
else
assert(false);
}
// decaying colour anti-triplet
else if (branchingPart[0]->dataPtr()->iColour()==PDT::Colour3bar) {
// 3bar -> 3bar 0
if (atrip.size()==2 && sing.size()==1) {
if(real->interaction()==ShowerInteraction::QCD) {
branchingPart[3]->incomingColour(branchingPart[atrip[0]],true);
branchingPart[3]-> colourConnect(branchingPart[atrip[1]],true);
}
else {
branchingPart[atrip[1]]->incomingColour(branchingPart[atrip[0]],true);
}
}
// 3 -> 3 8
else if (atrip.size()==2 && oct.size()==1){
if(real->interaction()==ShowerInteraction::QCD) {
// 8 emit incoming partner
if(real->emitter()==oct[0]&&real->spectator()==0) {
branchingPart[ 3 ]->incomingColour(branchingPart[atrip[0]],true);
branchingPart[ 3 ]-> colourConnect(branchingPart[oct[0] ],true);
branchingPart[oct[0]]-> colourConnect(branchingPart[atrip[1]],true);
}
// 8 emit final spectator or vice veras
else {
if(real->interaction()==ShowerInteraction::QCD) {
branchingPart[oct[0]]->incomingColour(branchingPart[atrip[0]],true);
branchingPart[oct[0]]-> colourConnect(branchingPart[ 3 ],true);
branchingPart[3]-> colourConnect(branchingPart[atrip[1]] ,true);
}
}
}
else {
branchingPart[oct[0]]->incomingColour(branchingPart[atrip[0]],true);
branchingPart[oct[0]]-> colourConnect(branchingPart[atrip[1]],true);
}
}
else
assert(false);
}
// decaying colour octet
else if(branchingPart[0]->dataPtr()->iColour()==PDT::Colour8 ) {
// 8 -> 3 3bar
if (trip.size()==1 && atrip.size()==1) {
if(real->interaction()==ShowerInteraction::QCD) {
// 3 emits
if(trip[0]==real->emitter()) {
branchingPart[3] ->incomingColour(branchingPart[oct[0]] );
branchingPart[3] -> colourConnect(branchingPart[trip[0]]);
branchingPart[atrip[0]]->incomingColour(branchingPart[oct[0]],true);
}
// 3bar emits
else {
branchingPart[3] ->incomingColour(branchingPart[oct[0]] ,true);
branchingPart[3] -> colourConnect(branchingPart[atrip[0]],true);
branchingPart[trip[0]]->incomingColour(branchingPart[oct[0]] );
}
}
else {
branchingPart[trip[0]]->incomingColour(branchingPart[oct[0]] );
branchingPart[atrip[0]]->incomingColour(branchingPart[oct[0]],true);
}
}
// 8 -> 8 0
else if (sing.size()==1 && oct.size()==2) {
if(real->interaction()==ShowerInteraction::QCD) {
bool col = UseRandom::rndbool();
branchingPart[ 3 ]->colourConnect (branchingPart[oct[1]], col);
branchingPart[ 3 ]->incomingColour(branchingPart[oct[0]], col);
branchingPart[oct[1]]->incomingColour(branchingPart[oct[0]],!col);
}
else {
branchingPart[oct[1]]->incomingColour(branchingPart[oct[0]]);
branchingPart[oct[1]]->incomingColour(branchingPart[oct[0]],true);
}
}
else
assert(false);
}
}
PerturbativeDecayer::phaseSpaceRegion
PerturbativeDecayer::inInitialFinalDeadZone(double xg, double xa,
double a, double c) const {
double lam = sqrt(1.+a*a+c*c-2.*a-2.*c-2.*a*c);
double kappab = 1.+0.5*(1.-a+c+lam);
double kappac = kappab-1.+c;
double kappa(0.);
// check whether or not in the region for emission from c
double r = 0.5;
if(c!=0.) r += 0.5*c/(1.+a-xa);
double pa = sqrt(sqr(xa)-4.*a);
double z = ((2.-xa)*(1.-r)+r*pa-xg)/pa;
if(z<1. && z>0.) {
kappa = (1.+a-c-xa)/(z*(1.-z));
if(kappa<kappac)
return emissionFromC;
}
// check in region for emission from b (T1)
double cq = sqr(1.+a-c)-4*a;
double bq = -2.*kappab*(1.-a-c);
double aq = sqr(kappab)-4.*a*(kappab-1);
double dis = sqr(bq)-4.*aq*cq;
z=1.-(-bq-sqrt(dis))/2./aq;
double w = 1.-(1.-z)*(kappab-1.);
double xgmax = (1.-z)*kappab;
// possibly in T1 region
if(xg<xgmax) {
z = 1.-xg/kappab;
kappa=kappab;
}
// possibly in T2 region
else {
aq = 4.*a;
bq = -4.*a*(2.-xg);
cq = sqr(1.+a-c-xg);
dis = sqr(bq)-4.*aq*cq;
z = (-bq-sqrt(dis))/2./aq;
kappa = xg/(1.-z);
}
// compute limit on xa
double u = 1.+a-c-(1.-z)*kappa;
w = 1.-(1.-z)*(kappa-1.);
double v = sqr(u)-4.*z*a*w;
if(v<0. && v>-1e-10) v= 0.;
v = sqrt(v);
if(xa<0.5*((u+v)/w+(u-v)/z))
return xg<xgmax ? emissionFromA1 : emissionFromA2;
else
return deadZone;
}
PerturbativeDecayer::phaseSpaceRegion
PerturbativeDecayer::inFinalFinalDeadZone(double xb, double xc,
double b, double c) const {
// basic kinematics
double lam = sqrt(1.+b*b+c*c-2.*b-2.*c-2.*b*c);
// check whether or not in the region for emission from b
double r = 0.5;
if(b!=0.) r+=0.5*b/(1.+c-xc);
double pc = sqrt(sqr(xc)-4.*c);
double z = -((2.-xc)*r-r*pc-xb)/pc;
if(z<1. and z>0.) {
if((1.-b+c-xc)/(z*(1.-z))<0.5*(1.+b-c+lam)) return emissionFromB;
}
// check whether or not in the region for emission from c
r = 0.5;
if(c!=0.) r+=0.5*c/(1.+b-xb);
double pb = sqrt(sqr(xb)-4.*b);
z = -((2.-xb)*r-r*pb-xc)/pb;
if(z<1. and z>0.) {
if((1.-c+b-xb)/(z*(1.-z))<0.5*(1.-b+c+lam)) return emissionFromC;
}
return deadZone;
}
bool PerturbativeDecayer::inTotalDeadZone(double xg, double xs,
const vector<DipoleType> & dipoles,
int i) {
double xb,xc,b,c;
if(dipoles[i].type==FFa || dipoles[i].type == IFa || dipoles[i].type == IFba) {
xc = xs;
xb = 2.-xg-xs;
b = e2_;
c = s2_;
}
else {
xb = xs;
xc = 2.-xg-xs;
b = s2_;
c = e2_;
}
for(unsigned int ix=0;ix<dipoles.size();++ix) {
if(dipoles[ix].interaction!=dipoles[i].interaction)
continue;
// should also remove negative QED dipoles but shouldn't be an issue unless we
// support QED ME corrections
switch (dipoles[ix].type) {
case FFa :
if(inFinalFinalDeadZone(xb,xc,b,c)!=deadZone) return false;
break;
case FFc :
if(inFinalFinalDeadZone(xc,xb,c,b)!=deadZone) return false;
break;
case IFa : case IFba:
if(inInitialFinalDeadZone(xg,xc,c,b)!=deadZone) return false;
break;
case IFc : case IFbc:
if(inInitialFinalDeadZone(xg,xb,b,c)!=deadZone) return false;
break;
}
}
return true;
}

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