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diff --git a/Shower/Dipole/SpinCorrelations/DipoleVertexRecord.cc b/Shower/Dipole/SpinCorrelations/DipoleVertexRecord.cc
--- a/Shower/Dipole/SpinCorrelations/DipoleVertexRecord.cc
+++ b/Shower/Dipole/SpinCorrelations/DipoleVertexRecord.cc
@@ -1,414 +1,416 @@
// -*- C++ -*-
//
// DipoleVertexRecord.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 2 of the GPL, see COPYING for details.
// Please respect the MCnet academic guidelines, see GUIDELINES for details.
//
//
// This is the implementation of the non-inlined, non-templated member
// functions of the DipoleVertexRecord class.
//
#include "DipoleVertexRecord.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/Helicity/FermionSpinInfo.h"
#include "ThePEG/Helicity/VectorSpinInfo.h"
#include "ThePEG/Helicity/WaveFunction/SpinorWaveFunction.h"
#include "ThePEG/Helicity/WaveFunction/VectorWaveFunction.h"
#include "ThePEG/EventRecord/HelicityVertex.h"
using namespace Herwig;
void DipoleVertexRecord::clear() {
// Clear all member variables
theCurrentEmitter.clear();
//theEmitterInfoRecord.clear();
theDecayParentSpinInfo = SpinPtr();
}
void DipoleVertexRecord::generatePhi(DipoleSplittingInfo& dInfo, Dipole& dip) {
// Set up the emitter spin info and its decay vertex
prepareSplitting(dInfo, dip);
// Compute the rho matrix (outgoing emitter) or decay matrix
// (incoming emitter) required to generate phi
PPtr emitter = dip.emitter(dInfo.configuration());
RhoDMatrix rho = emitterDensityMatrix(emitter);
// Compute the weights from the kernel
// Pair components A (int) and B (complex):
// weight = B*exp(i*A)
vector< pair<int, Complex> > wgts;
wgts = dInfo.splittingKernel()->generatePhi(dInfo,rho);
// Generate a value of phi
unsigned int nTry = 0;
double phi = 0.0;
double phiMax = 0.0;
double wgt = 0.0;
double wgtMax = 0.0;
static const Complex ii(0.,1.);
do {
phi = Constants::twopi*UseRandom::rnd();
Complex spinWgt = 0.;
for(unsigned int ix=0;ix<wgts.size();++ix) {
if(wgts[ix].first==0)
spinWgt += wgts[ix].second;
else
spinWgt += exp(double(wgts[ix].first)*ii*phi)*wgts[ix].second;
}
wgt = spinWgt.real();
// Store the phi with maximum weight in case there
// are too many failed attempts to generate phi.
if ( wgt>wgtMax ) {
phiMax = phi;
wgtMax = wgt;
}
nTry++;
}
// Accept / reject phi
while (wgt<UseRandom::rnd() && nTry < 10000);
if(nTry == 10000) {
phi = phiMax;
}
// Set the azimuthal angle in the splitting info
dInfo.lastPhi( phi );
// Set the matrix element of the emitter vertex
theCurrentEmitter.decayVertex()->ME(dInfo.splittingKernel()->matrixElement(dInfo));
}
void DipoleVertexRecord::prepareSplitting(const DipoleSplittingInfo& dInfo, const Dipole& dip ) {
// Extract the required information from the splitting info and dipole
PPtr emitter = dip.emitter(dInfo.configuration());
PPtr spectator = dip.spectator(dInfo.configuration());
// Get the pVector and nVector that define the decay frame
Lorentz5Momentum pVector = dInfo.splittingKinematics()->
pVector(emitter->momentum(), spectator->momentum(), dInfo);
Lorentz5Momentum nVector = dInfo.splittingKinematics()->
nVector(emitter->momentum(), spectator->momentum(), dInfo);
// Get the emitter and spectator directions
Helicity::Direction emmDir = dInfo.index().initialStateEmitter() ? incoming : outgoing;
Helicity::Direction specDir = dInfo.index().initialStateSpectator() ? incoming : outgoing;
// Create spinInfo if required (e.g. secondary processes)
if ( !emitter->spinInfo() )
createSpinInfo(emitter, emmDir);
if ( !spectator->spinInfo() )
createSpinInfo(spectator, specDir);
// Setup the emitter for spin correlation calculations
theCurrentEmitter.prepare(emitter, emmDir, specDir, pVector, nVector);
}
RhoDMatrix DipoleVertexRecord::emitterDensityMatrix(PPtr emitter) {
// Update the rho/decay matrices upto the emitter
emitter->spinInfo()->decay(true);
RhoDMatrix rho = emitter->spinInfo()->timelike() ?
emitter->spinInfo()->rhoMatrix() : emitter->spinInfo()->DMatrix();
// Map the rho/decay matrix to the decay frame
RhoDMatrix mapping = theCurrentEmitter.decayVertex()->mappingD2P();
RhoDMatrix rhop(rho.iSpin(),false);
if ( emitter->spinInfo()->timelike() ) {
for(int ixa=0;ixa<rho.iSpin();++ixa) {
for(int ixb=0;ixb<rho.iSpin();++ixb) {
for(int iya=0;iya<rho.iSpin();++iya) {
for(int iyb=0;iyb<rho.iSpin();++iyb) {
rhop(ixa,ixb) += rho(iya,iyb)*mapping(iya,ixa)*conj(mapping(iyb,ixb));
}
}
}
}
}
else {
for(int ixa=0;ixa<rho.iSpin();++ixa) {
for(int ixb=0;ixb<rho.iSpin();++ixb) {
for(int iya=0;iya<rho.iSpin();++iya) {
for(int iyb=0;iyb<rho.iSpin();++iyb) {
rhop(ixa,ixb) += rho(iya,iyb)*conj(mapping(iya,ixa))*mapping(iyb,ixb);
}
}
}
}
}
rhop.normalize();
return rhop;
}
void DipoleVertexRecord::update(const DipoleSplittingInfo& dInfo) {
// Get splitting particles.
PPtr oldEmitter = dInfo.emitter();
PPtr oldSpectator = dInfo.spectator();
PPtr newEmitter = dInfo.splitEmitter();
PPtr newSpectator = dInfo.splitSpectator();
PPtr emission = dInfo.emission();
assert(oldEmitter->spinInfo() && oldSpectator->spinInfo());
assert(!newEmitter->spinInfo() && !newSpectator->spinInfo() && !emission->spinInfo() );
// Create new emitter splitting info
Helicity::Direction emmDir = dInfo.index().initialStateEmitter() ? incoming : outgoing;
if ( abs(newEmitter->id()) <= 6 )
theCurrentEmitter.createNewFermionSpinInfo(newEmitter, emmDir);
else {
assert( newEmitter->id() == 21 );
theCurrentEmitter.createNewVectorSpinInfo(newEmitter, emmDir);
}
// Create new emission splitting info
if ( abs(emission->id()) <= 6 )
theCurrentEmitter.createNewFermionSpinInfo(emission, outgoing);
else {
assert( emission->id() == 21 );
theCurrentEmitter.createNewVectorSpinInfo(emission, outgoing);
}
// Initialise the emitter and emission decay matrices to delta matrices
initDecayMatrix(newEmitter,emmDir);
initDecayMatrix(emission, outgoing);
// Set the outgoing of the decay vertex
newEmitter->spinInfo()->productionVertex(theCurrentEmitter.decayVertex());
emission->spinInfo()->productionVertex(theCurrentEmitter.decayVertex());
// Develop the emitter
oldEmitter->spinInfo()->needsUpdate();
oldEmitter->spinInfo()->develop();
// Deal with spectators:
if ( !dInfo.index().incomingDecaySpectator() )
updateSpinInfo(oldSpectator, newSpectator);
// If the spectator is a decayed particle, don't want to do any transformations
else
newSpectator->spinInfo(oldSpectator->spinInfo());
// Tidy up
theCurrentEmitter.clear();
}
void DipoleVertexRecord::createSpinInfo(PPtr& part,
const Helicity::Direction& dir) {
// Identify the type of particle and use the appropriate function
// to create the spinInfo
if ( part->dataPtr()->iSpin() == PDT::Spin0 )
assert(false);
else if ( part->dataPtr()->iSpin() == PDT::Spin1Half )
createFermionSpinInfo(part, dir);
else if ( part->dataPtr()->iSpin() == PDT::Spin1 )
createVectorSpinInfo(part, dir);
else
assert(false);
}
void DipoleVertexRecord::createFermionSpinInfo(PPtr& part,
const Helicity::Direction& dir) {
// Create the spin info
const Lorentz5Momentum& partMom = part->momentum();
FermionSpinPtr fspin = new_ptr(FermionSpinInfo(partMom, dir==outgoing));
part->spinInfo(fspin);
// Calculate the basis for the particle in the lab frame
SpinorWaveFunction wave;
if(part->id()>0)
wave=SpinorWaveFunction(partMom, part->dataPtr(), incoming);
else
wave=SpinorWaveFunction(partMom, part->dataPtr(), outgoing);
// Store the basis states in the spin info
for(unsigned int ix=0;ix<2;++ix) {
wave.reset(ix);
LorentzSpinor<SqrtEnergy> basis = wave.dimensionedWave();
fspin->setBasisState(ix,basis);
}
}
void DipoleVertexRecord::createVectorSpinInfo(PPtr& part,
const Helicity::Direction& dir) {
// Create the spin info
const Lorentz5Momentum& partMom = part->momentum();
VectorSpinPtr vspin = new_ptr(VectorSpinInfo(partMom, dir==outgoing));
part->spinInfo(vspin);
// Calculate the basis for the particle in the lab frame
VectorWaveFunction wave(partMom, part->dataPtr(),
vspin->timelike() ? outgoing : incoming );
bool massless(part->id()==ParticleID::g||part->id()==ParticleID::gamma);
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();
}
// Store the basis states in the spin info
vspin->setBasisState(ix,basis);
}
}
void DipoleVertexRecord::updateSpinInfo( PPtr& oldPart,
PPtr& newPart ) {
// Copied from DipoleVertexRecord::updateSpinInfo,
// would be better to use a common function
const Lorentz5Momentum& oldMom = oldPart->momentum();
const Lorentz5Momentum& newMom = newPart->momentum();
// Rotation from old momentum to +ve z-axis
LorentzRotation oldToZAxis;
Axis axisOld(oldMom.vect().unit());
if( axisOld.perp2() > 1e-12 ) {
double sinth(sqrt(1.-sqr(axisOld.z())));
oldToZAxis.rotate( -acos(axisOld.z()),Axis(-axisOld.y()/sinth,axisOld.x()/sinth,0.));
}
// Rotation from new momentum to +ve z-axis
LorentzRotation newToZAxis;
Axis axisNew(newMom.vect().unit());
if( axisNew.perp2() > 1e-12 ) {
double sinth(sqrt(1.-sqr(axisNew.z())));
newToZAxis.rotate( -acos(axisNew.z()),Axis(-axisNew.y()/sinth,axisNew.x()/sinth,0.));
}
// Boost from old momentum to new momentum along z-axis
Lorentz5Momentum momOldRotated = oldToZAxis*Lorentz5Momentum(oldMom);
Lorentz5Momentum momNewRotated = newToZAxis*Lorentz5Momentum(newMom);
Energy2 a = sqr(momOldRotated.z()) + sqr(momNewRotated.t());
Energy2 b = 2.*momOldRotated.t()*momOldRotated.z();
Energy2 c = sqr(momOldRotated.t()) - sqr(momNewRotated.t());
double beta;
+ Energy4 disc2 = sqr(b)-4.*a*c;
+ Energy2 disc = sqrt(max(ZERO,disc2));
// The rotated momentum should always lie along the +ve z-axis
if ( momOldRotated.z() > ZERO )
- beta = (-b + sqrt(sqr(b)-4.*a*c)) / 2. / a;
+ beta = 0.5*(-b + disc) / a;
else
- beta = (-b - sqrt(sqr(b)-4.*a*c)) / 2. / a;
+ beta = 0.5*(-b - disc) / a;
LorentzRotation boostOldToNew(0., 0., beta);
// Total transform
LorentzRotation transform = (newToZAxis.inverse())*boostOldToNew*oldToZAxis;
// Assign the same spin info to the old and new particles
newPart->spinInfo(oldPart->spinInfo());
newPart->spinInfo()->transform(oldMom, transform);
}
void DipoleVertexRecord::prepareParticleDecay( const PPtr& decayIncoming ) {
// Need to set stopUpdate flag in the latest parent with spinInfo
PPtr parent = decayIncoming;
while ( !parent->spinInfo() )
parent = parent->parents()[0];
parent->spinInfo()->stopUpdate();
theDecayParentSpinInfo = parent->spinInfo();
}
void DipoleVertexRecord::updateParticleDecay() {
theDecayParentSpinInfo->needsUpdate();
theDecayParentSpinInfo->develop();
// Clear theDecayParentSpinInfo
theDecayParentSpinInfo = SpinPtr();
}
// Note: The develop function in SpinInfo.cc does not handle this properly
void DipoleVertexRecord::initDecayMatrix( PPtr& particle, Helicity::Direction dir ) {
// If not a vector boson, no extra considerations
if ( particle->dataPtr()->iSpin() != PDT::Spin1 )
particle->spinInfo()->develop();
// If particle is a vector boson
else {
// Massless is a special case:
if ( particle->id() == ParticleID::g || particle->id() == ParticleID::gamma ) {
if ( dir == outgoing ) {
particle->spinInfo()->DMatrix()(0,0) = 0.5;
particle->spinInfo()->DMatrix()(2,2) = 0.5;
}
else {
particle->spinInfo()->rhoMatrix()(0,0) = 0.5;
particle->spinInfo()->rhoMatrix()(2,2) = 0.5;
}
}
// Massive case is the default
else
particle->spinInfo()->develop();
}
}
// *** Attention *** The following static variable is needed for the type
// description in ThePEG. Please check that the template arguments
// are correct (the class and its base class), and that the constructor
// arguments are correct (the class name and the name of the dynamically
// loadable library where the class implementation can be found).
DescribeNoPIOClass<DipoleVertexRecord,Base>
describeHerwigDipoleVertexRecord("Herwig::DipoleVertexRecord", "DipoleVertexRecord.so");
void DipoleVertexRecord::Init() {
// *** Attention *** The following static variable is needed for the type
// description in ThePEG. Please check that the template arguments
// are correct (the class and its base class), and that the constructor
// arguments are correct (the class name and the name of the dynamically
// loadable library where the class implementation can be found).
static ClassDocumentation<DipoleVertexRecord> documentation
("There is no documentation for the DipoleVertexRecord class");
}

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