Page MenuHomeHEPForge
Files F7879812

No OneTemporary
Actions

View Options

diff --git a/Shower/Core/Base/ShowerParticle.cc b/Shower/Core/Base/ShowerParticle.cc
--- a/Shower/Core/Base/ShowerParticle.cc
+++ b/Shower/Core/Base/ShowerParticle.cc
@@ -1,586 +1,584 @@
// -*- C++ -*-
//
// ShowerParticle.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 ShowerParticle class.
//
#include "ShowerParticle.h"
#include "ThePEG/Interface/ClassDocumentation.h"
#include "ThePEG/Persistency/PersistentOStream.h"
#include "ThePEG/Persistency/PersistentIStream.h"
#include "ThePEG/Helicity/WaveFunction/SpinorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/SpinorBarWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/VectorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/ScalarWaveFunction.h"
#include <ostream>
using namespace Herwig;
PPtr ShowerParticle::clone() const {
return new_ptr(*this);
}
PPtr ShowerParticle::fullclone() const {
return new_ptr(*this);
}
ClassDescription<ShowerParticle> ShowerParticle::initShowerParticle;
// Definition of the static class description member.
void ShowerParticle::vetoEmission(ShowerPartnerType, Energy scale) {
scales_.QED = min(scale,scales_.QED );
scales_.QED_noAO = min(scale,scales_.QED_noAO );
scales_.QCD_c = min(scale,scales_.QCD_c );
scales_.QCD_c_noAO = min(scale,scales_.QCD_c_noAO );
scales_.QCD_ac = min(scale,scales_.QCD_ac );
scales_.QCD_ac_noAO = min(scale,scales_.QCD_ac_noAO);
}
void ShowerParticle::addPartner(EvolutionPartner in ) {
partners_.push_back(in);
}
namespace {
LorentzRotation boostToShower(Lorentz5Momentum & porig, tShowerBasisPtr basis) {
LorentzRotation output;
assert(basis);
if(basis->frame()==ShowerBasis::BackToBack) {
// we are doing the evolution in the back-to-back frame
// work out the boostvector
Boost boostv(-(basis->pVector()+basis->nVector()).boostVector());
// momentum of the parton
Lorentz5Momentum ptest(basis->pVector());
// construct the Lorentz boost
output = LorentzRotation(boostv);
ptest *= output;
Axis axis(ptest.vect().unit());
// now rotate so along the z axis as needed for the splitting functions
if(axis.perp2()>1e-10) {
double sinth(sqrt(1.-sqr(axis.z())));
output.rotate(-acos(axis.z()),Axis(-axis.y()/sinth,axis.x()/sinth,0.));
}
else if(axis.z()<0.) {
output.rotate(Constants::pi,Axis(1.,0.,0.));
}
porig = output*basis->pVector();
porig.setX(ZERO);
porig.setY(ZERO);
}
else {
output = LorentzRotation(-basis->pVector().boostVector());
porig = output*basis->pVector();
porig.setX(ZERO);
porig.setY(ZERO);
porig.setZ(ZERO);
}
return output;
}
RhoDMatrix bosonMapping(ShowerParticle & particle,
const Lorentz5Momentum & porig,
VectorSpinPtr vspin,
const LorentzRotation & rot,
Helicity::Direction dir) {
// rotate the original basis
vector<LorentzPolarizationVector> sbasis;
for(unsigned int ix=0;ix<3;++ix) {
sbasis.push_back(vspin->getProductionBasisState(ix));
sbasis.back().transform(rot);
}
// splitting basis
vector<LorentzPolarizationVector> fbasis;
bool massless(particle.id()==ParticleID::g||particle.id()==ParticleID::gamma);
VectorWaveFunction wave(porig,particle.dataPtr(),dir==outgoing ? incoming : outgoing);
for(unsigned int ix=0;ix<3;++ix) {
if(massless&&ix==1) {
fbasis.push_back(LorentzPolarizationVector());
}
else {
wave.reset(ix,vector_phase);
fbasis.push_back(wave.wave());
}
}
// work out the mapping
RhoDMatrix mapping=RhoDMatrix(PDT::Spin1,false);
for(unsigned int ix=0;ix<3;++ix) {
for(unsigned int iy=0;iy<3;++iy) {
mapping(ix,iy)= -conj(sbasis[ix].dot(fbasis[iy]));
- if((particle.id()<0 && dir==outgoing) ||
- (particle.id()>0 && dir==incoming) )
- mapping(ix,iy)=conj(mapping(ix,iy));
+ if(particle.id()<0) mapping(ix,iy)=conj(mapping(ix,iy));
}
}
return mapping;
}
RhoDMatrix fermionMapping(ShowerParticle & particle,
const Lorentz5Momentum & porig,
FermionSpinPtr fspin,
const LorentzRotation & rot) {
// extract the original basis states
vector<LorentzSpinor<SqrtEnergy> > sbasis;
for(unsigned int ix=0;ix<2;++ix) {
sbasis.push_back(fspin->getProductionBasisState(ix));
sbasis.back().transform(rot);
}
// calculate the states in the splitting basis
vector<LorentzSpinor<SqrtEnergy> > fbasis;
SpinorWaveFunction wave(porig,particle.dataPtr(),
particle.id()>0 ? incoming : outgoing);
for(unsigned int ix=0;ix<2;++ix) {
wave.reset(ix);
fbasis.push_back(wave.dimensionedWave());
}
RhoDMatrix mapping=RhoDMatrix(PDT::Spin1Half,false);
for(unsigned int ix=0;ix<2;++ix) {
if(fbasis[0].s2()==complex<SqrtEnergy>()) {
mapping(ix,0) = sbasis[ix].s3()/fbasis[0].s3();
mapping(ix,1) = sbasis[ix].s2()/fbasis[1].s2();
}
else {
mapping(ix,0) = sbasis[ix].s2()/fbasis[0].s2();
mapping(ix,1) = sbasis[ix].s3()/fbasis[1].s3();
}
}
return mapping;
}
FermionSpinPtr createFermionSpinInfo(ShowerParticle & particle,
const Lorentz5Momentum & porig,
const LorentzRotation & rot,
Helicity::Direction dir) {
// calculate the splitting basis for the branching
// and rotate back to construct the basis states
LorentzRotation rinv = rot.inverse();
SpinorWaveFunction wave;
if(particle.id()>0)
wave=SpinorWaveFunction(porig,particle.dataPtr(),incoming);
else
wave=SpinorWaveFunction(porig,particle.dataPtr(),outgoing);
FermionSpinPtr fspin = new_ptr(FermionSpinInfo(particle.momentum(),dir==outgoing));
for(unsigned int ix=0;ix<2;++ix) {
wave.reset(ix);
LorentzSpinor<SqrtEnergy> basis = wave.dimensionedWave();
basis.transform(rinv);
fspin->setBasisState(ix,basis);
fspin->setDecayState(ix,basis);
}
particle.spinInfo(fspin);
return fspin;
}
VectorSpinPtr createVectorSpinInfo(ShowerParticle & particle,
const Lorentz5Momentum & porig,
const LorentzRotation & rot,
Helicity::Direction dir) {
// calculate the splitting basis for the branching
// and rotate back to construct the basis states
LorentzRotation rinv = rot.inverse();
bool massless(particle.id()==ParticleID::g||particle.id()==ParticleID::gamma);
VectorWaveFunction wave(porig,particle.dataPtr(),dir);
VectorSpinPtr vspin = new_ptr(VectorSpinInfo(particle.momentum(),dir==outgoing));
for(unsigned int ix=0;ix<3;++ix) {
LorentzPolarizationVector basis;
if(massless&&ix==1) {
basis = LorentzPolarizationVector();
}
else {
wave.reset(ix,vector_phase);
basis = wave.wave();
}
basis *= rinv;
vspin->setBasisState(ix,basis);
vspin->setDecayState(ix,basis);
}
particle.spinInfo(vspin);
vspin-> DMatrix() = RhoDMatrix(PDT::Spin1);
vspin->rhoMatrix() = RhoDMatrix(PDT::Spin1);
if(massless) {
vspin-> DMatrix()(0,0) = 0.5;
vspin->rhoMatrix()(0,0) = 0.5;
vspin-> DMatrix()(2,2) = 0.5;
vspin->rhoMatrix()(2,2) = 0.5;
}
return vspin;
}
}
RhoDMatrix ShowerParticle::extractRhoMatrix(bool forward) {
// get the spin density matrix and the mapping
RhoDMatrix mapping;
SpinPtr inspin;
bool needMapping = getMapping(inspin,mapping);
// set the decayed flag
inspin->decay();
// get the spin density matrix
RhoDMatrix rho = forward ? inspin->rhoMatrix() : inspin->DMatrix();
// map to the shower basis if needed
if(needMapping) {
RhoDMatrix rhop(rho.iSpin(),false);
for(int ixb=0;ixb<rho.iSpin();++ixb) {
for(int iyb=0;iyb<rho.iSpin();++iyb) {
if(mapping(iyb,ixb)==0.)continue;
for(int iya=0;iya<rho.iSpin();++iya) {
if(rho(iya,iyb)==0.)continue;
for(int ixa=0;ixa<rho.iSpin();++ixa) {
rhop(ixa,ixb) += rho(iya,iyb)*mapping(iya,ixa)*conj(mapping(iyb,ixb));
}
}
}
}
rhop.normalize();
rho = rhop;
}
return rho;
}
bool ShowerParticle::getMapping(SpinPtr & output, RhoDMatrix & mapping) {
// if the particle is not from the hard process
if(!this->perturbative()) {
// mapping is the identity
output=this->spinInfo();
mapping=RhoDMatrix(this->dataPtr()->iSpin());
if(output) {
return false;
}
else {
Lorentz5Momentum porig;
LorentzRotation rot = boostToShower(porig,showerBasis());
Helicity::Direction dir = this->isFinalState() ? outgoing : incoming;
if(this->dataPtr()->iSpin()==PDT::Spin0) {
assert(false);
}
else if(this->dataPtr()->iSpin()==PDT::Spin1Half) {
output = createFermionSpinInfo(*this,porig,rot,dir);
}
else if(this->dataPtr()->iSpin()==PDT::Spin1) {
output = createVectorSpinInfo(*this,porig,rot,dir);
}
else {
assert(false);
}
return false;
}
}
// if particle is final-state and is from the hard process
else if(this->isFinalState()) {
assert(this->perturbative()==1 || this->perturbative()==2);
// get transform to shower frame
Lorentz5Momentum porig;
LorentzRotation rot = boostToShower(porig,showerBasis());
// the rest depends on the spin of the particle
PDT::Spin spin(this->dataPtr()->iSpin());
mapping=RhoDMatrix(spin,false);
// do the spin dependent bit
if(spin==PDT::Spin0) {
ScalarSpinPtr sspin=dynamic_ptr_cast<ScalarSpinPtr>(this->spinInfo());
if(!sspin) {
ScalarWaveFunction::constructSpinInfo(this,outgoing,true);
}
output=this->spinInfo();
return false;
}
else if(spin==PDT::Spin1Half) {
FermionSpinPtr fspin=dynamic_ptr_cast<FermionSpinPtr>(this->spinInfo());
// spin info exists get information from it
if(fspin) {
output=fspin;
mapping = fermionMapping(*this,porig,fspin,rot);
return true;
}
// spin info does not exist create it
else {
output = createFermionSpinInfo(*this,porig,rot,outgoing);
return false;
}
}
else if(spin==PDT::Spin1) {
VectorSpinPtr vspin=dynamic_ptr_cast<VectorSpinPtr>(this->spinInfo());
// spin info exists get information from it
if(vspin) {
output=vspin;
mapping = bosonMapping(*this,porig,vspin,rot,outgoing);
return true;
}
else {
output = createVectorSpinInfo(*this,porig,rot,outgoing);
return false;
}
}
// not scalar/fermion/vector
else
assert(false);
}
// incoming to hard process
else if(this->perturbative()==1 && !this->isFinalState()) {
// get the basis vectors
// get transform to shower frame
Lorentz5Momentum porig;
LorentzRotation rot = boostToShower(porig,showerBasis());
porig *= this->x();
// the rest depends on the spin of the particle
PDT::Spin spin(this->dataPtr()->iSpin());
mapping=RhoDMatrix(spin);
// do the spin dependent bit
if(spin==PDT::Spin0) {
cerr << "testing spin 0 not yet implemented " << endl;
assert(false);
}
// spin-1/2
else if(spin==PDT::Spin1Half) {
FermionSpinPtr fspin=dynamic_ptr_cast<FermionSpinPtr>(this->spinInfo());
// spin info exists get information from it
if(fspin) {
output=fspin;
mapping = fermionMapping(*this,porig,fspin,rot);
return true;
}
// spin info does not exist create it
else {
output = createFermionSpinInfo(*this,porig,rot,incoming);
return false;
}
}
// spin-1
else if(spin==PDT::Spin1) {
VectorSpinPtr vspin=dynamic_ptr_cast<VectorSpinPtr>(this->spinInfo());
// spinInfo exists map it
if(vspin) {
output=vspin;
mapping = bosonMapping(*this,porig,vspin,rot,incoming);
return true;
}
// create the spininfo
else {
output = createVectorSpinInfo(*this,porig,rot,incoming);
return false;
}
}
assert(false);
}
// incoming to decay
else if(this->perturbative() == 2 && !this->isFinalState()) {
// get the basis vectors
Lorentz5Momentum porig;
LorentzRotation rot=boostToShower(porig,showerBasis());
// the rest depends on the spin of the particle
PDT::Spin spin(this->dataPtr()->iSpin());
mapping=RhoDMatrix(spin);
// do the spin dependent bit
if(spin==PDT::Spin0) {
cerr << "testing spin 0 not yet implemented " << endl;
assert(false);
}
// spin-1/2
else if(spin==PDT::Spin1Half) {
// FermionSpinPtr fspin=dynamic_ptr_cast<FermionSpinPtr>(this->spinInfo());
// // spin info exists get information from it
// if(fspin) {
// output=fspin;
// mapping = fermionMapping(*this,porig,fspin,rot);
// return true;
// // spin info does not exist create it
// else {
// output = createFermionSpinInfo(*this,porig,rot,incoming);
// return false;
// }
// }
assert(false);
}
// // spin-1
// else if(spin==PDT::Spin1) {
// VectorSpinPtr vspin=dynamic_ptr_cast<VectorSpinPtr>(this->spinInfo());
// // spinInfo exists map it
// if(vspin) {
// output=vspin;
// mapping = bosonMapping(*this,porig,vspin,rot);
// return true;
// }
// // create the spininfo
// else {
// output = createVectorSpinInfo(*this,porig,rot,incoming);
// return false;
// }
// }
// assert(false);
assert(false);
}
else
assert(false);
return true;
}
void ShowerParticle::constructSpinInfo(bool timeLike) {
// now construct the required spininfo and calculate the basis states
PDT::Spin spin(dataPtr()->iSpin());
if(spin==PDT::Spin0) {
ScalarWaveFunction::constructSpinInfo(this,outgoing,timeLike);
}
// calculate the basis states and construct the SpinInfo for a spin-1/2 particle
else if(spin==PDT::Spin1Half) {
// outgoing particle
if(id()>0) {
vector<LorentzSpinorBar<SqrtEnergy> > stemp;
SpinorBarWaveFunction::calculateWaveFunctions(stemp,this,outgoing);
SpinorBarWaveFunction::constructSpinInfo(stemp,this,outgoing,timeLike);
}
// outgoing antiparticle
else {
vector<LorentzSpinor<SqrtEnergy> > stemp;
SpinorWaveFunction::calculateWaveFunctions(stemp,this,outgoing);
SpinorWaveFunction::constructSpinInfo(stemp,this,outgoing,timeLike);
}
}
// calculate the basis states and construct the SpinInfo for a spin-1 particle
else if(spin==PDT::Spin1) {
bool massless(id()==ParticleID::g||id()==ParticleID::gamma);
vector<Helicity::LorentzPolarizationVector> vtemp;
VectorWaveFunction::calculateWaveFunctions(vtemp,this,outgoing,massless,vector_phase);
VectorWaveFunction::constructSpinInfo(vtemp,this,outgoing,timeLike,massless);
}
else {
throw Exception() << "Spins higher than 1 are not yet implemented in "
<< "FS_QtildaShowerKinematics1to2::constructVertex() "
<< Exception::runerror;
}
}
void ShowerParticle::initializeDecay() {
Lorentz5Momentum p, n, ppartner, pcm;
assert(perturbative()!=1);
// this is for the initial decaying particle
if(perturbative()==2) {
ShowerBasisPtr newBasis;
p = momentum();
Lorentz5Momentum ppartner(partner()->momentum());
// removed to make inverse recon work properly
//if(partner->thePEGBase()) ppartner=partner->thePEGBase()->momentum();
pcm=ppartner;
Boost boost(p.findBoostToCM());
pcm.boost(boost);
n = Lorentz5Momentum( ZERO,0.5*p.mass()*pcm.vect().unit());
n.boost( -boost);
newBasis = new_ptr(ShowerBasis());
newBasis->setBasis(p,n,ShowerBasis::Rest);
showerBasis(newBasis,false);
}
else {
showerBasis(dynamic_ptr_cast<ShowerParticlePtr>(parents()[0])->showerBasis(),true);
}
}
void ShowerParticle::initializeInitialState(PPtr parent) {
// For the time being we are considering only 1->2 branching
Lorentz5Momentum p, n, pthis, pcm;
assert(perturbative()!=2);
if(perturbative()==1) {
ShowerBasisPtr newBasis;
// find the partner and its momentum
if(!partner()) return;
if(partner()->isFinalState()) {
Lorentz5Momentum pa = -momentum()+partner()->momentum();
Lorentz5Momentum pb = momentum();
Energy scale=parent->momentum().t();
Lorentz5Momentum pbasis(ZERO,parent->momentum().vect().unit()*scale);
Axis axis(pa.vect().unit());
LorentzRotation rot;
double sinth(sqrt(sqr(axis.x())+sqr(axis.y())));
if(axis.perp2()>1e-20) {
rot.setRotate(-acos(axis.z()),Axis(-axis.y()/sinth,axis.x()/sinth,0.));
rot.rotateX(Constants::pi);
}
if(abs(1.-pa.e()/pa.vect().mag())>1e-6) rot.boostZ( pa.e()/pa.vect().mag());
pb *= rot;
if(pb.perp2()/GeV2>1e-20) {
Boost trans = -1./pb.e()*pb.vect();
trans.setZ(0.);
rot.boost(trans);
}
pbasis *=rot;
rot.invert();
n = rot*Lorentz5Momentum(ZERO,-pbasis.vect());
p = rot*Lorentz5Momentum(ZERO, pbasis.vect());
}
else {
pcm = parent->momentum();
p = Lorentz5Momentum(ZERO, pcm.vect());
n = Lorentz5Momentum(ZERO, -pcm.vect());
}
newBasis = new_ptr(ShowerBasis());
newBasis->setBasis(p,n,ShowerBasis::BackToBack);
showerBasis(newBasis,false);
}
else {
showerBasis(dynamic_ptr_cast<ShowerParticlePtr>(children()[0])->showerBasis(),true);
}
}
void ShowerParticle::initializeFinalState() {
// set the basis vectors
Lorentz5Momentum p,n;
if(perturbative()!=0) {
ShowerBasisPtr newBasis;
// find the partner() and its momentum
if(!partner()) return;
Lorentz5Momentum ppartner(partner()->momentum());
// momentum of the emitting particle
p = momentum();
Lorentz5Momentum pcm;
// if the partner is a final-state particle then the reference
// vector is along the partner in the rest frame of the pair
if(partner()->isFinalState()) {
Boost boost=(p + ppartner).findBoostToCM();
pcm = ppartner;
pcm.boost(boost);
n = Lorentz5Momentum(ZERO,pcm.vect());
n.boost( -boost);
}
else if(!partner()->isFinalState()) {
// if the partner is an initial-state particle then the reference
// vector is along the partner which should be massless
if(perturbative()==1) {
n = Lorentz5Momentum(ZERO,ppartner.vect());
}
// if the partner is an initial-state decaying particle then the reference
// vector is along the backwards direction in rest frame of decaying particle
else {
Boost boost=ppartner.findBoostToCM();
pcm = p;
pcm.boost(boost);
n = Lorentz5Momentum( ZERO, -pcm.vect());
n.boost( -boost);
}
}
newBasis = new_ptr(ShowerBasis());
newBasis->setBasis(p,n,ShowerBasis::BackToBack);
showerBasis(newBasis,false);
}
else if(initiatesTLS()) {
showerBasis(dynamic_ptr_cast<ShowerParticlePtr>(parents()[0]->children()[0])->showerBasis(),true);
}
else {
showerBasis(dynamic_ptr_cast<ShowerParticlePtr>(parents()[0])->showerBasis(),true);
}
}
void ShowerParticle::setShowerMomentum(bool timeLike) {
Energy m = this->mass() > ZERO ? this->mass() : this->data().mass();
// calculate the momentum of the assuming on-shell
Energy2 pt2 = sqr(this->showerParameters().pt);
double alpha = timeLike ? this->showerParameters().alpha : this->x();
double beta = 0.5*(sqr(m) + pt2 - sqr(alpha)*showerBasis()->pVector().m2())/(alpha*showerBasis()->p_dot_n());
Lorentz5Momentum porig=showerBasis()->sudakov2Momentum(alpha,beta,
this->showerParameters().ptx,
this->showerParameters().pty);
porig.setMass(m);
this->set5Momentum(porig);
}

File Metadata

Mime Type
text/x-diff
Expires
Tue, Nov 19, 9:07 PM (1 d, 35 m)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
3806204
Default Alt Text
(19 KB)

Event Timeline