QTildeShowerHandler.cc
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QTildeShowerHandler.cc
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	// -- C++ --
	//
	// This is the implementation of the non-inlined, non-templated member
	// functions of the QTildeShowerHandler class.
	//

	#include "QTildeShowerHandler.h"
	#include "ThePEG/Interface/ClassDocumentation.h"
	#include "ThePEG/Interface/Switch.h"
	#include "ThePEG/Interface/Reference.h"
	#include "ThePEG/Interface/RefVector.h"
	#include "ThePEG/Interface/Parameter.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/Utilities/EnumIO.h"
	#include "Herwig/Shower/QTilde/Base/ShowerParticle.h"
	#include "Herwig/PDF/MPIPDF.h"
	#include "Herwig/PDF/MinBiasPDF.h"
	#include "Herwig/Shower/QTilde/Base/ShowerTree.h"
	#include "Herwig/Shower/QTilde/Base/KinematicsReconstructor.h"
	#include "Herwig/Shower/QTilde/Base/PartnerFinder.h"
	#include "Herwig/PDF/HwRemDecayer.h"
	#include "Herwig/Shower/QTilde/Base/ShowerVertex.h"
	#include "ThePEG/Repository/CurrentGenerator.h"
	#include "Herwig/MatrixElement/Matchbox/Base/SubtractedME.h"
	#include "Herwig/MatrixElement/Matchbox/MatchboxFactory.h"
	#include "ThePEG/PDF/PartonExtractor.h"
	#include "Herwig/Shower/RealEmissionProcess.h"

	using namespace Herwig;

	namespace {

	/**
	* A struct to order the particles in the same way as in the DecayMode's
	*/
	struct ParticleOrdering {
	/**
	* Operator for the ordering
	* @param p1 The first ParticleData object
	* @param p2 The second ParticleData object
	*/
	bool operator() (tcPDPtr p1, tcPDPtr p2) {
	return abs(p1->id()) > abs(p2->id()) \|\|
	( abs(p1->id()) == abs(p2->id()) && p1->id() > p2->id() ) \|\|
	( p1->id() == p2->id() && p1->fullName() > p2->fullName() );
	}
	};
	typedef multiset<tcPDPtr,ParticleOrdering> OrderedParticles;

	/**
	* Cached lookup of decay modes.
	* Generator::findDecayMode() is not efficient.
	*/
	tDMPtr findDecayMode(const string & tag) {
	static map<string,DMPtr> cache;
	map<string,DMPtr>::const_iterator pos = cache.find(tag);

	if ( pos != cache.end() )
	return pos->second;

	tDMPtr dm = CurrentGenerator::current().findDecayMode(tag);
	cache[tag] = dm;
	return dm;
	}
	}

	bool QTildeShowerHandler::_hardEmissionWarn = true;
	bool QTildeShowerHandler::_missingTruncWarn = true;

	QTildeShowerHandler::QTildeShowerHandler() :
	_maxtry(100), _meCorrMode(1), _reconOpt(0),
	_hardVetoReadOption(false),
	_iptrms(ZERO), _beta(0.), _gamma(ZERO), _iptmax(),
	_limitEmissions(0), _initialenhance(1.), _finalenhance(1.),
	interaction_(ShowerInteraction::Both),
	_trunc_Mode(true), _hardEmission(1),
	_spinOpt(1), _softOpt(2), _hardPOWHEG(false), muPt(ZERO),
	_maxTryFSR(100000), _maxFailFSR(100), _fracFSR(0.001),
	_nFSR(0), _nFailedFSR(0)
	{}

	QTildeShowerHandler::~QTildeShowerHandler() {}

	IBPtr QTildeShowerHandler::clone() const {
	return new_ptr(*this);
	}

	IBPtr QTildeShowerHandler::fullclone() const {
	return new_ptr(*this);
	}

	void QTildeShowerHandler::persistentOutput(PersistentOStream & os) const {
	os << _model << _splittingGenerator << _maxtry
	<< _meCorrMode << _hardVetoReadOption
	<< _limitEmissions << _spinOpt << _softOpt << _hardPOWHEG
	<< ounit(_iptrms,GeV) << _beta << ounit(_gamma,GeV) << ounit(_iptmax,GeV)
	<< _vetoes << _trunc_Mode << _hardEmission << _reconOpt
	<< ounit(muPt,GeV)
	<< oenum(interaction_) << _maxTryFSR << _maxFailFSR << _fracFSR;
	}

	void QTildeShowerHandler::persistentInput(PersistentIStream & is, int) {
	is >> _model >> _splittingGenerator >> _maxtry
	>> _meCorrMode >> _hardVetoReadOption
	>> _limitEmissions >> _spinOpt >> _softOpt >> _hardPOWHEG
	>> iunit(_iptrms,GeV) >> _beta >> iunit(_gamma,GeV) >> iunit(_iptmax,GeV)
	>> _vetoes >> _trunc_Mode >> _hardEmission >> _reconOpt
	>> iunit(muPt,GeV)
	>> ienum(interaction_) >> _maxTryFSR >> _maxFailFSR >> _fracFSR;
	}


	// The following static variable is needed for the type
	// description system in ThePEG.
	DescribeClass<QTildeShowerHandler,ShowerHandler>
	describeHerwigQTildeShowerHandler("Herwig::QTildeShowerHandler", "HwShower.so");

	void QTildeShowerHandler::Init() {

	static ClassDocumentation<QTildeShowerHandler> documentation
	("TheQTildeShowerHandler class is the main class"
	" for the angular-ordered parton shower",
	"The Shower evolution was performed using an algorithm described in "
	"\\cite{Marchesini:1983bm,Marchesini:1987cf,Gieseke:2003rz,Bahr:2008pv}.",
	"%\\cite{Marchesini:1983bm}\n"
	"\\bibitem{Marchesini:1983bm}\n"
	" G.~Marchesini and B.~R.~Webber,\n"
	" ``Simulation Of QCD Jets Including Soft Gluon Interference,''\n"
	" Nucl.\\ Phys.\\ B {\\bf 238}, 1 (1984).\n"
	" %%CITATION = NUPHA,B238,1;%%\n"
	"%\\cite{Marchesini:1987cf}\n"
	"\\bibitem{Marchesini:1987cf}\n"
	" G.~Marchesini and B.~R.~Webber,\n"
	" ``Monte Carlo Simulation of General Hard Processes with Coherent QCD\n"
	" Radiation,''\n"
	" Nucl.\\ Phys.\\ B {\\bf 310}, 461 (1988).\n"
	" %%CITATION = NUPHA,B310,461;%%\n"
	"%\\cite{Gieseke:2003rz}\n"
	"\\bibitem{Gieseke:2003rz}\n"
	" S.~Gieseke, P.~Stephens and B.~Webber,\n"
	" ``New formalism for QCD parton showers,''\n"
	" JHEP {\\bf 0312}, 045 (2003)\n"
	" [arXiv:hep-ph/0310083].\n"
	" %%CITATION = JHEPA,0312,045;%%\n"
	);

	static Reference<QTildeShowerHandler,SplittingGenerator>
	interfaceSplitGen("SplittingGenerator",
	"A reference to the SplittingGenerator object",
	&Herwig::QTildeShowerHandler::_splittingGenerator,
	false, false, true, false);

	static Reference<QTildeShowerHandler,ShowerModel> interfaceShowerModel
	("ShowerModel",
	"The pointer to the object which defines the shower evolution model.",
	&QTildeShowerHandler::_model, false, false, true, false, false);

	static Parameter<QTildeShowerHandler,unsigned int> interfaceMaxTry
	("MaxTry",
	"The maximum number of attempts to generate the shower from a"
	" particular ShowerTree",
	&QTildeShowerHandler::_maxtry, 100, 1, 1000,
	false, false, Interface::limited);

	static Switch<QTildeShowerHandler, unsigned int> ifaceMECorrMode
	("MECorrMode",
	"Choice of the ME Correction Mode",
	&QTildeShowerHandler::_meCorrMode, 1, false, false);
	static SwitchOption on
	(ifaceMECorrMode,"Yes","hard+soft on", 1);
	static SwitchOption hard
	(ifaceMECorrMode,"Hard","only hard on", 2);
	static SwitchOption soft
	(ifaceMECorrMode,"Soft","only soft on", 3);

	static Switch<QTildeShowerHandler, bool> ifaceHardVetoReadOption
	("HardVetoReadOption",
	"Apply read-in scale veto to all collisions or just the primary one?",
	&QTildeShowerHandler::_hardVetoReadOption, false, false, false);
	static SwitchOption AllCollisions
	(ifaceHardVetoReadOption,
	"AllCollisions",
	"Read-in pT veto applied to primary and secondary collisions.",
	false);
	static SwitchOption PrimaryCollision
	(ifaceHardVetoReadOption,
	"PrimaryCollision",
	"Read-in pT veto applied to primary but not secondary collisions.",
	true);

	static Parameter<QTildeShowerHandler, Energy> ifaceiptrms
	("IntrinsicPtGaussian",
	"RMS of intrinsic pT of Gaussian distribution:\n"
	"2(1-Beta)exp(-sqr(intrinsicpT/RMS))/sqr(RMS)",
	&QTildeShowerHandler::_iptrms, GeV, ZERO, ZERO, 1000000.0*GeV,
	false, false, Interface::limited);

	static Parameter<QTildeShowerHandler, double> ifacebeta
	("IntrinsicPtBeta",
	"Proportion of inverse quadratic distribution in generating intrinsic pT.\n"
	"(1-Beta) is the proportion of Gaussian distribution",
	&QTildeShowerHandler::_beta, 0, 0, 1,
	false, false, Interface::limited);

	static Parameter<QTildeShowerHandler, Energy> ifacegamma
	("IntrinsicPtGamma",
	"Parameter for inverse quadratic:\n"
	"2BetaGamma/(sqr(Gamma)+sqr(intrinsicpT))",
	&QTildeShowerHandler::_gamma,GeV, ZERO, ZERO, 100000.0*GeV,
	false, false, Interface::limited);

	static Parameter<QTildeShowerHandler, Energy> ifaceiptmax
	("IntrinsicPtIptmax",
	"Upper bound on intrinsic pT for inverse quadratic",
	&QTildeShowerHandler::_iptmax,GeV, ZERO, ZERO, 100000.0*GeV,
	false, false, Interface::limited);

	static RefVector<QTildeShowerHandler,ShowerVeto> ifaceVetoes
	("Vetoes",
	"The vetoes to be checked during showering",
	&QTildeShowerHandler::_vetoes, -1,
	false,false,true,true,false);

	static Switch<QTildeShowerHandler,unsigned int> interfaceLimitEmissions
	("LimitEmissions",
	"Limit the number and type of emissions for testing",
	&QTildeShowerHandler::_limitEmissions, 0, false, false);
	static SwitchOption interfaceLimitEmissionsNoLimit
	(interfaceLimitEmissions,
	"NoLimit",
	"Allow an arbitrary number of emissions",
	0);
	static SwitchOption interfaceLimitEmissionsOneInitialStateEmission
	(interfaceLimitEmissions,
	"OneInitialStateEmission",
	"Allow one emission in the initial state and none in the final state",
	1);
	static SwitchOption interfaceLimitEmissionsOneFinalStateEmission
	(interfaceLimitEmissions,
	"OneFinalStateEmission",
	"Allow one emission in the final state and none in the initial state",
	2);
	static SwitchOption interfaceLimitEmissionsHardOnly
	(interfaceLimitEmissions,
	"HardOnly",
	"Only allow radiation from the hard ME correction",
	3);
	static SwitchOption interfaceLimitEmissionsOneEmission
	(interfaceLimitEmissions,
	"OneEmission",
	"Allow one emission in either the final state or initial state, but not both",
	4);

	static Switch<QTildeShowerHandler,bool> interfaceTruncMode
	("TruncatedShower", "Include the truncated shower?",
	&QTildeShowerHandler::_trunc_Mode, 1, false, false);
	static SwitchOption interfaceTruncMode0
	(interfaceTruncMode,"No","Truncated Shower is OFF", 0);
	static SwitchOption interfaceTruncMode1
	(interfaceTruncMode,"Yes","Truncated Shower is ON", 1);

	static Switch<QTildeShowerHandler,int> interfaceHardEmission
	("HardEmission",
	"Whether to use ME corrections or POWHEG for the hardest emission",
	&QTildeShowerHandler::_hardEmission, 0, false, false);
	static SwitchOption interfaceHardEmissionNone
	(interfaceHardEmission,
	"None",
	"No Corrections",
	0);
	static SwitchOption interfaceHardEmissionMECorrection
	(interfaceHardEmission,
	"MECorrection",
	"Old fashioned ME correction",
	1);
	static SwitchOption interfaceHardEmissionPOWHEG
	(interfaceHardEmission,
	"POWHEG",
	"Powheg style hard emission",
	2);

	static Switch<QTildeShowerHandler,ShowerInteraction::Type> interfaceInteractions
	("Interactions",
	"The interactions to be used in the shower",
	&QTildeShowerHandler::interaction_, ShowerInteraction::Both, false, false);
	static SwitchOption interfaceInteractionsQCD
	(interfaceInteractions,
	"QCD",
	"Only QCD radiation",
	ShowerInteraction::QCD);
	static SwitchOption interfaceInteractionsQED
	(interfaceInteractions,
	"QED",
	"Only QEd radiation",
	ShowerInteraction::QED);
	static SwitchOption interfaceInteractionsQCDandQED
	(interfaceInteractions,
	"QCDandQED",
	"Both QED and QCD radiation",
	ShowerInteraction::Both);

	static Switch<QTildeShowerHandler,unsigned int> interfaceReconstructionOption
	("ReconstructionOption",
	"Treatment of the reconstruction of the transverse momentum of "
	"a branching from the evolution scale.",
	&QTildeShowerHandler::_reconOpt, 0, false, false);
	static SwitchOption interfaceReconstructionOptionCutOff
	(interfaceReconstructionOption,
	"CutOff",
	"Use the cut-off masses in the calculation",
	0);
	static SwitchOption interfaceReconstructionOptionOffShell
	(interfaceReconstructionOption,
	"OffShell",
	"Use the off-shell masses in the calculation veto the emission of the parent,"
	" no veto in generation of emissions from children",
	1);
	static SwitchOption interfaceReconstructionOptionOffShell2
	(interfaceReconstructionOption,
	"OffShell2",
	"Use the off-shell masses in the calculation veto the emissions from the children."
	" no veto in generation of emissions from children",
	2);
	static SwitchOption interfaceReconstructionOptionOffShell3
	(interfaceReconstructionOption,
	"OffShell3",
	"Use the off-shell masses in the calculation veto the emissions from the children."
	" veto in generation of emissions from children using cut-off for second parton",
	3);

	static Switch<QTildeShowerHandler,unsigned int> interfaceSpinCorrelations
	("SpinCorrelations",
	"Treatment of spin correlations in the parton shower",
	&QTildeShowerHandler::_spinOpt, 1, false, false);
	static SwitchOption interfaceSpinCorrelationsOff
	(interfaceSpinCorrelations,
	"No",
	"No spin correlations",
	0);
	static SwitchOption interfaceSpinCorrelationsSpin
	(interfaceSpinCorrelations,
	"Yes",
	"Include the azimuthal spin correlations only",
	1);

	static Switch<QTildeShowerHandler,unsigned int> interfaceSoftCorrelations
	("SoftCorrelations",
	"Option for the treatment of soft correlations in the parton shower",
	&QTildeShowerHandler::_softOpt, 2, false, false);
	static SwitchOption interfaceSoftCorrelationsNone
	(interfaceSoftCorrelations,
	"No",
	"No soft correlations",
	0);
	static SwitchOption interfaceSoftCorrelationsFull
	(interfaceSoftCorrelations,
	"Full",
	"Use the full eikonal",
	1);
	static SwitchOption interfaceSoftCorrelationsSingular
	(interfaceSoftCorrelations,
	"Singular",
	"Use original Webber-Marchisini form",
	2);

	static Switch<QTildeShowerHandler,bool> interfaceHardPOWHEG
	("HardPOWHEG",
	"Treatment of powheg emissions which are too hard to have a shower interpretation",
	&QTildeShowerHandler::_hardPOWHEG, false, false, false);
	static SwitchOption interfaceHardPOWHEGAsShower
	(interfaceHardPOWHEG,
	"AsShower",
	"Still interpret as shower emissions",
	false);
	static SwitchOption interfaceHardPOWHEGRealEmission
	(interfaceHardPOWHEG,
	"RealEmission",
	"Generate shower from the real emmission configuration",
	true);

	static Parameter<QTildeShowerHandler,unsigned int> interfaceMaxTryFSR
	("MaxTryFSR",
	"The maximum number of attempted FSR emissions in"
	" the generation of the FSR",
	&QTildeShowerHandler::_maxTryFSR, 100000, 10, 100000000,
	false, false, Interface::limited);

	static Parameter<QTildeShowerHandler,unsigned int> interfaceMaxFailFSR
	("MaxFailFSR",
	"Maximum number of failures generating the FSR",
	&QTildeShowerHandler::_maxFailFSR, 100, 1, 100000000,
	false, false, Interface::limited);

	static Parameter<QTildeShowerHandler,double> interfaceFSRFailureFraction
	("FSRFailureFraction",
	"Maximum fraction of events allowed to fail due to too many FSR emissions",
	&QTildeShowerHandler::_fracFSR, 0.001, 1e-10, 1,
	false, false, Interface::limited);

	}

	tPPair QTildeShowerHandler::cascade(tSubProPtr sub,
	XCPtr xcomb) {
	// use me for reference in tex file etc
	useMe();
	prepareCascade(sub);
	// set things up in the base class
	resetWeights();
	hard_=ShowerTreePtr();
	decay_.clear();
	done_.clear();
	// check if anything needs doing
	if ( !doFSR() && ! doISR() )
	return sub->incoming();
	// start of the try block for the whole showering process
	unsigned int countFailures=0;
	while (countFailures<maxtry()) {
	try {
	decay_.clear();
	done_.clear();
	PerturbativeProcessPtr hard;
	DecayProcessMap decay;
	splitHardProcess(firstInteraction() ? tagged() :
	tPVector(currentSubProcess()->outgoing().begin(),
	currentSubProcess()->outgoing().end()),
	hard,decay);
	ShowerTree::constructTrees(hard_,decay_,hard,decay);
	// if no hard process
	if(!hard_) throw Exception() << "Shower starting with a decay"
	<< "is not implemented"
	<< Exception::runerror;
	// perform the shower for the hard process
	showerHardProcess(hard_,xcomb);
	done_.push_back(hard_);
	hard_->updateAfterShower(decay_);
	// if no decaying particles to shower break out of the loop
	if(decay_.empty()) break;
	// shower the decay products
	while(!decay_.empty()) {
	// find particle whose production process has been showered
	ShowerDecayMap::iterator dit = decay_.begin();
	while(!dit->second->parent()->hasShowered() && dit!=decay_.end()) ++dit;
	assert(dit!=decay_.end());
	// get the particle
	ShowerTreePtr decayingTree = dit->second;
	// remove it from the multimap
	decay_.erase(dit);
	// make sure the particle has been decayed
	QTildeShowerHandler::decay(decayingTree,decay_);
	// now shower the decay
	showerDecay(decayingTree);
	done_.push_back(decayingTree);
	decayingTree->updateAfterShower(decay_);
	}
	// suceeded break out of the loop
	break;
	}
	catch (KinematicsReconstructionVeto) {
	resetWeights();
	++countFailures;
	}
	}
	// if loop exited because of too many tries, throw event away
	if (countFailures >= maxtry()) {
	resetWeights();
	hard_=ShowerTreePtr();
	decay_.clear();
	done_.clear();
	throw Exception() << "Too many tries for main while loop "
	<< "in ShowerHandler::cascade()."
	<< Exception::eventerror;
	}
	//enter the particles in the event record
	fillEventRecord();
	// clear storage
	hard_=ShowerTreePtr();
	decay_.clear();
	done_.clear();
	// non hadronic case return
	if (!isResolvedHadron(incomingBeams().first ) &&
	!isResolvedHadron(incomingBeams().second) )
	return incomingBeams();
	// remake the remnants (needs to be after the colours are sorted
	// out in the insertion into the event record)
	if ( firstInteraction() ) return remakeRemnant(sub->incoming());
	//Return the new pair of incoming partons. remakeRemnant is not
	//necessary here, because the secondary interactions are not yet
	//connected to the remnants.
	return make_pair(findFirstParton(sub->incoming().first ),
	findFirstParton(sub->incoming().second));
	}

	void QTildeShowerHandler::fillEventRecord() {
	// create a new step
	StepPtr pstep = newStep();
	assert(!done_.empty());
	assert(done_[0]->isHard());
	// insert the steps
	for(unsigned int ix=0;ix<done_.size();++ix) {
	done_[ix]->fillEventRecord(pstep,doISR(),doFSR());
	}
	}

	HardTreePtr QTildeShowerHandler::generateCKKW(ShowerTreePtr ) const {
	return HardTreePtr();
	}

	void QTildeShowerHandler::doinit() {
	ShowerHandler::doinit();
	// interactions may have been changed through a setup file so we
	// clear it up here
	// calculate max no of FSR vetos
	_maxFailFSR = max(int(_maxFailFSR), int(_fracFSR*double(generator()->N())));
	}

	void QTildeShowerHandler::generateIntrinsicpT(vector<ShowerProgenitorPtr> particlesToShower) {
	_intrinsic.clear();
	if ( !ipTon() \|\| !doISR() ) return;
	// don't do anything for the moment for secondary scatters
	if( !firstInteraction() ) return;
	// generate intrinsic pT
	for(unsigned int ix=0;ix<particlesToShower.size();++ix) {
	// only consider initial-state particles
	if(particlesToShower[ix]->progenitor()->isFinalState()) continue;
	if(!particlesToShower[ix]->progenitor()->dataPtr()->coloured()) continue;
	Energy ipt;
	if(UseRandom::rnd() > _beta) {
	ipt=_iptrms*sqrt(-log(UseRandom::rnd()));
	}
	else {
	ipt=_gamma*sqrt(pow(1.+sqr(_iptmax/_gamma), UseRandom::rnd())-1.);
	}
	pair<Energy,double> pt = make_pair(ipt,UseRandom::rnd(Constants::twopi));
	_intrinsic[particlesToShower[ix]] = pt;
	}
	}

	void QTildeShowerHandler::setupMaximumScales(const vector<ShowerProgenitorPtr> & p,
	XCPtr xcomb) {
	// let POWHEG events radiate freely
	if(_hardEmission==2&&hardTree()) {
	vector<ShowerProgenitorPtr>::const_iterator ckt = p.begin();
	for (; ckt != p.end(); ckt++) (*ckt)->maxHardPt(Constants::MaxEnergy);
	return;
	}
	// return if no vetos
	if (!restrictPhasespace()) return;
	// find out if hard partonic subprocess.
	bool isPartonic(false);
	map<ShowerProgenitorPtr,ShowerParticlePtr>::const_iterator
	cit = _currenttree->incomingLines().begin();
	Lorentz5Momentum pcm;
	for(; cit!=currentTree()->incomingLines().end(); ++cit) {
	pcm += cit->first->progenitor()->momentum();
	isPartonic \|= cit->first->progenitor()->coloured();
	}
	// find minimum pt from hard process, the maximum pt from all outgoing
	// coloured lines (this is simpler and more general than
	// 2stu/(s^2+t^2+u^2)). Maximum scale for scattering processes will
	// be transverse mass.
	Energy ptmax = generator()->maximumCMEnergy();
	// general case calculate the scale
	if ( !hardScaleIsMuF() \|\| (hardVetoReadOption()&&!firstInteraction()) ) {
	// scattering process
	if(currentTree()->isHard()) {
	assert(xcomb);
	// coloured incoming particles
	if (isPartonic) {
	map<ShowerProgenitorPtr,tShowerParticlePtr>::const_iterator
	cjt = currentTree()->outgoingLines().begin();
	for(; cjt!=currentTree()->outgoingLines().end(); ++cjt) {
	if (cjt->first->progenitor()->coloured())
	ptmax = min(ptmax,cjt->first->progenitor()->momentum().mt());
	}
	}
	if (ptmax == generator()->maximumCMEnergy() ) ptmax = pcm.m();
	if(hardScaleIsMuF()&&hardVetoReadOption()&&
	!firstInteraction()) {
	ptmax=min(ptmax,sqrt(xcomb->lastShowerScale()));
	}
	}
	// decay, incoming() is the decaying particle.
	else {
	ptmax = currentTree()->incomingLines().begin()->first
	->progenitor()->momentum().mass();
	}
	}
	// hepeup.SCALUP is written into the lastXComb by the
	// LesHouchesReader itself - use this by user's choice.
	// Can be more general than this.
	else {
	if(currentTree()->isHard()) {
	assert(xcomb);
	ptmax = sqrt( xcomb->lastShowerScale() );
	}
	else {
	ptmax = currentTree()->incomingLines().begin()->first
	->progenitor()->momentum().mass();
	}
	}
	ptmax *= hardScaleFactor();
	// set maxHardPt for all progenitors. For partonic processes this
	// is now the max pt in the FS, for non-partonic processes or
	// processes with no coloured FS the invariant mass of the IS
	vector<ShowerProgenitorPtr>::const_iterator ckt = p.begin();
	for (; ckt != p.end(); ckt++) (*ckt)->maxHardPt(ptmax);
	}

	void QTildeShowerHandler::setupHardScales(const vector<ShowerProgenitorPtr> & p,
	XCPtr xcomb) {
	if ( hardScaleIsMuF() &&
	(!hardVetoReadOption() \|\| firstInteraction()) ) {
	Energy hardScale = ZERO;
	if(currentTree()->isHard()) {
	assert(xcomb);
	hardScale = sqrt( xcomb->lastShowerScale() );
	}
	else {
	hardScale = currentTree()->incomingLines().begin()->first
	->progenitor()->momentum().mass();
	}
	hardScale *= hardScaleFactor();
	vector<ShowerProgenitorPtr>::const_iterator ckt = p.begin();
	for (; ckt != p.end(); ckt++) (*ckt)->hardScale(hardScale);
	muPt = hardScale;
	}
	}

	void QTildeShowerHandler::showerHardProcess(ShowerTreePtr hard, XCPtr xcomb) {
	_hardme = HwMEBasePtr();
	// extract the matrix element
	tStdXCombPtr lastXC = dynamic_ptr_cast<tStdXCombPtr>(xcomb);
	if(lastXC) {
	_hardme = dynamic_ptr_cast<HwMEBasePtr>(lastXC->matrixElement());
	}
	_decayme = HwDecayerBasePtr();
	// set the current tree
	currentTree(hard);
	hardTree(HardTreePtr());
	// work out the type of event
	currentTree()->xcombPtr(dynamic_ptr_cast<StdXCombPtr>(xcomb));
	currentTree()->identifyEventType();
	checkFlags();
	// generate the showering
	doShowering(true,xcomb);
	}

	RealEmissionProcessPtr QTildeShowerHandler::hardMatrixElementCorrection(bool hard) {
	// set the initial enhancement factors for the soft correction
	_initialenhance = 1.;
	_finalenhance = 1.;
	// see if we can get the correction from the matrix element
	// or decayer
	RealEmissionProcessPtr real;
	if(hard) {
	if(_hardme&&_hardme->hasMECorrection()) {
	_hardme->initializeMECorrection(_currenttree->perturbativeProcess(),
	_initialenhance,_finalenhance);
	if(hardMEC())
	real =
	_hardme->applyHardMatrixElementCorrection(_currenttree->perturbativeProcess());
	}
	}
	else {
	if(_decayme&&_decayme->hasMECorrection()) {
	_decayme->initializeMECorrection(_currenttree->perturbativeProcess(),
	_initialenhance,_finalenhance);
	if(hardMEC())
	real = _decayme->applyHardMatrixElementCorrection(_currenttree->perturbativeProcess());
	}
	}
	return real;
	}

	ShowerParticleVector QTildeShowerHandler::createTimeLikeChildren(tShowerParticlePtr, IdList ids) {
	// Create the ShowerParticle objects for the two children of
	// the emitting particle; set the parent/child relationship
	// if same as definition create particles, otherwise create cc
	ShowerParticleVector children;
	for(unsigned int ix=0;ix<2;++ix) {
	children.push_back(new_ptr(ShowerParticle(ids[ix+1],true)));
	if(children[ix]->id()==_progenitor->id()&&!ids[ix+1]->stable())
	children[ix]->set5Momentum(Lorentz5Momentum(_progenitor->progenitor()->mass()));
	else
	children[ix]->set5Momentum(Lorentz5Momentum(ids[ix+1]->mass()));
	}
	return children;
	}

	bool QTildeShowerHandler::timeLikeShower(tShowerParticlePtr particle,
	ShowerInteraction::Type type,
	Branching fb, bool first) {
	// don't do anything if not needed
	if(_limitEmissions == 1 \|\| hardOnly() \|\|
	( _limitEmissions == 2 && _nfs != 0) \|\|
	( _limitEmissions == 4 && _nfs + _nis != 0) ) {
	if(particle->spinInfo()) particle->spinInfo()->develop();
	return false;
	}
	// too many tries
	if(_nFSR>=_maxTryFSR) {
	++_nFailedFSR;
	// too many failed events
	if(_nFailedFSR>=_maxFailFSR)
	throw Exception() << "Too many events have failed due to too many shower emissions, in\n"
	<< "QTildeShowerHandler::timeLikeShower(). Terminating run\n"
	<< Exception::runerror;
	throw Exception() << "Too many attempted emissions in QTildeShowerHandler::timeLikeShower()\n"
	<< Exception::eventerror;
	}
	// generate the emission
	ShowerParticleVector children;
	int ntry=0;
	// generate the emission
	if(!fb.kinematics)
	fb = selectTimeLikeBranching(particle,type,HardBranchingPtr());
	// no emission, return
	if(!fb.kinematics) {
	if(particle->spinInfo()) particle->spinInfo()->develop();
	return false;
	}
	Branching fc[2];
	bool setupChildren = true;
	while (ntry<50) {
	fc[0] = Branching();
	fc[1] = Branching();
	++ntry;
	assert(fb.kinematics);
	// has emitted
	// Assign the shower kinematics to the emitting particle.
	if(setupChildren) {
	++_nFSR;
	particle->showerKinematics(fb.kinematics);
	// check highest pT
	if(fb.kinematics->pT()>progenitor()->highestpT())
	progenitor()->highestpT(fb.kinematics->pT());
	// create the children
	children = createTimeLikeChildren(particle,fb.ids);
	// update the children
	particle->showerKinematics()->
	updateChildren(particle, children,fb.type,_reconOpt>=3);
	// update number of emissions
	++_nfs;
	if(_limitEmissions!=0) {
	if(children[0]->spinInfo()) children[0]->spinInfo()->develop();
	if(children[1]->spinInfo()) children[1]->spinInfo()->develop();
	if(particle->spinInfo()) particle->spinInfo()->develop();
	return true;
	}
	setupChildren = false;
	}
	// select branchings for children
	fc[0] = selectTimeLikeBranching(children[0],type,HardBranchingPtr());
	fc[1] = selectTimeLikeBranching(children[1],type,HardBranchingPtr());
	// old default
	if(_reconOpt==0) {
	// shower the first particle
	if(fc[0].kinematics) timeLikeShower(children[0],type,fc[0],false);
	if(children[0]->spinInfo()) children[0]->spinInfo()->develop();
	// shower the second particle
	if(fc[1].kinematics) timeLikeShower(children[1],type,fc[1],false);
	if(children[1]->spinInfo()) children[1]->spinInfo()->develop();
	break;
	}
	// Herwig default
	else if(_reconOpt==1) {
	// shower the first particle
	if(fc[0].kinematics) timeLikeShower(children[0],type,fc[0],false);
	if(children[0]->spinInfo()) children[0]->spinInfo()->develop();
	// shower the second particle
	if(fc[1].kinematics) timeLikeShower(children[1],type,fc[1],false);
	if(children[1]->spinInfo()) children[1]->spinInfo()->develop();
	// branching has happened
	particle->showerKinematics()->updateParent(particle, children,fb.type);
	// clean up the vetoed emission
	if(particle->virtualMass()==ZERO) {
	particle->showerKinematics(ShoKinPtr());
	for(unsigned int ix=0;ix<children.size();++ix)
	particle->abandonChild(children[ix]);
	children.clear();
	if(particle->spinInfo()) particle->spinInfo()->decayVertex(VertexPtr());
	particle->vetoEmission(fb.type,fb.kinematics->scale());
	// generate the new emission
	fb = selectTimeLikeBranching(particle,type,HardBranchingPtr());
	// no emission, return
	if(!fb.kinematics) {
	if(particle->spinInfo()) particle->spinInfo()->develop();
	return false;
	}
	setupChildren = true;
	continue;
	}
	else
	break;
	}
	// veto children
	else if(_reconOpt>=2) {
	// cut-off masses for the branching
	const vector<Energy> & virtualMasses = fb.sudakov->virtualMasses(fb.ids);
	// compute the masses of the children
	Energy masses[3];
	for(unsigned int ix=0;ix<2;++ix) {
	if(fc[ix].kinematics) {
	const vector<Energy> & vm = fc[ix].sudakov->virtualMasses(fc[ix].ids);
	Energy2 q2 =
	fc[ix].kinematics->z()(1.-fc[ix].kinematics->z())sqr(fc[ix].kinematics->scale());
	if(fc[ix].ids[0]->id()!=ParticleID::g) q2 += sqr(vm[0]);
	masses[ix+1] = sqrt(q2);
	}
	else {
	masses[ix+1] = virtualMasses[ix+1];
	}
	}
	masses[0] = fb.ids[0]->id()!=ParticleID::g ? virtualMasses[0] : ZERO;
	double z = fb.kinematics->z();
	Energy2 pt2 = z(1.-z)(z(1.-z)sqr(fb.kinematics->scale()) + sqr(masses[0]))
	- sqr(masses[1])(1.-z) - sqr(masses[2])z;
	if(pt2>=ZERO) {
	break;
	}
	else {
	// reset the scales for the children
	for(unsigned int ix=0;ix<2;++ix) {
	if(fc[ix].kinematics)
	children[ix]->vetoEmission(fc[ix].type,fc[ix].kinematics->scale());
	else
	children[ix]->vetoEmission(ShowerPartnerType::QCDColourLine,ZERO);
	children[ix]->virtualMass(ZERO);
	}
	}
	}
	};
	if(_reconOpt>=2) {
	// shower the first particle
	if(fc[0].kinematics) timeLikeShower(children[0],type,fc[0],false);
	if(children[0]->spinInfo()) children[0]->spinInfo()->develop();
	// shower the second particle
	if(fc[1].kinematics) timeLikeShower(children[1],type,fc[1],false);
	if(children[1]->spinInfo()) children[1]->spinInfo()->develop();
	// branching has happened
	particle->showerKinematics()->updateParent(particle, children,fb.type);
	}
	if(first&&!children.empty())
	particle->showerKinematics()->resetChildren(particle,children);
	if(particle->spinInfo()) particle->spinInfo()->develop();
	return true;
	}

	bool
	QTildeShowerHandler::spaceLikeShower(tShowerParticlePtr particle, PPtr beam,
	ShowerInteraction::Type type) {
	//using the pdf's associated with the ShowerHandler assures, that
	//modified pdf's are used for the secondary interactions via
	//CascadeHandler::resetPDFs(...)
	tcPDFPtr pdf;
	if(firstPDF().particle() == _beam)
	pdf = firstPDF().pdf();
	if(secondPDF().particle() == _beam)
	pdf = secondPDF().pdf();
	Energy freeze = pdfFreezingScale();
	// don't do anything if not needed
	if(_limitEmissions == 2 \|\| hardOnly() \|\|
	( _limitEmissions == 1 && _nis != 0 ) \|\|
	( _limitEmissions == 4 && _nis + _nfs != 0 ) ) {
	if(particle->spinInfo()) particle->spinInfo()->develop();
	return false;
	}
	Branching bb;
	// generate branching
	while (true) {
	bb=_splittingGenerator->chooseBackwardBranching(*particle,beam,
	_initialenhance,
	_beam,type,
	pdf,freeze);
	// return if no emission
	if(!bb.kinematics) {
	if(particle->spinInfo()) particle->spinInfo()->develop();
	return false;
	}
	// if not vetoed break
	if(!spaceLikeVetoed(bb,particle)) break;
	// otherwise reset scale and continue
	particle->vetoEmission(bb.type,bb.kinematics->scale());
	if(particle->spinInfo()) particle->spinInfo()->decayVertex(VertexPtr());
	}
	// assign the splitting function and shower kinematics
	particle->showerKinematics(bb.kinematics);
	if(bb.kinematics->pT()>progenitor()->highestpT())
	progenitor()->highestpT(bb.kinematics->pT());
	// For the time being we are considering only 1->2 branching
	// particles as in Sudakov form factor
	tcPDPtr part[2]={bb.ids[0],bb.ids[2]};
	// Now create the actual particles, make the otherChild a final state
	// particle, while the newParent is not
	ShowerParticlePtr newParent = new_ptr(ShowerParticle(part[0],false));
	ShowerParticlePtr otherChild = new_ptr(ShowerParticle(part[1],true,true));
	ShowerParticleVector theChildren;
	theChildren.push_back(particle);
	theChildren.push_back(otherChild);
	//this updates the evolution scale
	particle->showerKinematics()->
	updateParent(newParent, theChildren,bb.type);
	// update the history if needed
	_currenttree->updateInitialStateShowerProduct(_progenitor,newParent);
	_currenttree->addInitialStateBranching(particle,newParent,otherChild);
	// for the reconstruction of kinematics, parent/child
	// relationships are according to the branching process:
	// now continue the shower
	++_nis;
	bool emitted = _limitEmissions==0 ?
	spaceLikeShower(newParent,beam,type) : false;
	if(newParent->spinInfo()) newParent->spinInfo()->develop();
	// now reconstruct the momentum
	if(!emitted) {
	if(_intrinsic.find(_progenitor)==_intrinsic.end()) {
	bb.kinematics->updateLast(newParent,ZERO,ZERO);
	}
	else {
	pair<Energy,double> kt=_intrinsic[_progenitor];
	bb.kinematics->updateLast(newParent,
	kt.first*cos(kt.second),
	kt.first*sin(kt.second));
	}
	}
	particle->showerKinematics()->
	updateChildren(newParent, theChildren,bb.type,false);
	if(_limitEmissions!=0) {
	if(particle->spinInfo()) particle->spinInfo()->develop();
	return true;
	}
	// perform the shower of the final-state particle
	timeLikeShower(otherChild,type,Branching(),true);
	updateHistory(otherChild);
	if(theChildren[1]->spinInfo()) theChildren[1]->spinInfo()->develop();
	// return the emitted
	if(particle->spinInfo()) particle->spinInfo()->develop();
	return true;
	}

	void QTildeShowerHandler::showerDecay(ShowerTreePtr decay) {
	// work out the type of event
	currentTree()->xcombPtr(StdXCombPtr());
	currentTree()->identifyEventType();
	_decayme = HwDecayerBasePtr();
	_hardme = HwMEBasePtr();
	// find the decayer
	// try the normal way if possible
	tDMPtr dm = decay->incomingLines().begin()->first->original() ->decayMode();
	if(!dm) dm = decay->incomingLines().begin()->first->copy() ->decayMode();
	if(!dm) dm = decay->incomingLines().begin()->first->progenitor()->decayMode();
	// otherwise make a string and look it up
	if(!dm) {
	string tag = decay->incomingLines().begin()->first->original()->dataPtr()->name()
	+ "->";
	OrderedParticles outgoing;
	for(map<ShowerProgenitorPtr,tShowerParticlePtr>::const_iterator
	it=decay->outgoingLines().begin();it!=decay->outgoingLines().end();++it) {
	if(abs(decay->incomingLines().begin()->first->original()->id()) == ParticleID::t &&
	abs(it->first->original()->id())==ParticleID::Wplus &&
	decay->treelinks().size() == 1) {
	ShowerTreePtr Wtree = decay->treelinks().begin()->first;
	for(map<ShowerProgenitorPtr,tShowerParticlePtr>::const_iterator
	it2=Wtree->outgoingLines().begin();it2!=Wtree->outgoingLines().end();++it2) {
	outgoing.insert(it2->first->original()->dataPtr());
	}
	}
	else {
	outgoing.insert(it->first->original()->dataPtr());
	}
	}
	for(OrderedParticles::const_iterator it=outgoing.begin(); it!=outgoing.end();++it) {
	if(it!=outgoing.begin()) tag += ",";
	tag +=(**it).name();
	}
	tag += ";";
	dm = findDecayMode(tag);
	}
	if(dm) _decayme = dynamic_ptr_cast<HwDecayerBasePtr>(dm->decayer());
	// set the ShowerTree to be showered
	currentTree(decay);
	decay->applyTransforms();
	hardTree(HardTreePtr());
	// generate the showering
	doShowering(false,XCPtr());
	// if no vetos
	// force calculation of spin correlations
	SpinPtr spInfo = decay->incomingLines().begin()->first->progenitor()->spinInfo();
	if(spInfo) {
	if(!spInfo->developed()) spInfo->needsUpdate();
	spInfo->develop();
	}
	}

	bool QTildeShowerHandler::spaceLikeDecayShower(tShowerParticlePtr particle,
	const ShowerParticle::EvolutionScales & maxScales,
	Energy minmass,ShowerInteraction::Type type,
	Branching fb) {
	// too many tries
	if(_nFSR>=_maxTryFSR) {
	++_nFailedFSR;
	// too many failed events
	if(_nFailedFSR>=_maxFailFSR)
	throw Exception() << "Too many events have failed due to too many shower emissions, in\n"
	<< "QTildeShowerHandler::timeLikeShower(). Terminating run\n"
	<< Exception::runerror;
	throw Exception() << "Too many attempted emissions in QTildeShowerHandler::timeLikeShower()\n"
	<< Exception::eventerror;
	}
	// generate the emission
	ShowerParticleVector children;
	int ntry=0;
	// generate the emission
	if(!fb.kinematics)
	fb = selectSpaceLikeDecayBranching(particle,maxScales,minmass,type,
	HardBranchingPtr());
	// no emission, return
	if(!fb.kinematics) return false;
	Branching fc[2];
	bool setupChildren = true;
	while (ntry<50) {
	if(particle->virtualMass()==ZERO)
	particle->virtualMass(_progenitor->progenitor()->mass());
	fc[0] = Branching();
	fc[1] = Branching();
	++ntry;
	assert(fb.kinematics);
	// has emitted
	// Assign the shower kinematics to the emitting particle.
	if(setupChildren) {
	++_nFSR;
	// Assign the shower kinematics to the emitting particle.
	particle->showerKinematics(fb.kinematics);
	if(fb.kinematics->pT()>progenitor()->highestpT())
	progenitor()->highestpT(fb.kinematics->pT());
	// create the ShowerParticle objects for the two children
	children = createTimeLikeChildren(particle,fb.ids);
	// updateChildren the children
	particle->showerKinematics()->
	updateChildren(particle, children, fb.type,_reconOpt>=3);
	setupChildren = false;
	}
	// select branchings for children
	fc[0] = selectSpaceLikeDecayBranching(children[0],maxScales,minmass,
	type,HardBranchingPtr());
	fc[1] = selectTimeLikeBranching (children[1],type,HardBranchingPtr());
	// old default
	if(_reconOpt==0) {
	// shower the first particle
	_currenttree->updateInitialStateShowerProduct(_progenitor,children[0]);
	_currenttree->addInitialStateBranching(particle,children[0],children[1]);
	if(fc[0].kinematics) spaceLikeDecayShower(children[0],maxScales,minmass,type,Branching());
	// shower the second particle
	if(fc[1].kinematics) timeLikeShower(children[1],type,fc[1],true);
	updateHistory(children[1]);
	// branching has happened
	break;
	}
	// Herwig default
	else if(_reconOpt==1) {
	// shower the first particle
	_currenttree->updateInitialStateShowerProduct(_progenitor,children[0]);
	_currenttree->addInitialStateBranching(particle,children[0],children[1]);
	if(fc[0].kinematics) spaceLikeDecayShower(children[0],maxScales,minmass,type,Branching());
	// shower the second particle
	if(fc[1].kinematics) timeLikeShower(children[1],type,fc[1],true);
	updateHistory(children[1]);
	// branching has happened
	particle->showerKinematics()->updateParent(particle, children,fb.type);
	// clean up the vetoed emission
	if(particle->virtualMass()==ZERO) {
	particle->showerKinematics(ShoKinPtr());
	for(unsigned int ix=0;ix<children.size();++ix)
	particle->abandonChild(children[ix]);
	children.clear();
	particle->vetoEmission(fb.type,fb.kinematics->scale());
	// generate the new emission
	fb = selectSpaceLikeDecayBranching(particle,maxScales,minmass,type,
	HardBranchingPtr());
	// no emission, return
	if(!fb.kinematics) {
	return false;
	}
	setupChildren = true;
	continue;
	}
	else
	break;
	}
	else if(_reconOpt>=2) {
	// cut-off masses for the branching
	const vector<Energy> & virtualMasses = fb.sudakov->virtualMasses(fb.ids);
	// compute the masses of the children
	Energy masses[3];
	// space-like children
	masses[1] = children[0]->virtualMass();
	// time-like child
	if(fc[1].kinematics) {
	const vector<Energy> & vm = fc[1].sudakov->virtualMasses(fc[1].ids);
	Energy2 q2 =
	fc[1].kinematics->z()(1.-fc[1].kinematics->z())sqr(fc[1].kinematics->scale());
	if(fc[1].ids[0]->id()!=ParticleID::g) q2 += sqr(vm[0]);
	masses[2] = sqrt(q2);
	}
	else {
	masses[2] = virtualMasses[2];
	}
	masses[0]=particle->virtualMass();
	double z = fb.kinematics->z();
	Energy2 pt2 = (1.-z)(zsqr(masses[0])-sqr(masses[1])-z/(1.-z)*sqr(masses[2]));
	if(pt2>=ZERO) {
	break;
	}
	else {
	// reset the scales for the children
	for(unsigned int ix=0;ix<2;++ix) {
	if(fc[ix].kinematics)
	children[ix]->vetoEmission(fc[ix].type,fc[ix].kinematics->scale());
	else {
	if(ix==0)
	children[ix]->vetoEmission(ShowerPartnerType::QCDColourLine,Constants::MaxEnergy);
	else
	children[ix]->vetoEmission(ShowerPartnerType::QCDColourLine,ZERO);
	}
	}
	children[0]->virtualMass(_progenitor->progenitor()->mass());
	children[1]->virtualMass(ZERO);
	}
	}
	};
	if(_reconOpt>=2) {
	// In the case of splittings which involves coloured particles,
	// set properly the colour flow of the branching.
	// update the history if needed
	_currenttree->updateInitialStateShowerProduct(_progenitor,children[0]);
	_currenttree->addInitialStateBranching(particle,children[0],children[1]);
	// shower the first particle
	if(fc[0].kinematics) spaceLikeDecayShower(children[0],maxScales,minmass,type,Branching());
	// shower the second particle
	if(fc[1].kinematics) timeLikeShower(children[1],type,fc[1],true);
	updateHistory(children[1]);
	// branching has happened
	particle->showerKinematics()->updateParent(particle, children,fb.type);
	}
	// branching has happened
	return true;
	}

	vector<ShowerProgenitorPtr> QTildeShowerHandler::setupShower(bool hard) {
	RealEmissionProcessPtr real;
	// generate hard me if needed
	if(_hardEmission==1) {
	real = hardMatrixElementCorrection(hard);
	if(real&&!real->outgoing().empty()) setupMECorrection(real);
	}
	// generate POWHEG hard emission if needed
	else if(_hardEmission==2)
	hardestEmission(hard);
	// set the initial colour partners
	setEvolutionPartners(hard,interaction_,false);
	// get the particles to be showered
	vector<ShowerProgenitorPtr> particlesToShower =
	currentTree()->extractProgenitors();
	// return the answer
	return particlesToShower;
	}

	void QTildeShowerHandler::setEvolutionPartners(bool hard,ShowerInteraction::Type type,
	bool clear) {
	// match the particles in the ShowerTree and hardTree
	if(hardTree() && !hardTree()->connect(currentTree()))
	throw Exception() << "Can't match trees in "
	<< "QTildeShowerHandler::setEvolutionPartners()"
	<< Exception::eventerror;
	// extract the progenitors
	vector<ShowerParticlePtr> particles =
	currentTree()->extractProgenitorParticles();
	// clear the partners if needed
	if(clear) {
	for(unsigned int ix=0;ix<particles.size();++ix) {
	particles[ix]->partner(ShowerParticlePtr());
	particles[ix]->clearPartners();
	}
	}
	// sort out the colour partners
	if(hardTree()) {
	// find the partner
	for(unsigned int ix=0;ix<particles.size();++ix) {
	tShowerParticlePtr partner = hardTree()->particles()[particles[ix]]->branchingParticle()->partner();
	if(!partner) continue;
	for(map<ShowerParticlePtr,tHardBranchingPtr>::const_iterator
	it=hardTree()->particles().begin();
	it!=hardTree()->particles().end();++it) {
	if(it->second->branchingParticle()==partner) {
	particles[ix]->partner(it->first);
	break;
	}
	}
	if(!particles[ix]->partner())
	throw Exception() << "Can't match partners in "
	<< "QTildeShowerHandler::setEvolutionPartners()"
	<< Exception::eventerror;
	}
	}

	// Set the initial evolution scales
	showerModel()->partnerFinder()->
	setInitialEvolutionScales(particles,!hard,interaction_,!_hardtree);
	if(hardTree() && _hardPOWHEG) {
	bool tooHard=false;
	map<ShowerParticlePtr,tHardBranchingPtr>::const_iterator
	eit=hardTree()->particles().end();
	for(unsigned int ix=0;ix<particles.size();++ix) {
	map<ShowerParticlePtr,tHardBranchingPtr>::const_iterator
	mit = hardTree()->particles().find(particles[ix]);
	Energy hardScale(ZERO);
	ShowerPartnerType::Type type(ShowerPartnerType::Undefined);
	// final-state
	if(particles[ix]->isFinalState()) {
	if(mit!= eit && !mit->second->children().empty()) {
	hardScale = mit->second->scale();
	type = mit->second->type();
	}
	}
	// initial-state
	else {
	if(mit!= eit && mit->second->parent()) {
	hardScale = mit->second->parent()->scale();
	type = mit->second->parent()->type();
	}
	}
	if(type!=ShowerPartnerType::Undefined) {
	if(type==ShowerPartnerType::QED) {
	tooHard \|= particles[ix]->scales().QED_noAO<hardScale;
	}
	else if(type==ShowerPartnerType::QCDColourLine) {
	tooHard \|= particles[ix]->scales().QCD_c_noAO<hardScale;
	}
	else if(type==ShowerPartnerType::QCDAntiColourLine) {
	tooHard \|= particles[ix]->scales().QCD_ac_noAO<hardScale;
	}
	}
	}
	if(tooHard) convertHardTree(hard,type);
	}
	}

	void QTildeShowerHandler::updateHistory(tShowerParticlePtr particle) {
	if(!particle->children().empty()) {
	ShowerParticleVector theChildren;
	for(unsigned int ix=0;ix<particle->children().size();++ix) {
	ShowerParticlePtr part = dynamic_ptr_cast<ShowerParticlePtr>
	(particle->children()[ix]);
	theChildren.push_back(part);
	}
	// update the history if needed
	if(particle==_currenttree->getFinalStateShowerProduct(_progenitor))
	_currenttree->updateFinalStateShowerProduct(_progenitor,
	particle,theChildren);
	_currenttree->addFinalStateBranching(particle,theChildren);
	for(unsigned int ix=0;ix<theChildren.size();++ix)
	updateHistory(theChildren[ix]);
	}
	}

	bool QTildeShowerHandler::startTimeLikeShower(ShowerInteraction::Type type) {
	_nFSR = 0;
	// initialize basis vectors etc
	progenitor()->progenitor()->initializeFinalState();
	if(hardTree()) {
	map<ShowerParticlePtr,tHardBranchingPtr>::const_iterator
	eit=hardTree()->particles().end(),
	mit = hardTree()->particles().find(progenitor()->progenitor());
	if( mit != eit && !mit->second->children().empty() ) {
	bool output=truncatedTimeLikeShower(progenitor()->progenitor(),
	mit->second ,type,Branching(),true);
	if(output) updateHistory(progenitor()->progenitor());
	return output;
	}
	}
	// do the shower
	bool output = hardOnly() ? false :
	timeLikeShower(progenitor()->progenitor() ,type,Branching(),true) ;
	if(output) updateHistory(progenitor()->progenitor());
	return output;
	}

	bool QTildeShowerHandler::startSpaceLikeShower(PPtr parent, ShowerInteraction::Type type) {
	// initialise the basis vectors
	progenitor()->progenitor()->initializeInitialState(parent);
	if(hardTree()) {
	map<ShowerParticlePtr,tHardBranchingPtr>::const_iterator
	eit =hardTree()->particles().end(),
	mit = hardTree()->particles().find(progenitor()->progenitor());
	if( mit != eit && mit->second->parent() ) {
	return truncatedSpaceLikeShower( progenitor()->progenitor(),
	parent, mit->second->parent(), type );
	}
	}
	// perform the shower
	return hardOnly() ? false :
	spaceLikeShower(progenitor()->progenitor(),parent,type);
	}

	bool QTildeShowerHandler::
	startSpaceLikeDecayShower(const ShowerParticle::EvolutionScales & maxScales,
	Energy minimumMass,ShowerInteraction::Type type) {
	_nFSR = 0;
	// set up the particle basis vectors
	progenitor()->progenitor()->initializeDecay();
	if(hardTree()) {
	map<ShowerParticlePtr,tHardBranchingPtr>::const_iterator
	eit =hardTree()->particles().end(),
	mit = hardTree()->particles().find(progenitor()->progenitor());
	if( mit != eit && mit->second->parent() ) {
	HardBranchingPtr branch=mit->second;
	while(branch->parent()) branch=branch->parent();
	return truncatedSpaceLikeDecayShower(progenitor()->progenitor(),maxScales,
	minimumMass, branch ,type, Branching());
	}
	}
	// perform the shower
	return hardOnly() ? false :
	spaceLikeDecayShower(progenitor()->progenitor(),maxScales,minimumMass,type,Branching());
	}

	bool QTildeShowerHandler::timeLikeVetoed(const Branching & fb,
	ShowerParticlePtr particle) {
	// work out type of interaction
	ShowerInteraction::Type type = convertInteraction(fb.type);
	// check whether emission was harder than largest pt of hard subprocess
	if ( restrictPhasespace() && fb.kinematics->pT() > _progenitor->maxHardPt() )
	return true;
	// soft matrix element correction veto
	if( softMEC()) {
	if(_hardme && _hardme->hasMECorrection()) {
	if(_hardme->softMatrixElementVeto(_progenitor,particle,fb))
	return true;
	}
	else if(_decayme && _decayme->hasMECorrection()) {
	if(_decayme->softMatrixElementVeto(_progenitor,particle,fb))
	return true;
	}
	}
	// veto on maximum pt
	if(fb.kinematics->pT()>_progenitor->maximumpT(type)) return true;
	// general vetos
	if (fb.kinematics && !_vetoes.empty()) {
	bool vetoed=false;
	for (vector<ShowerVetoPtr>::iterator v = _vetoes.begin();
	v != _vetoes.end(); ++v) {
	bool test = (**v).vetoTimeLike(_progenitor,particle,fb);
	switch((**v).vetoType()) {
	case ShowerVeto::Emission:
	vetoed \|= test;
	break;
	case ShowerVeto::Shower:
	if(test) throw VetoShower();
	break;
	case ShowerVeto::Event:
	if(test) throw Veto();
	break;
	}
	}
	if(vetoed) return true;
	}
	if ( firstInteraction() &&
	profileScales() ) {
	double weight =
	profileScales()->
	hardScaleProfile(_progenitor->hardScale(),fb.kinematics->pT());
	if ( UseRandom::rnd() > weight )
	return true;
	}
	return false;
	}

	bool QTildeShowerHandler::spaceLikeVetoed(const Branching & bb,
	ShowerParticlePtr particle) {
	// work out type of interaction
	ShowerInteraction::Type type = convertInteraction(bb.type);
	// check whether emission was harder than largest pt of hard subprocess
	if (restrictPhasespace() && bb.kinematics->pT() > _progenitor->maxHardPt())
	return true;
	// apply the soft correction
	if( softMEC() && _hardme && _hardme->hasMECorrection() ) {
	if(_hardme->softMatrixElementVeto(_progenitor,particle,bb))
	return true;
	}
	// the more general vetos

	// check vs max pt for the shower
	if(bb.kinematics->pT()>_progenitor->maximumpT(type)) return true;

	if (!_vetoes.empty()) {
	bool vetoed=false;
	for (vector<ShowerVetoPtr>::iterator v = _vetoes.begin();
	v != _vetoes.end(); ++v) {
	bool test = (**v).vetoSpaceLike(_progenitor,particle,bb);
	switch ((**v).vetoType()) {
	case ShowerVeto::Emission:
	vetoed \|= test;
	break;
	case ShowerVeto::Shower:
	if(test) throw VetoShower();
	break;
	case ShowerVeto::Event:
	if(test) throw Veto();
	break;
	}
	}
	if (vetoed) return true;
	}
	if ( firstInteraction() &&
	profileScales() ) {
	double weight =
	profileScales()->
	hardScaleProfile(_progenitor->hardScale(),bb.kinematics->pT());
	if ( UseRandom::rnd() > weight )
	return true;
	}
	return false;
	}

	bool QTildeShowerHandler::spaceLikeDecayVetoed( const Branching & fb,
	ShowerParticlePtr particle) {
	// work out type of interaction
	ShowerInteraction::Type type = convertInteraction(fb.type);
	// apply the soft correction
	if( softMEC() && _decayme && _decayme->hasMECorrection() ) {
	if(_decayme->softMatrixElementVeto(_progenitor,particle,fb))
	return true;
	}
	// veto on hardest pt in the shower
	if(fb.kinematics->pT()> _progenitor->maximumpT(type)) return true;
	// general vetos
	if (!_vetoes.empty()) {
	bool vetoed=false;
	for (vector<ShowerVetoPtr>::iterator v = _vetoes.begin();
	v != _vetoes.end(); ++v) {
	bool test = (**v).vetoSpaceLike(_progenitor,particle,fb);
	switch((**v).vetoType()) {
	case ShowerVeto::Emission:
	vetoed \|= test;
	break;
	case ShowerVeto::Shower:
	if(test) throw VetoShower();
	break;
	case ShowerVeto::Event:
	if(test) throw Veto();
	break;
	}
	if (vetoed) return true;
	}
	}
	return false;
	}

	void QTildeShowerHandler::hardestEmission(bool hard) {
	HardTreePtr ISRTree;
	// internal POWHEG in production or decay
	if( (( _hardme && _hardme->hasPOWHEGCorrection()!=0 ) \|\|
	( _decayme && _decayme->hasPOWHEGCorrection()!=0 ) ) ) {
	RealEmissionProcessPtr real;
	unsigned int type(0);
	// production
	if(_hardme) {
	assert(hard);
	real = _hardme->generateHardest( currentTree()->perturbativeProcess(),
	interaction_);
	type = _hardme->hasPOWHEGCorrection();
	}
	// decay
	else {
	assert(!hard);
	real = _decayme->generateHardest( currentTree()->perturbativeProcess() );
	type = _decayme->hasPOWHEGCorrection();
	}
	if(real) {
	// set up ther hard tree
	if(!real->outgoing().empty()) _hardtree = new_ptr(HardTree(real));
	// set up the vetos
	currentTree()->setVetoes(real->pT(),type);
	}
	// store initial state POWHEG radiation
	if(_hardtree && _hardme && _hardme->hasPOWHEGCorrection()==1)
	ISRTree = _hardtree;
	}
	else if (hard) {
	// Get minimum pT cutoff used in shower approximation
	Energy maxpt = 1.*GeV;
	int colouredIn = 0;
	int colouredOut = 0;
	for( map< ShowerProgenitorPtr, tShowerParticlePtr >::iterator it
	= currentTree()->outgoingLines().begin();
	it != currentTree()->outgoingLines().end(); ++it ) {
	if( it->second->coloured() ) colouredOut+=1;
	}
	for( map< ShowerProgenitorPtr, ShowerParticlePtr >::iterator it
	= currentTree()->incomingLines().begin();
	it != currentTree()->incomingLines().end(); ++it ) {
	if( ! it->second->coloured() ) colouredIn+=1;
	}

	if ( currentTree()->showerApproximation() ){
	if ( currentTree()->showerApproximation()->ffPtCut() == currentTree()->showerApproximation()->fiPtCut() &&
	currentTree()->showerApproximation()->ffPtCut() == currentTree()->showerApproximation()->iiPtCut() )
	maxpt = currentTree()->showerApproximation()->ffPtCut();
	else if ( colouredIn == 2 && colouredOut == 0 )
	maxpt = currentTree()->showerApproximation()->iiPtCut();
	else if ( colouredIn == 0 && colouredOut > 1 )
	maxpt = currentTree()->showerApproximation()->ffPtCut();
	else if ( colouredIn == 2 && colouredOut == 1 )
	maxpt = min(currentTree()->showerApproximation()->iiPtCut(), currentTree()->showerApproximation()->fiPtCut());
	else if ( colouredIn == 1 && colouredOut > 1 )
	maxpt = min(currentTree()->showerApproximation()->ffPtCut(), currentTree()->showerApproximation()->fiPtCut());
	else
	maxpt = min(min(currentTree()->showerApproximation()->iiPtCut(), currentTree()->showerApproximation()->fiPtCut()),
	currentTree()->showerApproximation()->ffPtCut());
	}

	// Generate hardtree from born and real emission subprocesses
	_hardtree = generateCKKW(currentTree());

	// Find transverse momentum of hardest emission
	if (_hardtree){
	for(set<HardBranchingPtr>::iterator it=_hardtree->branchings().begin();
	it!=_hardtree->branchings().end();++it) {
	if ((it)->parent() && (it)->status()==HardBranching::Incoming)
	maxpt=(*it)->branchingParticle()->momentum().perp();
	if ((it)->children().size()==2 && (it)->status()==HardBranching::Outgoing){
	if ((*it)->branchingParticle()->id()!=21 &&
	abs((*it)->branchingParticle()->id())>5 ){
	if ((*it)->children()[0]->branchingParticle()->id()==21 \|\|
	abs((*it)->children()[0]->branchingParticle()->id())<6)
	maxpt=(*it)->children()[0]->branchingParticle()->momentum().perp();
	else if ((*it)->children()[1]->branchingParticle()->id()==21 \|\|
	abs((*it)->children()[1]->branchingParticle()->id())<6)
	maxpt=(*it)->children()[1]->branchingParticle()->momentum().perp();
	}
	else {
	if ( abs((*it)->branchingParticle()->id())<6){
	if (abs((*it)->children()[0]->branchingParticle()->id())<6)
	maxpt = (*it)->children()[1]->branchingParticle()->momentum().perp();
	else
	maxpt = (*it)->children()[0]->branchingParticle()->momentum().perp();
	}
	else maxpt = (*it)->children()[1]->branchingParticle()->momentum().perp();
	}
	}
	}
	}


	// Hardest (pt) emission should be the first powheg emission.
	maxpt=min(sqrt(lastXCombPtr()->lastShowerScale()),maxpt);

	// Set maxpt to pT of emission when showering POWHEG real-emission subprocesses
	if (!currentTree()->isPowhegSEvent() && !currentTree()->isPowhegHEvent()){
	vector<int> outGluon;
	vector<int> outQuark;
	map< ShowerProgenitorPtr, tShowerParticlePtr >::iterator it;
	for( it = currentTree()->outgoingLines().begin();
	it != currentTree()->outgoingLines().end(); ++it ) {
	if ( abs(it->second->id())< 6) outQuark.push_back(it->second->id());
	if ( it->second->id()==21 ) outGluon.push_back(it->second->id());
	}
	if (outGluon.size() + outQuark.size() == 1){
	for( it = currentTree()->outgoingLines().begin();
	it != currentTree()->outgoingLines().end(); ++it ) {
	if ( abs(it->second->id())< 6 \|\| it->second->id()==21 )
	maxpt = it->second->momentum().perp();
	}
	}
	else if (outGluon.size() + outQuark.size() > 1){
	// assume qqbar pair from a Z/gamma
	if (outGluon.size()==1 && outQuark.size() == 2 && outQuark[0]==-outQuark[1]){
	for( it = currentTree()->outgoingLines().begin();
	it != currentTree()->outgoingLines().end(); ++it ) {
	if ( it->second->id()==21 )
	maxpt = it->second->momentum().perp();
	}
	}
	// otherwise take the lowest pT avoiding born DY events
	else {
	maxpt = generator()->maximumCMEnergy();
	for( it = currentTree()->outgoingLines().begin();
	it != currentTree()->outgoingLines().end(); ++it ) {
	if ( abs(it->second->id())< 6 \|\| it->second->id()==21 )
	maxpt = min(maxpt,it->second->momentum().perp());
	}
	}
	}
	}

	// set maximum pT for subsequent emissions from S events
	if ( currentTree()->isPowhegSEvent() \|\| (!currentTree()->isPowhegSEvent() && !currentTree()->isPowhegHEvent())){
	for( map< ShowerProgenitorPtr, tShowerParticlePtr >::iterator it
	= currentTree()->outgoingLines().begin();
	it != currentTree()->outgoingLines().end(); ++it ) {
	if( ! it->second->coloured() ) continue;
	it->first->maximumpT(maxpt, ShowerInteraction::QCD );
	}
	for( map< ShowerProgenitorPtr, ShowerParticlePtr >::iterator it
	= currentTree()->incomingLines().begin();
	it != currentTree()->incomingLines().end(); ++it ) {
	if( ! it->second->coloured() ) continue;
	it->first->maximumpT(maxpt, ShowerInteraction::QCD );
	}
	}
	}
	else
	_hardtree = generateCKKW(currentTree());

	// if hard me doesn't have a FSR powheg
	// correction use decay powheg correction
	if (_hardme && _hardme->hasPOWHEGCorrection()<2) {
	addFSRUsingDecayPOWHEG(ISRTree);
	}
	// connect the trees
	if(_hardtree) {
	connectTrees(currentTree(),_hardtree,hard);
	}
	}

	void QTildeShowerHandler::addFSRUsingDecayPOWHEG(HardTreePtr ISRTree) {
	// check for intermediate colour singlet resonance
	const ParticleVector inter = _hardme->subProcess()->intermediates();
	if (inter.size()!=1 \|\| inter[0]->momentum().m2()/GeV2 < 0 \|\|
	inter[0]->dataPtr()->iColour()!=PDT::Colour0) {
	return;
	}

	// ignore cases where outgoing particles are not coloured
	map<ShowerProgenitorPtr, tShowerParticlePtr > out = currentTree()->outgoingLines();
	if (out.size() != 2 \|\|
	out. begin()->second->dataPtr()->iColour()==PDT::Colour0 \|\|
	out.rbegin()->second->dataPtr()->iColour()==PDT::Colour0) {
	return;
	}

	// look up decay mode
	tDMPtr dm;
	string tag;
	string inParticle = inter[0]->dataPtr()->name() + "->";
	vector<string> outParticles;
	outParticles.push_back(out.begin ()->first->progenitor()->dataPtr()->name());
	outParticles.push_back(out.rbegin()->first->progenitor()->dataPtr()->name());
	for (int it=0; it<2; ++it){
	tag = inParticle + outParticles[it] + "," + outParticles[(it+1)%2] + ";";
	dm = generator()->findDecayMode(tag);
	if(dm) break;
	}

	// get the decayer
	HwDecayerBasePtr decayer;
	if(dm) decayer = dynamic_ptr_cast<HwDecayerBasePtr>(dm->decayer());
	// check if decayer has a FSR POWHEG correction
	if (!decayer \|\| decayer->hasPOWHEGCorrection()<2) {
	return;
	}
	// generate the hardest emission
	// create RealEmissionProcess
	PPtr in = new_ptr(*inter[0]);
	RealEmissionProcessPtr newProcess(new_ptr(RealEmissionProcess()));
	newProcess->bornIncoming().push_back(in);
	newProcess->bornOutgoing().push_back(out.begin ()->first->progenitor());
	newProcess->bornOutgoing().push_back(out.rbegin()->first->progenitor());
	// generate the FSR
	newProcess = decayer->generateHardest(newProcess);
	HardTreePtr FSRTree;
	if(newProcess) {
	// set up ther hard tree
	if(!newProcess->outgoing().empty()) FSRTree = new_ptr(HardTree(newProcess));
	// set up the vetos
	currentTree()->setVetoes(newProcess->pT(),2);
	}
	if(!FSRTree) return;

	// if there is no ISRTree make _hardtree from FSRTree
	if (!ISRTree){
	vector<HardBranchingPtr> inBranch,hardBranch;
	for(map<ShowerProgenitorPtr,ShowerParticlePtr>::const_iterator
	cit =currentTree()->incomingLines().begin();
	cit!=currentTree()->incomingLines().end();++cit ) {
	inBranch.push_back(new_ptr(HardBranching(cit->second,SudakovPtr(),
	HardBranchingPtr(),
	HardBranching::Incoming)));
	inBranch.back()->beam(cit->first->original()->parents()[0]);
	hardBranch.push_back(inBranch.back());
	}
	if(inBranch[0]->branchingParticle()->dataPtr()->coloured()) {
	inBranch[0]->colourPartner(inBranch[1]);
	inBranch[1]->colourPartner(inBranch[0]);
	}
	for(set<HardBranchingPtr>::iterator it=FSRTree->branchings().begin();
	it!=FSRTree->branchings().end();++it) {
	if((**it).branchingParticle()->id()!=in->id())
	hardBranch.push_back(*it);
	}
	hardBranch[2]->colourPartner(hardBranch[3]);
	hardBranch[3]->colourPartner(hardBranch[2]);
	HardTreePtr newTree = new_ptr(HardTree(hardBranch,inBranch,
	ShowerInteraction::QCD));
	_hardtree = newTree;
	}

	// Otherwise modify the ISRTree to include the emission in FSRTree
	else {
	vector<tShowerParticlePtr> FSROut, ISROut;
	set<HardBranchingPtr>::iterator itFSR, itISR;
	// get outgoing particles
	for(itFSR =FSRTree->branchings().begin();
	itFSR!=FSRTree->branchings().end();++itFSR){
	if ((**itFSR).status()==HardBranching::Outgoing)
	FSROut.push_back((*itFSR)->branchingParticle());
	}
	for(itISR =ISRTree->branchings().begin();
	itISR!=ISRTree->branchings().end();++itISR){
	if ((**itISR).status()==HardBranching::Outgoing)
	ISROut.push_back((*itISR)->branchingParticle());
	}

	// find COM frame formed by outgoing particles
	LorentzRotation eventFrameFSR, eventFrameISR;
	eventFrameFSR = ((FSROut[0]->momentum()+FSROut[1]->momentum()).findBoostToCM());
	eventFrameISR = ((ISROut[0]->momentum()+ISROut[1]->momentum()).findBoostToCM());

	// find rotation between ISR and FSR frames
	int j=0;
	if (ISROut[0]->id()!=FSROut[0]->id()) j=1;
	eventFrameISR.rotateZ( (eventFrameFSR*FSROut[0]->momentum()).phi()-
	(eventFrameISR*ISROut[j]->momentum()).phi() );
	eventFrameISR.rotateY( (eventFrameFSR*FSROut[0]->momentum()).theta()-
	(eventFrameISR*ISROut[j]->momentum()).theta() );
	eventFrameISR.invert();

	for (itFSR=FSRTree->branchings().begin();
	itFSR!=FSRTree->branchings().end();++itFSR){
	if ((**itFSR).branchingParticle()->id()==in->id()) continue;
	for (itISR =ISRTree->branchings().begin();
	itISR!=ISRTree->branchings().end();++itISR){
	if ((**itISR).status()==HardBranching::Incoming) continue;
	if ((**itFSR).branchingParticle()->id()==
	(**itISR).branchingParticle()->id()){
	// rotate FSRTree particle to ISRTree event frame
	(*itISR).branchingParticle()->setMomentum(eventFrameISR
	eventFrameFSR*
	(**itFSR).branchingParticle()->momentum());
	(**itISR).branchingParticle()->rescaleMass();
	// add the children of the FSRTree particles to the ISRTree
	if(!(**itFSR).children().empty()){
	(itISR).addChild((itFSR).children()[0]);
	(itISR).addChild((itFSR).children()[1]);
	// rotate momenta to ISRTree event frame
	(*itISR).children()[0]->branchingParticle()->setMomentum(eventFrameISR
	eventFrameFSR*
	(**itFSR).children()[0]->branchingParticle()->momentum());
	(*itISR).children()[1]->branchingParticle()->setMomentum(eventFrameISR
	eventFrameFSR*
	(**itFSR).children()[1]->branchingParticle()->momentum());
	}
	}
	}
	}
	_hardtree = ISRTree;
	}
	}

	bool QTildeShowerHandler::truncatedTimeLikeShower(tShowerParticlePtr particle,
	HardBranchingPtr branch,
	ShowerInteraction::Type type,
	Branching fb, bool first) {
	// select a branching if we don't have one
	if(!fb.kinematics)
	fb = selectTimeLikeBranching(particle,type,branch);
	// must be an emission, the forced one it not a truncated one
	assert(fb.kinematics);
	ShowerParticleVector children;
	int ntry=0;
	Branching fc[2];
	bool setupChildren = true;
	while (ntry<50) {
	if(!fc[0].hard) fc[0] = Branching();
	if(!fc[1].hard) fc[1] = Branching();
	++ntry;
	// Assign the shower kinematics to the emitting particle.
	if(setupChildren) {
	++_nFSR;
	// Assign the shower kinematics to the emitting particle.
	particle->showerKinematics(fb.kinematics);
	if(fb.kinematics->pT()>progenitor()->highestpT())
	progenitor()->highestpT(fb.kinematics->pT());
	// create the children
	children = createTimeLikeChildren(particle,fb.ids);
	// update the children
	particle->showerKinematics()->
	updateChildren(particle, children,fb.type,_reconOpt>=3);
	setupChildren = false;
	}
	// select branchings for children
	if(!fc[0].kinematics) {
	// select branching for first particle
	if(!fb.hard && fb.iout ==1 )
	fc[0] = selectTimeLikeBranching(children[0],type,branch);
	else if(fb.hard && !branch->children()[0]->children().empty() )
	fc[0] = selectTimeLikeBranching(children[0],type,branch->children()[0]);
	else
	fc[0] = selectTimeLikeBranching(children[0],type,HardBranchingPtr());
	}
	// select branching for the second particle
	if(!fc[1].kinematics) {
	// select branching for first particle
	if(!fb.hard && fb.iout ==2 )
	fc[1] = selectTimeLikeBranching(children[1],type,branch);
	else if(fb.hard && !branch->children()[1]->children().empty() )
	fc[1] = selectTimeLikeBranching(children[1],type,branch->children()[1]);
	else
	fc[1] = selectTimeLikeBranching(children[1],type,HardBranchingPtr());
	}
	// old default
	if(_reconOpt==0 \|\| (_reconOpt==1 && fb.hard) ) {
	// shower the first particle
	if(fc[0].kinematics) {
	// the parent has truncated emission and following line
	if(!fb.hard && fb.iout == 1)
	truncatedTimeLikeShower(children[0],branch,type,fc[0],false);
	// hard emission and subsquent hard emissions
	else if(fb.hard && !branch->children()[0]->children().empty() )
	truncatedTimeLikeShower(children[0],branch->children()[0],type,fc[0],false);
	// normal shower
	else
	timeLikeShower(children[0],type,fc[0],false);
	}
	if(children[0]->spinInfo()) children[0]->spinInfo()->develop();
	// shower the second particle
	if(fc[1].kinematics) {
	// the parent has truncated emission and following line
	if(!fb.hard && fb.iout == 2)
	truncatedTimeLikeShower(children[1],branch,type,fc[1],false);
	// hard emission and subsquent hard emissions
	else if(fb.hard && !branch->children()[1]->children().empty() )
	truncatedTimeLikeShower(children[1],branch->children()[1],type,fc[1],false);
	else
	timeLikeShower(children[1],type,fc[1],false);
	}
	if(children[1]->spinInfo()) children[1]->spinInfo()->develop();
	// branching has happened
	particle->showerKinematics()->updateParent(particle, children,fb.type);
	break;
	}
	// H7 default
	else if(_reconOpt==1) {
	// shower the first particle
	if(fc[0].kinematics) {
	// the parent has truncated emission and following line
	if(!fb.hard && fb.iout == 1)
	truncatedTimeLikeShower(children[0],branch,type,fc[0],false);
	else
	timeLikeShower(children[0],type,fc[0],false);
	}
	if(children[0]->spinInfo()) children[0]->spinInfo()->develop();
	// shower the second particle
	if(fc[1].kinematics) {
	// the parent has truncated emission and following line
	if(!fb.hard && fb.iout == 2)
	truncatedTimeLikeShower(children[1],branch,type,fc[1],false);
	else
	timeLikeShower(children[1],type,fc[1],false);
	}
	if(children[1]->spinInfo()) children[1]->spinInfo()->develop();
	// branching has happened
	particle->showerKinematics()->updateParent(particle, children,fb.type);
	// clean up the vetoed emission
	if(particle->virtualMass()==ZERO) {
	particle->showerKinematics(ShoKinPtr());
	for(unsigned int ix=0;ix<children.size();++ix)
	particle->abandonChild(children[ix]);
	children.clear();
	if(particle->spinInfo()) particle->spinInfo()->decayVertex(VertexPtr());
	particle->vetoEmission(fb.type,fb.kinematics->scale());
	// generate the new emission
	fb = selectTimeLikeBranching(particle,type,branch);
	// must be at least hard emission
	assert(fb.kinematics);
	setupChildren = true;
	continue;
	}
	else
	break;
	}
	else if(_reconOpt>=2) {
	// cut-off masses for the branching
	const vector<Energy> & virtualMasses = fb.sudakov->virtualMasses(fb.ids);
	// compute the masses of the children
	Energy masses[3];
	for(unsigned int ix=0;ix<2;++ix) {
	if(fc[ix].kinematics) {
	const vector<Energy> & vm = fc[ix].sudakov->virtualMasses(fc[ix].ids);
	Energy2 q2 =
	fc[ix].kinematics->z()(1.-fc[ix].kinematics->z())sqr(fc[ix].kinematics->scale());
	if(fc[ix].ids[0]->id()!=ParticleID::g) q2 += sqr(vm[0]);
	masses[ix+1] = sqrt(q2);
	}
	else {
	masses[ix+1] = virtualMasses[ix+1];
	}
	}
	masses[0] = fb.ids[0]->id()!=ParticleID::g ? virtualMasses[0] : ZERO;
	double z = fb.kinematics->z();
	Energy2 pt2 = z(1.-z)(z(1.-z)sqr(fb.kinematics->scale()) + sqr(masses[0]))
	- sqr(masses[1])(1.-z) - sqr(masses[2])z;
	if(pt2>=ZERO) {
	break;
	}
	// if only the hard emission have to accept it
	else if ((fc[0].hard && !fc[1].kinematics) \|\|
	(fc[1].hard && !fc[0].kinematics) ) {
	break;
	}
	else {
	// reset the scales for the children
	for(unsigned int ix=0;ix<2;++ix) {
	if(fc[ix].hard) continue;
	if(fc[ix].kinematics && ! fc[ix].hard )
	children[ix]->vetoEmission(fc[ix].type,fc[ix].kinematics->scale());
	else
	children[ix]->vetoEmission(ShowerPartnerType::QCDColourLine,ZERO);
	children[ix]->virtualMass(ZERO);
	}
	}
	}
	};
	if(_reconOpt>=2) {
	// shower the first particle
	if(fc[0].kinematics) {
	// the parent has truncated emission and following line
	if(!fb.hard && fb.iout == 1)
	truncatedTimeLikeShower(children[0],branch,type,fc[0],false);
	// hard emission and subsquent hard emissions
	else if(fb.hard && !branch->children()[0]->children().empty() )
	truncatedTimeLikeShower(children[0],branch->children()[0],type,fc[0],false);
	// normal shower
	else
	timeLikeShower(children[0],type,fc[0],false);
	}
	if(children[0]->spinInfo()) children[0]->spinInfo()->develop();
	// shower the second particle
	if(fc[1].kinematics) {
	// the parent has truncated emission and following line
	if(!fb.hard && fb.iout == 2)
	truncatedTimeLikeShower(children[1],branch,type,fc[1],false);
	// hard emission and subsquent hard emissions
	else if(fb.hard && !branch->children()[1]->children().empty() )
	truncatedTimeLikeShower(children[1],branch->children()[1],type,fc[1],false);
	else
	timeLikeShower(children[1],type,fc[1],false);
	}
	if(children[1]->spinInfo()) children[1]->spinInfo()->develop();
	// branching has happened
	particle->showerKinematics()->updateParent(particle, children,fb.type);
	}
	if(first&&!children.empty())
	particle->showerKinematics()->resetChildren(particle,children);
	if(particle->spinInfo()) particle->spinInfo()->develop();
	return true;
	}

	bool QTildeShowerHandler::truncatedSpaceLikeShower(tShowerParticlePtr particle, PPtr beam,
	HardBranchingPtr branch,
	ShowerInteraction::Type type) {
	tcPDFPtr pdf;
	if(firstPDF().particle() == beamParticle())
	pdf = firstPDF().pdf();
	if(secondPDF().particle() == beamParticle())
	pdf = secondPDF().pdf();
	Energy freeze = pdfFreezingScale();
	Branching bb;
	// parameters of the force branching
	double z(0.);
	HardBranchingPtr timelike;
	for( unsigned int ix = 0; ix < branch->children().size(); ++ix ) {
	if( branch->children()[ix]->status() ==HardBranching::Outgoing) {
	timelike = branch->children()[ix];
	}
	if( branch->children()[ix]->status() ==HardBranching::Incoming )
	z = branch->children()[ix]->z();
	}
	// generate truncated branching
	tcPDPtr part[2];
	if(z>=0.&&z<=1.) {
	while (true) {
	if( !isTruncatedShowerON() \|\| hardOnly() ) break;
	bb = splittingGenerator()->chooseBackwardBranching( *particle,
	beam, 1., beamParticle(),
	type , pdf,freeze);
	if( !bb.kinematics \|\| bb.kinematics->scale() < branch->scale() ) {
	bb = Branching();
	break;
	}
	// particles as in Sudakov form factor
	part[0] = bb.ids[0];
	part[1] = bb.ids[2];
	double zsplit = bb.kinematics->z();
	// apply the vetos for the truncated shower
	// if doesn't carry most of momentum
	ShowerInteraction::Type type2 = convertInteraction(bb.type);
	if(type2==branch->sudakov()->interactionType() &&
	zsplit < 0.5) {
	particle->vetoEmission(bb.type,bb.kinematics->scale());
	continue;
	}
	// others
	if( part[0]->id() != particle->id() \|\| // if particle changes type
	bb.kinematics->pT() > progenitor()->maximumpT(type2) \|\| // pt veto
	bb.kinematics->scale() < branch->scale()) { // angular ordering veto
	particle->vetoEmission(bb.type,bb.kinematics->scale());
	continue;
	}
	// and those from the base class
	if(spaceLikeVetoed(bb,particle)) {
	particle->vetoEmission(bb.type,bb.kinematics->scale());
	continue;
	}
	break;
	}
	}
	if( !bb.kinematics ) {
	//do the hard emission
	ShoKinPtr kinematics =
	branch->sudakov()->createInitialStateBranching( branch->scale(), z, branch->phi(),
	branch->children()[0]->pT() );
	// assign the splitting function and shower kinematics
	particle->showerKinematics( kinematics );
	if(kinematics->pT()>progenitor()->highestpT())
	progenitor()->highestpT(kinematics->pT());
	// For the time being we are considering only 1->2 branching
	// Now create the actual particles, make the otherChild a final state
	// particle, while the newParent is not
	ShowerParticlePtr newParent =
	new_ptr( ShowerParticle( branch->branchingParticle()->dataPtr(), false ) );
	ShowerParticlePtr otherChild =
	new_ptr( ShowerParticle( timelike->branchingParticle()->dataPtr(),
	true, true ) );
	ShowerParticleVector theChildren;
	theChildren.push_back( particle );
	theChildren.push_back( otherChild );
	particle->showerKinematics()->
	updateParent( newParent, theChildren, branch->type());
	// update the history if needed
	currentTree()->updateInitialStateShowerProduct( progenitor(), newParent );
	currentTree()->addInitialStateBranching( particle, newParent, otherChild );
	// for the reconstruction of kinematics, parent/child
	// relationships are according to the branching process:
	// now continue the shower
	bool emitted=false;
	if(!hardOnly()) {
	if( branch->parent() ) {
	emitted = truncatedSpaceLikeShower( newParent, beam, branch->parent() , type);
	}
	else {
	emitted = spaceLikeShower( newParent, beam , type);
	}
	}
	if( !emitted ) {
	if( intrinsicpT().find( progenitor() ) == intrinsicpT().end() ) {
	kinematics->updateLast( newParent, ZERO, ZERO );
	}
	else {
	pair<Energy,double> kt = intrinsicpT()[progenitor()];
	kinematics->updateLast( newParent,
	kt.first*cos( kt.second ),
	kt.first*sin( kt.second ) );
	}
	}
	particle->showerKinematics()->
	updateChildren( newParent, theChildren,bb.type,false);
	if(hardOnly()) return true;
	// perform the shower of the final-state particle
	if( timelike->children().empty() ) {
	timeLikeShower( otherChild , type,Branching(),true);
	}
	else {
	truncatedTimeLikeShower( otherChild, timelike , type,Branching(), true);
	}
	updateHistory(otherChild);
	// return the emitted
	return true;
	}
	// assign the splitting function and shower kinematics
	particle->showerKinematics( bb.kinematics );
	if(bb.kinematics->pT()>progenitor()->highestpT())
	progenitor()->highestpT(bb.kinematics->pT());
	// For the time being we are considering only 1->2 branching
	// Now create the actual particles, make the otherChild a final state
	// particle, while the newParent is not
	ShowerParticlePtr newParent = new_ptr( ShowerParticle( part[0], false ) );
	ShowerParticlePtr otherChild = new_ptr( ShowerParticle( part[1], true, true ) );
	ShowerParticleVector theChildren;
	theChildren.push_back( particle );
	theChildren.push_back( otherChild );
	particle->showerKinematics()->
	updateParent( newParent, theChildren, bb.type);
	// update the history if needed
	currentTree()->updateInitialStateShowerProduct( progenitor(), newParent );
	currentTree()->addInitialStateBranching( particle, newParent, otherChild );
	// for the reconstruction of kinematics, parent/child
	// relationships are according to the branching process:
	// now continue the shower
	bool emitted = truncatedSpaceLikeShower( newParent, beam, branch,type);
	// now reconstruct the momentum
	if( !emitted ) {
	if( intrinsicpT().find( progenitor() ) == intrinsicpT().end() ) {
	bb.kinematics->updateLast( newParent, ZERO, ZERO );
	}
	else {
	pair<Energy,double> kt = intrinsicpT()[ progenitor() ];
	bb.kinematics->updateLast( newParent,
	kt.first*cos( kt.second ),
	kt.first*sin( kt.second ) );
	}
	}
	particle->showerKinematics()->
	updateChildren( newParent, theChildren, bb.type,false);
	// perform the shower of the final-state particle
	timeLikeShower( otherChild , type,Branching(),true);
	updateHistory(otherChild);
	// return the emitted
	return true;
	}

	bool QTildeShowerHandler::
	truncatedSpaceLikeDecayShower(tShowerParticlePtr particle,
	const ShowerParticle::EvolutionScales & maxScales,
	Energy minmass, HardBranchingPtr branch,
	ShowerInteraction::Type type, Branching fb) {
	// select a branching if we don't have one
	if(!fb.kinematics)
	fb = selectSpaceLikeDecayBranching(particle,maxScales,minmass,type,branch);
	// must be an emission, the forced one it not a truncated one
	assert(fb.kinematics);
	ShowerParticleVector children;
	int ntry=0;
	Branching fc[2];
	bool setupChildren = true;
	while (ntry<50) {
	if(!fc[0].hard) fc[0] = Branching();
	if(!fc[1].hard) fc[1] = Branching();
	++ntry;
	if(setupChildren) {
	++_nFSR;
	// Assign the shower kinematics to the emitting particle.
	particle->showerKinematics(fb.kinematics);
	if(fb.kinematics->pT()>progenitor()->highestpT())
	progenitor()->highestpT(fb.kinematics->pT());
	// create the ShowerParticle objects for the two children
	children = createTimeLikeChildren(particle,fb.ids);
	// updateChildren the children
	particle->showerKinematics()->
	updateChildren(particle, children, fb.type,_reconOpt>=3);
	setupChildren = false;
	}
	// select branchings for children
	if(!fc[0].kinematics) {
	if(children[0]->id()==particle->id()) {
	// select branching for first particle
	if(!fb.hard)
	fc[0] = selectSpaceLikeDecayBranching(children[0],maxScales,minmass,type,branch);
	else if(fb.hard && ! branch->children()[0]->children().empty() )
	fc[0] = selectSpaceLikeDecayBranching(children[0],maxScales,minmass,type,
	branch->children()[0]);
	else
	fc[0] = selectSpaceLikeDecayBranching(children[0],maxScales,minmass,type,
	HardBranchingPtr());
	}
	else {
	// select branching for first particle
	if(fb.hard && !branch->children()[0]->children().empty() )
	fc[0] = selectTimeLikeBranching(children[0],type,branch->children()[0]);
	else
	fc[0] = selectTimeLikeBranching(children[0],type,HardBranchingPtr());
	}
	}
	// select branching for the second particle
	if(!fc[1].kinematics) {
	if(children[1]->id()==particle->id()) {
	// select branching for first particle
	if(!fb.hard)
	fc[1] = selectSpaceLikeDecayBranching(children[1],maxScales,minmass,type,branch);
	else if(fb.hard && ! branch->children()[1]->children().empty() )
	fc[1] = selectSpaceLikeDecayBranching(children[1],maxScales,minmass,type,
	branch->children()[1]);
	else
	fc[1] = selectSpaceLikeDecayBranching(children[1],maxScales,minmass,type,
	HardBranchingPtr());
	}
	else {
	if(fb.hard && !branch->children()[1]->children().empty() )
	fc[1] = selectTimeLikeBranching(children[1],type,branch->children()[1]);
	else
	fc[1] = selectTimeLikeBranching(children[1],type,HardBranchingPtr());
	}
	}
	// old default
	if(_reconOpt==0 \|\| (_reconOpt==1 && fb.hard) ) {
	// update the history if needed
	currentTree()->updateInitialStateShowerProduct(progenitor(),children[0]);
	currentTree()->addInitialStateBranching(particle,children[0],children[1]);
	// shower the first particle
	if(fc[0].kinematics) {
	if(children[0]->id()==particle->id()) {
	if(!fb.hard)
	truncatedSpaceLikeDecayShower( children[0],maxScales,minmass,
	branch,type,fc[0]);
	else if(fb.hard && ! branch->children()[0]->children().empty() )
	truncatedSpaceLikeDecayShower( children[0],maxScales,minmass,
	branch->children()[0],type,fc[0]);
	else
	spaceLikeDecayShower( children[0],maxScales,minmass,type,fc[0]);
	}
	else {
	if(fb.hard && !branch->children()[0]->children().empty() )
	truncatedTimeLikeShower(children[0],branch->children()[0],type,fc[0],false);
	// normal shower
	else
	timeLikeShower(children[0],type,fc[0],false);
	}
	}
	// shower the second particle
	if(fc[1].kinematics) {
	if(children[0]->id()==particle->id()) {
	if(!fb.hard)
	truncatedSpaceLikeDecayShower( children[0],maxScales,minmass,
	branch,type,fc[1]);
	else if(fb.hard && ! branch->children()[0]->children().empty() )
	truncatedSpaceLikeDecayShower( children[0],maxScales,minmass,
	branch->children()[0],type,fc[1]);
	else
	spaceLikeDecayShower( children[0],maxScales,minmass,type,fc[1]);
	}
	else {
	if(fb.hard && !branch->children()[0]->children().empty() )
	truncatedTimeLikeShower(children[0],branch->children()[0],type,fc[1],false);
	// normal shower
	else
	timeLikeShower(children[0],type,fc[1],false);
	}
	}
	updateHistory(children[1]);
	// branching has happened
	break;
	}
	// H7 default
	else if(_reconOpt==1) {
	// update the history if needed
	currentTree()->updateInitialStateShowerProduct(progenitor(),children[0]);
	currentTree()->addInitialStateBranching(particle,children[0],children[1]);
	// shower the first particle
	if(fc[0].kinematics) {
	if(children[0]->id()==particle->id()) {
	if(!fb.hard)
	truncatedSpaceLikeDecayShower( children[0],maxScales,minmass,
	branch,type,fc[0]);
	else if(fb.hard && ! branch->children()[0]->children().empty() )
	truncatedSpaceLikeDecayShower( children[0],maxScales,minmass,
	branch->children()[0],type,fc[0]);
	else
	spaceLikeDecayShower( children[0],maxScales,minmass,type,fc[0]);
	}
	else {
	if(fb.hard && !branch->children()[0]->children().empty() )
	truncatedTimeLikeShower(children[0],branch->children()[0],type,fc[0],false);
	// normal shower
	else
	timeLikeShower(children[0],type,fc[0],false);
	}
	}
	// shower the second particle
	if(fc[1].kinematics) {
	if(children[0]->id()==particle->id()) {
	if(!fb.hard)
	truncatedSpaceLikeDecayShower( children[0],maxScales,minmass,
	branch,type,fc[1]);
	else if(fb.hard && ! branch->children()[0]->children().empty() )
	truncatedSpaceLikeDecayShower( children[0],maxScales,minmass,
	branch->children()[0],type,fc[1]);
	else
	spaceLikeDecayShower( children[0],maxScales,minmass,type,fc[1]);
	}
	else {
	if(fb.hard && !branch->children()[0]->children().empty() )
	truncatedTimeLikeShower(children[0],branch->children()[0],type,fc[1],false);
	// normal shower
	else
	timeLikeShower(children[0],type,fc[1],false);
	}
	}
	// clean up the vetoed emission
	if(particle->virtualMass()==ZERO) {
	particle->showerKinematics(ShoKinPtr());
	for(unsigned int ix=0;ix<children.size();++ix)
	particle->abandonChild(children[ix]);
	children.clear();
	particle->vetoEmission(fb.type,fb.kinematics->scale());
	// generate the new emission
	fb = selectSpaceLikeDecayBranching(particle,maxScales,minmass,type,branch);
	// must be at least hard emission
	assert(fb.kinematics);
	setupChildren = true;
	continue;
	}
	else {
	updateHistory(children[1]);
	break;
	}
	}
	else if(_reconOpt>=2) {
	// cut-off masses for the branching
	const vector<Energy> & virtualMasses = fb.sudakov->virtualMasses(fb.ids);
	// compute the masses of the children
	Energy masses[3];
	// space-like children
	masses[1] = children[0]->virtualMass();
	// time-like child
	if(fc[1].kinematics) {
	const vector<Energy> & vm = fc[1].sudakov->virtualMasses(fc[1].ids);
	Energy2 q2 =
	fc[1].kinematics->z()(1.-fc[1].kinematics->z())sqr(fc[1].kinematics->scale());
	if(fc[1].ids[0]->id()!=ParticleID::g) q2 += sqr(vm[0]);
	masses[2] = sqrt(q2);
	}
	else {
	masses[2] = virtualMasses[2];
	}
	masses[0]=particle->virtualMass();
	double z = fb.kinematics->z();
	Energy2 pt2 = (1.-z)(zsqr(masses[0])-sqr(masses[1])-z/(1.-z)*sqr(masses[2]));
	if(pt2>=ZERO) {
	break;
	}
	else {
	// reset the scales for the children
	for(unsigned int ix=0;ix<2;++ix) {
	if(fc[ix].kinematics)
	children[ix]->vetoEmission(fc[ix].type,fc[ix].kinematics->scale());
	else {
	if(ix==0)
	children[ix]->vetoEmission(ShowerPartnerType::QCDColourLine,Constants::MaxEnergy);
	else
	children[ix]->vetoEmission(ShowerPartnerType::QCDColourLine,ZERO);
	}
	}
	children[0]->virtualMass(_progenitor->progenitor()->mass());
	children[1]->virtualMass(ZERO);
	}
	}
	};
	if(_reconOpt>=2) {
	// update the history if needed
	currentTree()->updateInitialStateShowerProduct(progenitor(),children[0]);
	currentTree()->addInitialStateBranching(particle,children[0],children[1]);
	// shower the first particle
	if(fc[0].kinematics) {
	if(children[0]->id()==particle->id()) {
	if(!fb.hard)
	truncatedSpaceLikeDecayShower( children[0],maxScales,minmass,
	branch,type,fc[0]);
	else if(fb.hard && ! branch->children()[0]->children().empty() )
	truncatedSpaceLikeDecayShower( children[0],maxScales,minmass,
	branch->children()[0],type,fc[0]);
	else
	spaceLikeDecayShower( children[0],maxScales,minmass,type,fc[0]);
	}
	else {
	if(fb.hard && !branch->children()[0]->children().empty() )
	truncatedTimeLikeShower(children[0],branch->children()[0],type,fc[0],false);
	// normal shower
	else
	timeLikeShower(children[0],type,fc[0],false);
	}
	}
	// shower the second particle
	if(fc[1].kinematics) {
	if(children[0]->id()==particle->id()) {
	if(!fb.hard)
	truncatedSpaceLikeDecayShower( children[0],maxScales,minmass,
	branch,type,fc[1]);
	else if(fb.hard && ! branch->children()[0]->children().empty() )
	truncatedSpaceLikeDecayShower( children[0],maxScales,minmass,
	branch->children()[0],type,fc[1]);
	else
	spaceLikeDecayShower( children[0],maxScales,minmass,type,fc[1]);
	}
	else {
	if(fb.hard && !branch->children()[0]->children().empty() )
	truncatedTimeLikeShower(children[0],branch->children()[0],type,fc[1],false);
	// normal shower
	else
	timeLikeShower(children[0],type,fc[1],false);
	}
	}
	updateHistory(children[1]);
	}
	return true;
	}

	void QTildeShowerHandler::connectTrees(ShowerTreePtr showerTree,
	HardTreePtr hardTree, bool hard ) {
	ShowerParticleVector particles;
	// find the Sudakovs
	for(set<HardBranchingPtr>::iterator cit=hardTree->branchings().begin();
	cit!=hardTree->branchings().end();++cit) {
	// Sudakovs for ISR
	if((cit).parent()&&(cit).status()==HardBranching::Incoming) {
	++_nis;
	vector<long> br(3);
	br[0] = (**cit).parent()->branchingParticle()->id();
	br[1] = (**cit). branchingParticle()->id();
	br[2] = (*cit).parent()->children()[0]==cit ?
	(**cit).parent()->children()[1]->branchingParticle()->id() :
	(**cit).parent()->children()[0]->branchingParticle()->id();
	BranchingList branchings = splittingGenerator()->initialStateBranchings();
	if(br[1]<0&&br[0]==br[1]) {
	br[0] = abs(br[0]);
	br[1] = abs(br[1]);
	}
	else if(br[1]<0) {
	br[1] = -br[1];
	br[2] = -br[2];
	}
	long index = abs(br[1]);
	SudakovPtr sudakov;
	for(BranchingList::const_iterator cjt = branchings.lower_bound(index);
	cjt != branchings.upper_bound(index); ++cjt ) {
	IdList ids = cjt->second.particles;
	if(ids[0]->id()==br[0]&&ids[1]->id()==br[1]&&ids[2]->id()==br[2]) {
	sudakov=cjt->second.sudakov;
	break;
	}
	}
	if(!sudakov) throw Exception() << "Can't find Sudakov for the hard emission in "
	<< "QTildeShowerHandler::connectTrees() for ISR"
	<< Exception::runerror;
	(**cit).parent()->sudakov(sudakov);
	}
	// Sudakovs for FSR
	else if(!(**cit).children().empty()) {
	++_nfs;
	vector<long> br(3);
	br[0] = (**cit) .branchingParticle()->id();
	br[1] = (**cit).children()[0]->branchingParticle()->id();
	br[2] = (**cit).children()[1]->branchingParticle()->id();
	BranchingList branchings = splittingGenerator()->finalStateBranchings();
	if(br[0]<0) {
	br[0] = abs(br[0]);
	br[1] = abs(br[1]);
	br[2] = abs(br[2]);
	}
	long index = br[0];
	SudakovPtr sudakov;
	for(BranchingList::const_iterator cjt = branchings.lower_bound(index);
	cjt != branchings.upper_bound(index); ++cjt ) {
	IdList ids = cjt->second.particles;
	if(ids[0]->id()==br[0]&&ids[1]->id()==br[1]&&ids[2]->id()==br[2]) {
	sudakov=cjt->second.sudakov;
	break;
	}
	}
	if(!sudakov) {
	throw Exception() << "Can't find Sudakov for the hard emission in "
	<< "QTildeShowerHandler::connectTrees()"
	<< Exception::runerror;
	}
	(**cit).sudakov(sudakov);
	}
	}
	// calculate the evolution scale
	for(set<HardBranchingPtr>::iterator cit=hardTree->branchings().begin();
	cit!=hardTree->branchings().end();++cit) {
	particles.push_back((*cit)->branchingParticle());
	}
	showerModel()->partnerFinder()->
	setInitialEvolutionScales(particles,!hard,interaction_,true);
	hardTree->partnersSet(true);
	// inverse reconstruction
	if(hard) {
	showerModel()->kinematicsReconstructor()->
	deconstructHardJets(hardTree,interaction_);
	}
	else
	showerModel()->kinematicsReconstructor()->
	deconstructDecayJets(hardTree,interaction_);
	// now reset the momenta of the showering particles
	vector<ShowerProgenitorPtr> particlesToShower=showerTree->extractProgenitors();
	// match them
	map<ShowerProgenitorPtr,HardBranchingPtr> partners;
	for(set<HardBranchingPtr>::const_iterator bit=hardTree->branchings().begin();
	bit!=hardTree->branchings().end();++bit) {
	Energy2 dmin( 1e30*GeV2 );
	ShowerProgenitorPtr partner;
	for(vector<ShowerProgenitorPtr>::const_iterator pit=particlesToShower.begin();
	pit!=particlesToShower.end();++pit) {
	if(partners.find(*pit)!=partners.end()) continue;
	if( (bit).branchingParticle()->id() != (pit).progenitor()->id() ) continue;
	if( (**bit).branchingParticle()->isFinalState() !=
	(**pit).progenitor()->isFinalState() ) continue;
	if( (**pit).progenitor()->isFinalState() ) {
	Energy2 dtest =
	sqr( (pit).progenitor()->momentum().x() - (bit).showerMomentum().x() ) +
	sqr( (pit).progenitor()->momentum().y() - (bit).showerMomentum().y() ) +
	sqr( (pit).progenitor()->momentum().z() - (bit).showerMomentum().z() ) +
	sqr( (pit).progenitor()->momentum().t() - (bit).showerMomentum().t() );
	// add mass difference for identical particles (e.g. Z0 Z0 production)
	dtest += 1e10sqr((pit).progenitor()->momentum().m()-(*bit).showerMomentum().m());
	if( dtest < dmin ) {
	partner = *pit;
	dmin = dtest;
	}
	}
	else {
	// ensure directions are right
	if((pit).progenitor()->momentum().z()/(bit).showerMomentum().z()>ZERO) {
	partner = *pit;
	break;
	}
	}
	}
	if(!partner) throw Exception() << "Failed to match shower and hard trees in QTildeShowerHandler::hardestEmission"
	<< Exception::eventerror;
	partners[partner] = *bit;
	}
	for(vector<ShowerProgenitorPtr>::const_iterator pit=particlesToShower.begin();
	pit!=particlesToShower.end();++pit) {
	HardBranchingPtr partner = partners[*pit];
	if((**pit).progenitor()->dataPtr()->stable()) {
	(**pit).progenitor()->set5Momentum(partner->showerMomentum());
	(**pit).copy()->set5Momentum(partner->showerMomentum());
	}
	else {
	Lorentz5Momentum oldMomentum = (**pit).progenitor()->momentum();
	Lorentz5Momentum newMomentum = partner->showerMomentum();
	LorentzRotation boost( oldMomentum.findBoostToCM(),oldMomentum.e()/oldMomentum.mass());
	(**pit).progenitor()->transform(boost);
	(**pit).copy() ->transform(boost);
	boost = LorentzRotation(-newMomentum.findBoostToCM(),newMomentum.e()/newMomentum.mass());
	(**pit).progenitor()->transform(boost);
	(**pit).copy() ->transform(boost);
	}
	}
	// correction boosts for daughter trees
	for(map<tShowerTreePtr,pair<tShowerProgenitorPtr,tShowerParticlePtr> >::const_iterator
	tit = showerTree->treelinks().begin();
	tit != showerTree->treelinks().end();++tit) {
	ShowerTreePtr decayTree = tit->first;
	map<ShowerProgenitorPtr,ShowerParticlePtr>::const_iterator
	cit = decayTree->incomingLines().begin();
	// reset the momentum of the decay particle
	Lorentz5Momentum oldMomentum = cit->first->progenitor()->momentum();
	Lorentz5Momentum newMomentum = tit->second.second->momentum();
	LorentzRotation boost( oldMomentum.findBoostToCM(),oldMomentum.e()/oldMomentum.mass());
	decayTree->transform(boost,true);
	boost = LorentzRotation(-newMomentum.findBoostToCM(),newMomentum.e()/newMomentum.mass());
	decayTree->transform(boost,true);
	}
	}

	void QTildeShowerHandler::doShowering(bool hard,XCPtr xcomb) {
	// zero number of emissions
	_nis = _nfs = 0;
	// if MC@NLO H event and limited emissions
	// indicate both final and initial state emission
	if ( currentTree()->isMCatNLOHEvent() && _limitEmissions != 0 ) {
	_nis = _nfs = 1;
	}
	// extract particles to shower
	vector<ShowerProgenitorPtr> particlesToShower(setupShower(hard));
	// check if we should shower
	bool colCharge = false;
	for(unsigned int ix=0;ix<particlesToShower.size();++ix) {
	if(particlesToShower[ix]->progenitor()->dataPtr()->coloured() \|\|
	particlesToShower[ix]->progenitor()->dataPtr()->charged()) {
	colCharge = true;
	break;
	}
	}
	if(!colCharge) {
	_currenttree->hasShowered(true);
	return;
	}
	// setup the maximum scales for the shower
	if (restrictPhasespace()) setupMaximumScales(particlesToShower,xcomb);
	// set the hard scales for the profiles
	setupHardScales(particlesToShower,xcomb);
	// specific stuff for hard processes and decays
	Energy minmass(ZERO), mIn(ZERO);
	// hard process generate the intrinsic p_T once and for all
	if(hard) {
	generateIntrinsicpT(particlesToShower);
	}
	// decay compute the minimum mass of the final-state
	else {
	for(unsigned int ix=0;ix<particlesToShower.size();++ix) {
	if(particlesToShower[ix]->progenitor()->isFinalState()) {
	if(particlesToShower[ix]->progenitor()->dataPtr()->stable())
	minmass += particlesToShower[ix]->progenitor()->dataPtr()->constituentMass();
	else
	minmass += particlesToShower[ix]->progenitor()->mass();
	}
	else {
	mIn = particlesToShower[ix]->progenitor()->mass();
	}
	}
	// throw exception if decay can't happen
	if ( minmass > mIn ) {
	throw Exception() << "Evolver.cc: Mass of decaying particle is "
	<< "below constituent masses of decay products."
	<< Exception::eventerror;
	}
	}
	// create random particle vector (only need to do once)
	vector<ShowerProgenitorPtr> tmp;
	unsigned int nColouredIncoming = 0;
	while(particlesToShower.size()>0){
	unsigned int xx=UseRandom::irnd(particlesToShower.size());
	tmp.push_back(particlesToShower[xx]);
	particlesToShower.erase(particlesToShower.begin()+xx);
	}
	particlesToShower=tmp;
	for(unsigned int ix=0;ix<particlesToShower.size();++ix) {
	if(!particlesToShower[ix]->progenitor()->isFinalState() &&
	particlesToShower[ix]->progenitor()->coloured()) ++nColouredIncoming;
	}
	bool switchRecon = hard && nColouredIncoming !=1;
	// main shower loop
	unsigned int ntry(0);
	bool reconstructed = false;
	do {
	// clear results of last attempt if needed
	if(ntry!=0) {
	currentTree()->clear();
	setEvolutionPartners(hard,interaction_,true);
	_nis = _nfs = 0;
	// if MC@NLO H event and limited emissions
	// indicate both final and initial state emission
	if ( currentTree()->isMCatNLOHEvent() && _limitEmissions != 0 ) {
	_nis = _nfs = 1;
	}
	for(unsigned int ix=0; ix<particlesToShower.size();++ix) {
	SpinPtr spin = particlesToShower[ix]->progenitor()->spinInfo();
	if(spin && spin->decayVertex() &&
	dynamic_ptr_cast<tcSVertexPtr>(spin->decayVertex())) {
	spin->decayVertex(VertexPtr());
	}
	}
	}
	// loop over particles
	for(unsigned int ix=0;ix<particlesToShower.size();++ix) {
	// extract the progenitor
	progenitor(particlesToShower[ix]);
	// final-state radiation
	if(progenitor()->progenitor()->isFinalState()) {
	if(!doFSR()) continue;
	// perform shower
	progenitor()->hasEmitted(startTimeLikeShower(interaction_));
	}
	// initial-state radiation
	else {
	if(!doISR()) continue;
	// hard process
	if(hard) {
	// get the PDF
	setBeamParticle(_progenitor->beam());
	assert(beamParticle());
	// perform the shower
	// set the beam particle
	tPPtr beamparticle=progenitor()->original();
	if(!beamparticle->parents().empty())
	beamparticle=beamparticle->parents()[0];
	// generate the shower
	progenitor()->hasEmitted(startSpaceLikeShower(beamparticle,
	interaction_));
	}
	// decay
	else {
	// skip colour and electrically neutral particles
	if(!progenitor()->progenitor()->dataPtr()->coloured() &&
	!progenitor()->progenitor()->dataPtr()->charged()) {
	progenitor()->hasEmitted(false);
	continue;
	}
	// perform shower
	// set the scales correctly. The current scale is the maximum scale for
	// emission not the starting scale
	ShowerParticle::EvolutionScales maxScales(progenitor()->progenitor()->scales());
	progenitor()->progenitor()->scales() = ShowerParticle::EvolutionScales();
	if(progenitor()->progenitor()->dataPtr()->charged()) {
	progenitor()->progenitor()->scales().QED = progenitor()->progenitor()->mass();
	progenitor()->progenitor()->scales().QED_noAO = progenitor()->progenitor()->mass();
	}
	if(progenitor()->progenitor()->hasColour()) {
	progenitor()->progenitor()->scales().QCD_c = progenitor()->progenitor()->mass();
	progenitor()->progenitor()->scales().QCD_c_noAO = progenitor()->progenitor()->mass();
	}
	if(progenitor()->progenitor()->hasAntiColour()) {
	progenitor()->progenitor()->scales().QCD_ac = progenitor()->progenitor()->mass();
	progenitor()->progenitor()->scales().QCD_ac_noAO = progenitor()->progenitor()->mass();
	}
	// perform the shower
	progenitor()->hasEmitted(startSpaceLikeDecayShower(maxScales,minmass,
	interaction_));
	}
	}
	}
	// do the kinematic reconstruction, checking if it worked
	reconstructed = hard ?
	showerModel()->kinematicsReconstructor()->
	reconstructHardJets (currentTree(),intrinsicpT(),interaction_,
	switchRecon && ntry>maximumTries()/2) :
	showerModel()->kinematicsReconstructor()->
	reconstructDecayJets(currentTree(),interaction_);
	}
	while(!reconstructed&&maximumTries()>++ntry);
	// check if failed to generate the shower
	if(ntry==maximumTries()) {
	if(hard)
	throw ShowerHandler::ShowerTriesVeto(ntry);
	else
	throw Exception() << "Failed to generate the shower after "
	<< ntry << " attempts in QTildeShowerHandler::showerDecay()"
	<< Exception::eventerror;
	}
	// tree has now showered
	_currenttree->hasShowered(true);
	hardTree(HardTreePtr());
	}

	void QTildeShowerHandler:: convertHardTree(bool hard,ShowerInteraction::Type type) {
	map<ColinePtr,ColinePtr> cmap;
	// incoming particles
	for(map<ShowerProgenitorPtr,ShowerParticlePtr>::const_iterator
	cit=currentTree()->incomingLines().begin();cit!=currentTree()->incomingLines().end();++cit) {
	map<ShowerParticlePtr,tHardBranchingPtr>::const_iterator
	mit = hardTree()->particles().find(cit->first->progenitor());
	// put the colour lines in the map
	ShowerParticlePtr oldParticle = cit->first->progenitor();
	ShowerParticlePtr newParticle = mit->second->branchingParticle();
	ColinePtr cLine = oldParticle-> colourLine();
	ColinePtr aLine = oldParticle->antiColourLine();
	if(newParticle->colourLine() &&
	cmap.find(newParticle-> colourLine())==cmap.end())
	cmap[newParticle-> colourLine()] = cLine;
	if(newParticle->antiColourLine() &&
	cmap.find(newParticle->antiColourLine())==cmap.end())
	cmap[newParticle->antiColourLine()] = aLine;
	// check whether or not particle emits
	bool emission = mit->second->parent();
	if(emission) {
	if(newParticle->colourLine()) {
	ColinePtr ctemp = newParticle-> colourLine();
	ctemp->removeColoured(newParticle);
	}
	if(newParticle->antiColourLine()) {
	ColinePtr ctemp = newParticle->antiColourLine();
	ctemp->removeAntiColoured(newParticle);
	}
	newParticle = mit->second->parent()->branchingParticle();
	}
	// get the new colour lines
	ColinePtr newCLine,newALine;
	// sort out colour lines
	if(newParticle->colourLine()) {
	ColinePtr ctemp = newParticle-> colourLine();
	ctemp->removeColoured(newParticle);
	if(cmap.find(ctemp)!=cmap.end()) {
	newCLine = cmap[ctemp];
	}
	else {
	newCLine = new_ptr(ColourLine());
	cmap[ctemp] = newCLine;
	}
	}
	// and anticolour lines
	if(newParticle->antiColourLine()) {
	ColinePtr ctemp = newParticle->antiColourLine();
	ctemp->removeAntiColoured(newParticle);
	if(cmap.find(ctemp)!=cmap.end()) {
	newALine = cmap[ctemp];
	}
	else {
	newALine = new_ptr(ColourLine());
	cmap[ctemp] = newALine;
	}
	}
	// remove colour lines from old particle
	if(aLine) {
	aLine->removeAntiColoured(cit->first->copy());
	aLine->removeAntiColoured(cit->first->progenitor());
	}
	if(cLine) {
	cLine->removeColoured(cit->first->copy());
	cLine->removeColoured(cit->first->progenitor());
	}
	// add particle to colour lines
	if(newCLine) newCLine->addColoured (newParticle);
	if(newALine) newALine->addAntiColoured(newParticle);
	// insert new particles
	cit->first->copy(newParticle);
	ShowerParticlePtr sp(new_ptr(ShowerParticle(*newParticle,1,false)));
	cit->first->progenitor(sp);
	currentTree()->incomingLines()[cit->first]=sp;
	cit->first->perturbative(!emission);
	// and the emitted particle if needed
	if(emission) {
	ShowerParticlePtr newOut = mit->second->parent()->children()[1]->branchingParticle();
	if(newOut->colourLine()) {
	ColinePtr ctemp = newOut-> colourLine();
	ctemp->removeColoured(newOut);
	assert(cmap.find(ctemp)!=cmap.end());
	cmap[ctemp]->addColoured (newOut);
	}
	if(newOut->antiColourLine()) {
	ColinePtr ctemp = newOut->antiColourLine();
	ctemp->removeAntiColoured(newOut);
	assert(cmap.find(ctemp)!=cmap.end());
	cmap[ctemp]->addAntiColoured(newOut);
	}
	ShowerParticlePtr sout=new_ptr(ShowerParticle(*newOut,1,true));
	ShowerProgenitorPtr out=new_ptr(ShowerProgenitor(cit->first->original(),newOut,sout));
	out->perturbative(false);
	currentTree()->outgoingLines().insert(make_pair(out,sout));
	}
	if(hard) {
	// sort out the value of x
	if(mit->second->beam()->momentum().z()>ZERO) {
	sp->x(newParticle->momentum(). plus()/mit->second->beam()->momentum(). plus());
	}
	else {
	sp->x(newParticle->momentum().minus()/mit->second->beam()->momentum().minus());
	}
	}
	}
	// outgoing particles
	for(map<ShowerProgenitorPtr,tShowerParticlePtr>::const_iterator
	cit=currentTree()->outgoingLines().begin();cit!=currentTree()->outgoingLines().end();++cit) {
	map<tShowerTreePtr,pair<tShowerProgenitorPtr,
	tShowerParticlePtr> >::const_iterator tit;
	for(tit = currentTree()->treelinks().begin();
	tit != currentTree()->treelinks().end();++tit) {
	if(tit->second.first && tit->second.second==cit->first->progenitor())
	break;
	}
	map<ShowerParticlePtr,tHardBranchingPtr>::const_iterator
	mit = hardTree()->particles().find(cit->first->progenitor());
	if(mit==hardTree()->particles().end()) continue;
	// put the colour lines in the map
	ShowerParticlePtr oldParticle = cit->first->progenitor();
	ShowerParticlePtr newParticle = mit->second->branchingParticle();
	ShowerParticlePtr newOut;
	ColinePtr cLine = oldParticle-> colourLine();
	ColinePtr aLine = oldParticle->antiColourLine();
	if(newParticle->colourLine() &&
	cmap.find(newParticle-> colourLine())==cmap.end())
	cmap[newParticle-> colourLine()] = cLine;
	if(newParticle->antiColourLine() &&
	cmap.find(newParticle->antiColourLine())==cmap.end())
	cmap[newParticle->antiColourLine()] = aLine;
	// check whether or not particle emits
	bool emission = !mit->second->children().empty();
	if(emission) {
	if(newParticle->colourLine()) {
	ColinePtr ctemp = newParticle-> colourLine();
	ctemp->removeColoured(newParticle);
	}
	if(newParticle->antiColourLine()) {
	ColinePtr ctemp = newParticle->antiColourLine();
	ctemp->removeAntiColoured(newParticle);
	}
	newParticle = mit->second->children()[0]->branchingParticle();
	newOut = mit->second->children()[1]->branchingParticle();
	if(newParticle->id()!=oldParticle->id()&&newParticle->id()==newOut->id())
	swap(newParticle,newOut);
	}
	// get the new colour lines
	ColinePtr newCLine,newALine;
	// sort out colour lines
	if(newParticle->colourLine()) {
	ColinePtr ctemp = newParticle-> colourLine();
	ctemp->removeColoured(newParticle);
	if(cmap.find(ctemp)!=cmap.end()) {
	newCLine = cmap[ctemp];
	}
	else {
	newCLine = new_ptr(ColourLine());
	cmap[ctemp] = newCLine;
	}
	}
	// and anticolour lines
	if(newParticle->antiColourLine()) {
	ColinePtr ctemp = newParticle->antiColourLine();
	ctemp->removeAntiColoured(newParticle);
	if(cmap.find(ctemp)!=cmap.end()) {
	newALine = cmap[ctemp];
	}
	else {
	newALine = new_ptr(ColourLine());
	cmap[ctemp] = newALine;
	}
	}
	// remove colour lines from old particle
	if(aLine) {
	aLine->removeAntiColoured(cit->first->copy());
	aLine->removeAntiColoured(cit->first->progenitor());
	}
	if(cLine) {
	cLine->removeColoured(cit->first->copy());
	cLine->removeColoured(cit->first->progenitor());
	}
	// special for unstable particles
	if(newParticle->id()==oldParticle->id() &&
	(tit!=currentTree()->treelinks().end()\|\|!oldParticle->dataPtr()->stable())) {
	Lorentz5Momentum oldMomentum = oldParticle->momentum();
	Lorentz5Momentum newMomentum = newParticle->momentum();
	LorentzRotation boost( oldMomentum.findBoostToCM(),oldMomentum.e()/oldMomentum.mass());
	if(tit!=currentTree()->treelinks().end()) tit->first->transform(boost,false);
	oldParticle->transform(boost);
	boost = LorentzRotation(-newMomentum.findBoostToCM(),newMomentum.e()/newMomentum.mass());
	oldParticle->transform(boost);
	if(tit!=currentTree()->treelinks().end()) tit->first->transform(boost,false);
	newParticle=oldParticle;
	}
	// add particle to colour lines
	if(newCLine) newCLine->addColoured (newParticle);
	if(newALine) newALine->addAntiColoured(newParticle);
	// insert new particles
	cit->first->copy(newParticle);
	ShowerParticlePtr sp(new_ptr(ShowerParticle(*newParticle,1,true)));
	cit->first->progenitor(sp);
	currentTree()->outgoingLines()[cit->first]=sp;
	cit->first->perturbative(!emission);
	// and the emitted particle if needed
	if(emission) {
	if(newOut->colourLine()) {
	ColinePtr ctemp = newOut-> colourLine();
	ctemp->removeColoured(newOut);
	assert(cmap.find(ctemp)!=cmap.end());
	cmap[ctemp]->addColoured (newOut);
	}
	if(newOut->antiColourLine()) {
	ColinePtr ctemp = newOut->antiColourLine();
	ctemp->removeAntiColoured(newOut);
	assert(cmap.find(ctemp)!=cmap.end());
	cmap[ctemp]->addAntiColoured(newOut);
	}
	ShowerParticlePtr sout=new_ptr(ShowerParticle(*newOut,1,true));
	ShowerProgenitorPtr out=new_ptr(ShowerProgenitor(cit->first->original(),newOut,sout));
	out->perturbative(false);
	currentTree()->outgoingLines().insert(make_pair(out,sout));
	}
	// update any decay products
	if(tit!=currentTree()->treelinks().end())
	currentTree()->updateLink(tit->first,make_pair(cit->first,sp));
	}
	// reset the tree
	currentTree()->resetShowerProducts();
	// reextract the particles and set the colour partners
	vector<ShowerParticlePtr> particles =
	currentTree()->extractProgenitorParticles();
	// clear the partners
	for(unsigned int ix=0;ix<particles.size();++ix) {
	particles[ix]->partner(ShowerParticlePtr());
	particles[ix]->clearPartners();
	}
	// clear the tree
	hardTree(HardTreePtr());
	// Set the initial evolution scales
	showerModel()->partnerFinder()->
	setInitialEvolutionScales(particles,!hard,type,!_hardtree);
	}

	Branching QTildeShowerHandler::selectTimeLikeBranching(tShowerParticlePtr particle,
	ShowerInteraction::Type type,
	HardBranchingPtr branch) {
	Branching fb;
	unsigned int iout=0;
	while (true) {
	// break if doing truncated shower and no truncated shower needed
	if(branch && (!isTruncatedShowerON()\|\|hardOnly())) break;
	fb=_splittingGenerator->chooseForwardBranching(*particle,_finalenhance,type);
	// no emission break
	if(!fb.kinematics) break;
	// special for truncated shower
	if(branch) {
	// check haven't evolved too far
	if(fb.kinematics->scale() < branch->scale()) {
	fb=Branching();
	break;
	}
	// find the truncated line
	iout=0;
	if(fb.ids[1]->id()!=fb.ids[2]->id()) {
	if(fb.ids[1]->id()==particle->id()) iout=1;
	else if (fb.ids[2]->id()==particle->id()) iout=2;
	}
	else if(fb.ids[1]->id()==particle->id()) {
	if(fb.kinematics->z()>0.5) iout=1;
	else iout=2;
	}
	// apply the vetos for the truncated shower
	// no flavour changing branchings
	if(iout==0) {
	particle->vetoEmission(fb.type,fb.kinematics->scale());
	continue;
	}
	double zsplit = iout==1 ? fb.kinematics->z() : 1-fb.kinematics->z();
	// only if same interaction for forced branching
	ShowerInteraction::Type type2 = convertInteraction(fb.type);
	// and evolution
	if(type2==branch->sudakov()->interactionType()) {
	if(zsplit < 0.5 \|\| // hardest line veto
	fb.kinematics->scale()*zsplit < branch->scale() ) { // angular ordering veto
	particle->vetoEmission(fb.type,fb.kinematics->scale());
	continue;
	}
	}
	// pt veto
	if(fb.kinematics->pT() > progenitor()->maximumpT(type2)) {
	particle->vetoEmission(fb.type,fb.kinematics->scale());
	continue;
	}
	}
	// standard vetos for all emissions
	if(timeLikeVetoed(fb,particle)) {
	particle->vetoEmission(fb.type,fb.kinematics->scale());
	if(particle->spinInfo()) particle->spinInfo()->decayVertex(VertexPtr());
	continue;
	}
	// special for already decayed particles
	// don't allow flavour changing branchings
	bool vetoDecay = false;
	for(map<tShowerTreePtr,pair<tShowerProgenitorPtr,
	tShowerParticlePtr> >::const_iterator tit = currentTree()->treelinks().begin();
	tit != currentTree()->treelinks().end();++tit) {
	if(tit->second.first == progenitor()) {
	map<ShowerProgenitorPtr,tShowerParticlePtr>::const_iterator
	it = currentTree()->outgoingLines().find(progenitor());
	if(it!=currentTree()->outgoingLines().end() && particle == it->second &&
	fb.ids[0]!=fb.ids[1] && fb.ids[1]!=fb.ids[2]) {
	vetoDecay = true;
	break;
	}
	}
	}
	if(vetoDecay) {
	particle->vetoEmission(fb.type,fb.kinematics->scale());
	if(particle->spinInfo()) particle->spinInfo()->decayVertex(VertexPtr());
	continue;
	}
	break;
	}
	// normal case
	if(!branch) {
	if(fb.kinematics) fb.hard = false;
	return fb;
	}
	// truncated emission
	if(fb.kinematics) {
	fb.hard = false;
	fb.iout = iout;
	return fb;
	}
	// otherwise need to return the hard emission
	// construct the kinematics for the hard emission
	ShoKinPtr showerKin=
	branch->sudakov()->createFinalStateBranching(branch->scale(),
	branch->children()[0]->z(),
	branch->phi(),
	branch->children()[0]->pT());
	IdList idlist(3);
	idlist[0] = particle->dataPtr();
	idlist[1] = branch->children()[0]->branchingParticle()->dataPtr();
	idlist[2] = branch->children()[1]->branchingParticle()->dataPtr();
	fb = Branching( showerKin, idlist, branch->sudakov(),branch->type() );
	fb.hard = true;
	fb.iout=0;
	// return it
	return fb;
	}

	Branching QTildeShowerHandler::selectSpaceLikeDecayBranching(tShowerParticlePtr particle,
	const ShowerParticle::EvolutionScales & maxScales,
	Energy minmass,ShowerInteraction::Type type,
	HardBranchingPtr branch) {
	Branching fb;
	unsigned int iout=0;
	while (true) {
	// break if doing truncated shower and no truncated shower needed
	if(branch && (!isTruncatedShowerON()\|\|hardOnly())) break;
	// select branching
	fb=_splittingGenerator->chooseDecayBranching(*particle,maxScales,minmass,
	_initialenhance,type);
	// return if no radiation
	if(!fb.kinematics) break;
	// special for truncated shower
	if(branch) {
	// check haven't evolved too far
	if(fb.kinematics->scale() < branch->scale()) {
	fb=Branching();
	break;
	}
	// find the truncated line
	iout=0;
	if(fb.ids[1]->id()!=fb.ids[2]->id()) {
	if(fb.ids[1]->id()==particle->id()) iout=1;
	else if (fb.ids[2]->id()==particle->id()) iout=2;
	}
	else if(fb.ids[1]->id()==particle->id()) {
	if(fb.kinematics->z()>0.5) iout=1;
	else iout=2;
	}
	// apply the vetos for the truncated shower
	// no flavour changing branchings
	if(iout==0) {
	particle->vetoEmission(fb.type,fb.kinematics->scale());
	continue;
	}
	ShowerInteraction::Type type2 = convertInteraction(fb.type);
	double zsplit = iout==1 ? fb.kinematics->z() : 1-fb.kinematics->z();
	if(type2==branch->sudakov()->interactionType()) {
	if(zsplit < 0.5 \|\| // hardest line veto
	fb.kinematics->scale()*zsplit < branch->scale() ) { // angular ordering veto
	particle->vetoEmission(fb.type,fb.kinematics->scale());
	continue;
	}
	}
	// pt veto
	if(fb.kinematics->pT() > progenitor()->maximumpT(type2)) {
	particle->vetoEmission(fb.type,fb.kinematics->scale());
	continue;
	}
	}
	// if not vetoed break
	if(spaceLikeDecayVetoed(fb,particle)) {
	// otherwise reset scale and continue
	particle->vetoEmission(fb.type,fb.kinematics->scale());
	continue;
	}
	break;
	}
	// normal case
	if(!branch) {
	if(fb.kinematics) fb.hard = false;
	return fb;
	}
	// truncated emission
	if(fb.kinematics) {
	fb.hard = false;
	fb.iout = iout;
	return fb;
	}
	// otherwise need to return the hard emission
	// construct the kinematics for the hard emission
	ShoKinPtr showerKin=
	branch->sudakov()->createDecayBranching(branch->scale(),
	branch->children()[0]->z(),
	branch->phi(),
	branch->children()[0]->pT());
	IdList idlist(3);
	idlist[0] = particle->dataPtr();
	idlist[1] = branch->children()[0]->branchingParticle()->dataPtr();
	idlist[2] = branch->children()[1]->branchingParticle()->dataPtr();
	// create the branching
	fb = Branching( showerKin, idlist, branch->sudakov(),ShowerPartnerType::QCDColourLine );
	fb.hard=true;
	fb.iout=0;
	// return it
	return fb;
	}

	void QTildeShowerHandler::checkFlags() {
	string error = "Inconsistent hard emission set-up in QTildeShowerHandler::showerHardProcess(). ";
	if ( ( currentTree()->isMCatNLOSEvent() \|\| currentTree()->isMCatNLOHEvent() ) ) {
	if (_hardEmission ==2 )
	throw Exception() << error
	<< "Cannot generate POWHEG matching with MC@NLO shower "
	<< "approximation. Add 'set Evolver:HardEmission 0' to input file."
	<< Exception::runerror;
	if ( canHandleMatchboxTrunc() )
	throw Exception() << error
	<< "Cannot use truncated qtilde shower with MC@NLO shower "
	<< "approximation. Set LHCGenerator:EventHandler"
	<< ":CascadeHandler to '/Herwig/Shower/ShowerHandler' or "
	<< "'/Herwig/Shower/Dipole/DipoleShowerHandler'."
	<< Exception::runerror;
	}
	else if ( ((currentTree()->isPowhegSEvent() \|\| currentTree()->isPowhegHEvent()) ) &&
	_hardEmission != 2){
	if ( canHandleMatchboxTrunc())
	throw Exception() << error
	<< "Unmatched events requested for POWHEG shower "
	<< "approximation. Set Evolver:HardEmission to "
	<< "'POWHEG'."
	<< Exception::runerror;
	else if (_hardEmissionWarn) {
	_hardEmissionWarn = false;
	_hardEmission=2;
	throw Exception() << error
	<< "Unmatched events requested for POWHEG shower "
	<< "approximation. Changing Evolver:HardEmission from "
	<< _hardEmission << " to 2"
	<< Exception::warning;
	}
	}

	if ( currentTree()->isPowhegSEvent() \|\| currentTree()->isPowhegHEvent()) {
	if (currentTree()->showerApproximation()->needsTruncatedShower() &&
	!canHandleMatchboxTrunc() )
	throw Exception() << error
	<< "Current shower handler cannot generate truncated shower. "
	<< "Set Generator:EventHandler:CascadeHandler to "
	<< "'/Herwig/Shower/PowhegShowerHandler'."
	<< Exception::runerror;
	}
	else if ( currentTree()->truncatedShower() && _missingTruncWarn) {
	_missingTruncWarn=false;
	throw Exception() << "Warning: POWHEG shower approximation used without "
	<< "truncated shower. Set Generator:EventHandler:"
	<< "CascadeHandler to '/Herwig/Shower/PowhegShowerHandler' and "
	<< "'MEMatching:TruncatedShower Yes'."
	<< Exception::warning;
	}
	// else if ( !dipme && _hardEmissionMode > 1 &&
	// firstInteraction())
	// throw Exception() << error
	// << "POWHEG matching requested for LO events. Include "
	// << "'set Factory:ShowerApproximation MEMatching' in input file."
	// << Exception::runerror;
	}


	tPPair QTildeShowerHandler::remakeRemnant(tPPair oldp){
	// get the parton extractor
	PartonExtractor & pex = *lastExtractor();
	// get the new partons
	tPPair newp = make_pair(findFirstParton(oldp.first ),
	findFirstParton(oldp.second));
	// if the same do nothing
	if(newp == oldp) return oldp;
	// Creates the new remnants and returns the new PartonBinInstances
	// ATTENTION Broken here for very strange configuration
	PBIPair newbins = pex.newRemnants(oldp, newp, newStep());
	newStep()->addIntermediate(newp.first);
	newStep()->addIntermediate(newp.second);
	// return the new partons
	return newp;
	}

	PPtr QTildeShowerHandler::findFirstParton(tPPtr seed) const{
	if(seed->parents().empty()) return seed;
	tPPtr parent = seed->parents()[0];
	//if no parent there this is a loose end which will
	//be connected to the remnant soon.
	if(!parent \|\| parent == incomingBeams().first \|\|
	parent == incomingBeams().second ) return seed;
	else return findFirstParton(parent);
	}

	void QTildeShowerHandler::decay(ShowerTreePtr tree, ShowerDecayMap & decay) {
	// must be one incoming particle
	assert(tree->incomingLines().size()==1);
	// apply any transforms
	tree->applyTransforms();
	// if already decayed return
	if(!tree->outgoingLines().empty()) return;
	// now we need to replace the particle with a new copy after the shower
	// find particle after the shower
	map<tShowerTreePtr,pair<tShowerProgenitorPtr,tShowerParticlePtr> >::const_iterator
	tit = tree->parent()->treelinks().find(tree);
	assert(tit!=tree->parent()->treelinks().end());
	ShowerParticlePtr newparent=tit->second.second;
	PerturbativeProcessPtr newProcess = new_ptr(PerturbativeProcess());
	newProcess->incoming().push_back(make_pair(newparent,PerturbativeProcessPtr()));
	DecayProcessMap decayMap;
	ShowerHandler::decay(newProcess,decayMap);
	ShowerTree::constructTrees(tree,decay,newProcess,decayMap);
	}

	namespace {

	ShowerProgenitorPtr
	findFinalStateLine(ShowerTreePtr tree, long id, Lorentz5Momentum momentum) {
	map<ShowerProgenitorPtr,tShowerParticlePtr>::iterator partner;
	Energy2 dmin(1e30*GeV2);
	for(map<ShowerProgenitorPtr,tShowerParticlePtr>::iterator
	cit =tree->outgoingLines().begin(); cit!=tree->outgoingLines().end(); ++cit) {
	if(cit->second->id()!=id) continue;
	Energy2 test =
	sqr(cit->second->momentum().x()-momentum.x())+
	sqr(cit->second->momentum().y()-momentum.y())+
	sqr(cit->second->momentum().z()-momentum.z())+
	sqr(cit->second->momentum().t()-momentum.t());
	if(test<dmin) {
	dmin = test;
	partner = cit;
	}
	}
	return partner->first;
	}

	ShowerProgenitorPtr
	findInitialStateLine(ShowerTreePtr tree, long id, Lorentz5Momentum momentum) {
	map<ShowerProgenitorPtr,ShowerParticlePtr>::iterator partner;
	Energy2 dmin(1e30*GeV2);
	for(map<ShowerProgenitorPtr,ShowerParticlePtr>::iterator
	cit =tree->incomingLines().begin(); cit!=tree->incomingLines().end(); ++cit) {
	if(cit->second->id()!=id) continue;
	Energy2 test =
	sqr(cit->second->momentum().x()-momentum.x())+
	sqr(cit->second->momentum().y()-momentum.y())+
	sqr(cit->second->momentum().z()-momentum.z())+
	sqr(cit->second->momentum().t()-momentum.t());
	if(test<dmin) {
	dmin = test;
	partner = cit;
	}
	}
	return partner->first;
	}

	void fixSpectatorColours(PPtr newSpect,ShowerProgenitorPtr oldSpect,
	ColinePair & cline,ColinePair & aline, bool reconnect) {
	cline.first = oldSpect->progenitor()->colourLine();
	cline.second = newSpect->colourLine();
	aline.first = oldSpect->progenitor()->antiColourLine();
	aline.second = newSpect->antiColourLine();
	if(!reconnect) return;
	if(cline.first) {
	cline.first ->removeColoured(oldSpect->copy());
	cline.first ->removeColoured(oldSpect->progenitor());
	cline.second->removeColoured(newSpect);
	cline.first ->addColoured(newSpect);
	}
	if(aline.first) {
	aline.first ->removeAntiColoured(oldSpect->copy());
	aline.first ->removeAntiColoured(oldSpect->progenitor());
	aline.second->removeAntiColoured(newSpect);
	aline.first ->addAntiColoured(newSpect);
	}
	}

	void fixInitialStateEmitter(ShowerTreePtr tree, PPtr newEmit,PPtr emitted, ShowerProgenitorPtr emitter,
	ColinePair cline,ColinePair aline,double x) {
	// sort out the colours
	if(emitted->dataPtr()->iColour()==PDT::Colour8) {
	// emitter
	if(cline.first && cline.first == emitter->progenitor()->antiColourLine() &&
	cline.second !=newEmit->antiColourLine()) {
	// sort out not radiating line
	ColinePtr col = emitter->progenitor()->colourLine();
	if(col) {
	col->removeColoured(emitter->copy());
	col->removeColoured(emitter->progenitor());
	newEmit->colourLine()->removeColoured(newEmit);
	col->addColoured(newEmit);
	}
	}
	else if(aline.first && aline.first == emitter->progenitor()->colourLine() &&
	aline.second !=newEmit->colourLine()) {
	// sort out not radiating line
	ColinePtr anti = emitter->progenitor()->antiColourLine();
	if(anti) {
	anti->removeAntiColoured(emitter->copy());
	anti->removeAntiColoured(emitter->progenitor());
	newEmit->colourLine()->removeAntiColoured(newEmit);
	anti->addAntiColoured(newEmit);
	}
	}
	else
	assert(false);
	// emitted
	if(cline.first && cline.second==emitted->colourLine()) {
	cline.second->removeColoured(emitted);
	cline.first->addColoured(emitted);
	}
	else if(aline.first && aline.second==emitted->antiColourLine()) {
	aline.second->removeAntiColoured(emitted);
	aline.first->addAntiColoured(emitted);
	}
	else
	assert(false);
	}
	else {
	if(emitter->progenitor()->antiColourLine() ) {
	ColinePtr col = emitter->progenitor()->antiColourLine();
	col->removeAntiColoured(emitter->copy());
	col->removeAntiColoured(emitter->progenitor());
	if(newEmit->antiColourLine()) {
	newEmit->antiColourLine()->removeAntiColoured(newEmit);
	col->addAntiColoured(newEmit);
	}
	else if (emitted->colourLine()) {
	emitted->colourLine()->removeColoured(emitted);
	col->addColoured(emitted);
	}
	else
	assert(false);
	}
	if(emitter->progenitor()->colourLine() ) {
	ColinePtr col = emitter->progenitor()->colourLine();
	col->removeColoured(emitter->copy());
	col->removeColoured(emitter->progenitor());
	if(newEmit->colourLine()) {
	newEmit->colourLine()->removeColoured(newEmit);
	col->addColoured(newEmit);
	}
	else if (emitted->antiColourLine()) {
	emitted->antiColourLine()->removeAntiColoured(emitted);
	col->addAntiColoured(emitted);
	}
	else
	assert(false);
	}
	}
	// update the emitter
	emitter->copy(newEmit);
	ShowerParticlePtr sp = new_ptr(ShowerParticle(*newEmit,1,false));
	sp->x(x);
	emitter->progenitor(sp);
	tree->incomingLines()[emitter]=sp;
	emitter->perturbative(false);
	// add emitted
	sp=new_ptr(ShowerParticle(*emitted,1,true));
	ShowerProgenitorPtr gluon=new_ptr(ShowerProgenitor(emitter->original(),emitted,sp));
	gluon->perturbative(false);
	tree->outgoingLines().insert(make_pair(gluon,sp));
	}

	void fixFinalStateEmitter(ShowerTreePtr tree, PPtr newEmit,PPtr emitted, ShowerProgenitorPtr emitter,
	ColinePair cline,ColinePair aline) {
	map<tShowerTreePtr,pair<tShowerProgenitorPtr,tShowerParticlePtr> >::const_iterator tit;
	// special case if decayed
	for(tit = tree->treelinks().begin(); tit != tree->treelinks().end();++tit) {
	if(tit->second.first && tit->second.second==emitter->progenitor())
	break;
	}
	// sort out the colour lines
	if(cline.first && cline.first == emitter->progenitor()->antiColourLine() &&
	cline.second !=newEmit->antiColourLine()) {
	// sort out not radiating line
	ColinePtr col = emitter->progenitor()->colourLine();
	if(col) {
	col->removeColoured(emitter->copy());
	col->removeColoured(emitter->progenitor());
	newEmit->colourLine()->removeColoured(newEmit);
	col->addColoured(newEmit);
	}
	}
	else if(aline.first && aline.first == emitter->progenitor()->colourLine() &&
	aline.second !=newEmit->colourLine()) {
	// sort out not radiating line
	ColinePtr anti = emitter->progenitor()->antiColourLine();
	if(anti) {
	anti->removeAntiColoured(emitter->copy());
	anti->removeAntiColoured(emitter->progenitor());
	newEmit->colourLine()->removeAntiColoured(newEmit);
	anti->addAntiColoured(newEmit);
	}
	}
	else
	assert(false);
	// update the emitter
	emitter->copy(newEmit);
	ShowerParticlePtr sp = new_ptr(ShowerParticle(*newEmit,1,true));
	emitter->progenitor(sp);
	tree->outgoingLines()[emitter]=sp;
	emitter->perturbative(false);
	// update for decaying particles
	if(tit!=tree->treelinks().end())
	tree->updateLink(tit->first,make_pair(emitter,sp));
	// add the emitted particle
	// sort out the colour
	if(cline.first && cline.second==emitted->antiColourLine()) {
	cline.second->removeAntiColoured(emitted);
	cline.first->addAntiColoured(emitted);
	}
	else if(aline.first && aline.second==emitted->colourLine()) {
	aline.second->removeColoured(emitted);
	aline.first->addColoured(emitted);
	}
	else
	assert(false);
	sp=new_ptr(ShowerParticle(*emitted,1,true));
	ShowerProgenitorPtr gluon=new_ptr(ShowerProgenitor(emitter->original(),
	emitted,sp));
	gluon->perturbative(false);
	tree->outgoingLines().insert(make_pair(gluon,sp));
	}

	}

	void QTildeShowerHandler::setupMECorrection(RealEmissionProcessPtr real) {
	assert(real);
	currentTree()->hardMatrixElementCorrection(true);
	// II emission
	if(real->emitter() < real->incoming().size() &&
	real->spectator() < real->incoming().size()) {
	// recoiling system
	for( map<ShowerProgenitorPtr,tShowerParticlePtr>::const_iterator
	cjt= currentTree()->outgoingLines().begin();
	cjt != currentTree()->outgoingLines().end();++cjt ) {
	cjt->first->progenitor()->transform(real->transformation());
	cjt->first->copy()->transform(real->transformation());
	}
	// the the radiating system
	ShowerProgenitorPtr emitter,spectator;
	unsigned int iemit = real->emitter();
	unsigned int ispect = real->spectator();
	int ig = int(real->emitted())-int(real->incoming().size());
	emitter = findInitialStateLine(currentTree(),
	real->bornIncoming()[iemit]->id(),
	real->bornIncoming()[iemit]->momentum());
	spectator = findInitialStateLine(currentTree(),
	real->bornIncoming()[ispect]->id(),
	real->bornIncoming()[ispect]->momentum());
	// sort out the colours
	ColinePair cline,aline;
	fixSpectatorColours(real->incoming()[ispect],spectator,cline,aline,true);
	// update the spectator
	spectator->copy(real->incoming()[ispect]);
	ShowerParticlePtr sp(new_ptr(ShowerParticle(*real->incoming()[ispect],1,false)));
	sp->x(ispect ==0 ? real->x().first :real->x().second);
	spectator->progenitor(sp);
	currentTree()->incomingLines()[spectator]=sp;
	spectator->perturbative(true);
	// now for the emitter
	fixInitialStateEmitter(currentTree(),real->incoming()[iemit],real->outgoing()[ig],
	emitter,cline,aline,iemit ==0 ? real->x().first :real->x().second);
	}
	// FF emission
	else if(real->emitter() >= real->incoming().size() &&
	real->spectator() >= real->incoming().size()) {
	assert(real->outgoing()[real->emitted()-real->incoming().size()]->id()==ParticleID::g);
	// find the emitter and spectator in the shower tree
	ShowerProgenitorPtr emitter,spectator;
	int iemit = int(real->emitter())-int(real->incoming().size());
	emitter = findFinalStateLine(currentTree(),
	real->bornOutgoing()[iemit]->id(),
	real->bornOutgoing()[iemit]->momentum());
	int ispect = int(real->spectator())-int(real->incoming().size());
	spectator = findFinalStateLine(currentTree(),
	real->bornOutgoing()[ispect]->id(),
	real->bornOutgoing()[ispect]->momentum());
	map<tShowerTreePtr,pair<tShowerProgenitorPtr,tShowerParticlePtr> >::const_iterator tit;
	// first the spectator
	// special case if decayed
	for(tit = currentTree()->treelinks().begin(); tit != currentTree()->treelinks().end();++tit) {
	if(tit->second.first && tit->second.second==spectator->progenitor())
	break;
	}
	// sort out the colours
	ColinePair cline,aline;
	fixSpectatorColours(real->outgoing()[ispect],spectator,cline,aline,true);
	// update the spectator
	spectator->copy(real->outgoing()[ispect]);
	ShowerParticlePtr sp(new_ptr(ShowerParticle(*real->outgoing()[ispect],1,true)));
	spectator->progenitor(sp);
	currentTree()->outgoingLines()[spectator]=sp;
	spectator->perturbative(true);
	// update for decaying particles
	if(tit!=currentTree()->treelinks().end())
	currentTree()->updateLink(tit->first,make_pair(spectator,sp));
	// now the emitting particle
	int ig = int(real->emitted())-int(real->incoming().size());
	fixFinalStateEmitter(currentTree(),real->outgoing()[iemit],
	real->outgoing()[ig],
	emitter,cline,aline);
	}
	// IF emission
	else {
	// scattering process
	if(real->incoming().size()==2) {
	ShowerProgenitorPtr emitter,spectator;
	unsigned int iemit = real->emitter();
	unsigned int ispect = real->spectator();
	int ig = int(real->emitted())-int(real->incoming().size());
	ColinePair cline,aline;
	// incoming spectator
	if(ispect<2) {
	spectator = findInitialStateLine(currentTree(),
	real->bornIncoming()[ispect]->id(),
	real->bornIncoming()[ispect]->momentum());
	fixSpectatorColours(real->incoming()[ispect],spectator,cline,aline,true);
	// update the spectator
	spectator->copy(real->incoming()[ispect]);
	ShowerParticlePtr sp(new_ptr(ShowerParticle(*real->incoming()[ispect],1,false)));
	sp->x(ispect ==0 ? real->x().first :real->x().second);
	spectator->progenitor(sp);
	currentTree()->incomingLines()[spectator]=sp;
	spectator->perturbative(true);
	}
	// outgoing spectator
	else {
	spectator = findFinalStateLine(currentTree(),
	real->bornOutgoing()[ispect-real->incoming().size()]->id(),
	real->bornOutgoing()[ispect-real->incoming().size()]->momentum());
	// special case if decayed
	map<tShowerTreePtr,pair<tShowerProgenitorPtr,tShowerParticlePtr> >::const_iterator tit;
	for(tit = currentTree()->treelinks().begin(); tit != currentTree()->treelinks().end();++tit) {
	if(tit->second.first && tit->second.second==spectator->progenitor())
	break;
	}
	fixSpectatorColours(real->outgoing()[ispect-real->incoming().size()],spectator,cline,aline,true);
	// update the spectator
	spectator->copy(real->outgoing()[ispect-real->incoming().size()]);
	ShowerParticlePtr sp(new_ptr(ShowerParticle(*real->outgoing()[ispect-real->incoming().size()],1,true)));
	spectator->progenitor(sp);
	currentTree()->outgoingLines()[spectator]=sp;
	spectator->perturbative(true);
	// update for decaying particles
	if(tit!=currentTree()->treelinks().end())
	currentTree()->updateLink(tit->first,make_pair(spectator,sp));
	}
	// incoming emitter
	if(iemit<2) {
	emitter = findInitialStateLine(currentTree(),
	real->bornIncoming()[iemit]->id(),
	real->bornIncoming()[iemit]->momentum());
	fixInitialStateEmitter(currentTree(),real->incoming()[iemit],real->outgoing()[ig],
	emitter,aline,cline,iemit ==0 ? real->x().first :real->x().second);
	}
	// outgoing emitter
	else {
	emitter = findFinalStateLine(currentTree(),
	real->bornOutgoing()[iemit-real->incoming().size()]->id(),
	real->bornOutgoing()[iemit-real->incoming().size()]->momentum());
	fixFinalStateEmitter(currentTree(),real->outgoing()[iemit-real->incoming().size()],
	real->outgoing()[ig],emitter,aline,cline);
	}
	}
	// decay process
	else {
	assert(real->spectator()==0);
	unsigned int iemit = real->emitter()-real->incoming().size();
	int ig = int(real->emitted())-int(real->incoming().size());
	ColinePair cline,aline;
	// incoming spectator
	ShowerProgenitorPtr spectator = findInitialStateLine(currentTree(),
	real->bornIncoming()[0]->id(),
	real->bornIncoming()[0]->momentum());
	fixSpectatorColours(real->incoming()[0],spectator,cline,aline,false);
	// find the emitter
	ShowerProgenitorPtr emitter =
	findFinalStateLine(currentTree(),
	real->bornOutgoing()[iemit]->id(),
	real->bornOutgoing()[iemit]->momentum());
	// recoiling system
	for( map<ShowerProgenitorPtr,tShowerParticlePtr>::const_iterator
	cjt= currentTree()->outgoingLines().begin();
	cjt != currentTree()->outgoingLines().end();++cjt ) {
	if(cjt->first==emitter) continue;
	cjt->first->progenitor()->transform(real->transformation());
	cjt->first->copy()->transform(real->transformation());
	}
	// sort out the emitter
	fixFinalStateEmitter(currentTree(),real->outgoing()[iemit],
	real->outgoing()[ig],emitter,aline,cline);
	}
	}
	// clean up the shower tree
	_currenttree->resetShowerProducts();
	}

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