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	diff --git a/Hadronization/ClusterFissioner.cc b/Hadronization/ClusterFissioner.cc
	--- a/Hadronization/ClusterFissioner.cc
	+++ b/Hadronization/ClusterFissioner.cc
	@@ -1,1136 +1,1169 @@
	// -- C++ --
	//
	// ClusterFissioner.cc is a part of Herwig - A multi-purpose Monte Carlo event generator
	// Copyright (C) 2002-2019 The Herwig Collaboration
	//
	// Herwig is licenced under version 3 of the GPL, see COPYING for details.
	// Please respect the MCnet academic guidelines, see GUIDELINES for details.
	//
	//
	// Thisk is the implementation of the non-inlined, non-templated member
	// functions of the ClusterFissioner class.
	//

	#include "ClusterFissioner.h"
	#include <ThePEG/Interface/ClassDocumentation.h>
	#include <ThePEG/Interface/Reference.h>
	#include <ThePEG/Interface/Parameter.h>
	#include <ThePEG/Interface/Switch.h>
	#include <ThePEG/Persistency/PersistentOStream.h>
	#include <ThePEG/Persistency/PersistentIStream.h>
	#include <ThePEG/PDT/EnumParticles.h>
	#include "Herwig/Utilities/Kinematics.h"
	#include "Cluster.h"
	#include "ThePEG/Repository/UseRandom.h"
	#include "ThePEG/Repository/EventGenerator.h"
	#include <ThePEG/Utilities/DescribeClass.h>
	#include "ThePEG/Interface/ParMap.h"

	using namespace Herwig;

	DescribeClass<ClusterFissioner,Interfaced>
	describeClusterFissioner("Herwig::ClusterFissioner","Herwig.so");

	ClusterFissioner::ClusterFissioner() :
	_clMaxLight(3.35*GeV),
	_clMaxExotic(3.35*GeV),
	_clPowLight(2.0),
	_clPowExotic(2.0),
	_pSplitLight(1.0),
	_pSplitExotic(1.0),
	+ _phaseSpaceWeights(false),
	+ _dim(4),
	_fissionCluster(0),
	_kinematicThresholdChoice(0),
	_btClM(1.0*GeV),
	_iopRem(1),
	_kappa(1.0e15*GeV/meter),
	_enhanceSProb(0),
	_m0Fission(2.*GeV),
	_massMeasure(0),
	_probPowFactor(4.0),
	_probShift(0.0),
	_kinThresholdShift(1.0*sqr(GeV))
	{}

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

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

	void ClusterFissioner::persistentOutput(PersistentOStream & os) const {
	os << ounit(_clMaxLight,GeV)
	<< ounit(_clMaxHeavy,GeV) << ounit(_clMaxExotic,GeV) << _clPowLight << _clPowHeavy
	<< _clPowExotic << _pSplitLight
	<< _pSplitHeavy << _pSplitExotic
	<< _fissionCluster << _fissionPwt
	<< ounit(_btClM,GeV)
	<< _iopRem << ounit(_kappa, GeV/meter)
	- << _enhanceSProb << ounit(_m0Fission,GeV) << _massMeasure
	+ << _enhanceSProb << ounit(_m0Fission,GeV) << _massMeasure << _dim << _phaseSpaceWeights
	<< _hadronSpectrum
	<< _probPowFactor << _probShift << ounit(_kinThresholdShift,sqr(GeV));
	}

	void ClusterFissioner::persistentInput(PersistentIStream & is, int) {
	is >> iunit(_clMaxLight,GeV)
	>> iunit(_clMaxHeavy,GeV) >> iunit(_clMaxExotic,GeV) >> _clPowLight >> _clPowHeavy
	>> _clPowExotic >> _pSplitLight
	>> _pSplitHeavy >> _pSplitExotic
	>> _fissionCluster >> _fissionPwt
	>> iunit(_btClM,GeV) >> _iopRem
	>> iunit(_kappa, GeV/meter)
	- >> _enhanceSProb >> iunit(_m0Fission,GeV) >> _massMeasure
	+ >> _enhanceSProb >> iunit(_m0Fission,GeV) >> _massMeasure >> _dim >> _phaseSpaceWeights
	>> _hadronSpectrum
	>> _probPowFactor >> _probShift >> iunit(_kinThresholdShift,sqr(GeV));
	}

	void ClusterFissioner::doinit() {
	Interfaced::doinit();
	for ( const long& id : spectrum()->heavyHadronizingQuarks() ) {
	if ( _pSplitHeavy.find(id) == _pSplitHeavy.end() \|\|
	_clPowHeavy.find(id) == _clPowHeavy.end() \|\|
	_clMaxHeavy.find(id) == _clMaxHeavy.end() )
	throw InitException() << "not all parameters have been set for heavy quark cluster fission";
	}
	for ( const long& id : spectrum()->lightHadronizingQuarks() ) {
	if ( _fissionPwt.find(id) == _fissionPwt.end() )
	throw InitException() << "fission weights for light quarks have not been set";
	}
	}

	void ClusterFissioner::Init() {

	static ClassDocumentation<ClusterFissioner> documentation
	("Class responsibles for chopping up the clusters");

	static Reference<ClusterFissioner,HadronSpectrum> interfaceHadronSpectrum
	("HadronSpectrum",
	"Set the Hadron spectrum for this cluster fissioner.",
	&ClusterFissioner::_hadronSpectrum, false, false, true, false);

	// ClMax for light, Bottom, Charm and exotic (e.g. Susy) quarks
	static Parameter<ClusterFissioner,Energy>
	interfaceClMaxLight ("ClMaxLight","cluster max mass for light quarks (unit [GeV])",
	&ClusterFissioner::_clMaxLight, GeV, 3.35GeV, ZERO, 10.0GeV,
	false,false,false);
	static ParMap<ClusterFissioner,Energy> interfaceClMaxHeavy
	("ClMaxHeavy",
	"ClMax for heavy quarkls",
	&ClusterFissioner::_clMaxHeavy, GeV, -1, 3.35GeV, ZERO, 10.0GeV,
	false, false, Interface::upperlim);
	static Parameter<ClusterFissioner,Energy>
	interfaceClMaxExotic ("ClMaxExotic","cluster max mass for exotic quarks (unit [GeV])",
	&ClusterFissioner::_clMaxExotic, GeV, 3.35GeV, ZERO, 10.0GeV,
	false,false,false);

	// ClPow for light, Bottom, Charm and exotic (e.g. Susy) quarks
	static Parameter<ClusterFissioner,double>
	interfaceClPowLight ("ClPowLight","cluster mass exponent for light quarks",
	&ClusterFissioner::_clPowLight, 0, 2.0, 0.0, 10.0,false,false,false);
	static ParMap<ClusterFissioner,double> interfaceClPowHeavy
	("ClPowHeavy",
	"ClPow for heavy quarks",
	&ClusterFissioner::_clPowHeavy, -1, 1.0, 0.0, 10.0,
	false, false, Interface::upperlim);
	static Parameter<ClusterFissioner,double>
	interfaceClPowExotic ("ClPowExotic","cluster mass exponent for exotic quarks",
	&ClusterFissioner::_clPowExotic, 0, 2.0, 0.0, 10.0,false,false,false);

	// PSplit for light, Bottom, Charm and exotic (e.g. Susy) quarks
	static Parameter<ClusterFissioner,double>
	interfacePSplitLight ("PSplitLight","cluster mass splitting param for light quarks",
	&ClusterFissioner::_pSplitLight, 0, 1.0, 0.0, 10.0,false,false,false);
	static ParMap<ClusterFissioner,double> interfacePSplitHeavy
	("PSplitHeavy",
	"PSplit for heavy quarks",
	&ClusterFissioner::_pSplitHeavy, -1, 1.0, 0.0, 10.0,
	false, false, Interface::upperlim);
	static Parameter<ClusterFissioner,double>
	interfacePSplitExotic ("PSplitExotic","cluster mass splitting param for exotic quarks",
	&ClusterFissioner::_pSplitExotic, 0, 1.0, 0.0, 10.0,false,false,false);


	static Switch<ClusterFissioner,int> interfaceFission
	("Fission",
	"Option for different Fission options",
	&ClusterFissioner::_fissionCluster, 1, false, false);
	static SwitchOption interfaceFissionDefault
	(interfaceFission,
	"default",
	"Normal cluster fission which depends on the hadron selector class.",
	0);
	static SwitchOption interfaceFissionNew
	(interfaceFission,
	"new",
	"Alternative cluster fission which does not depend on the hadron selector class",
	1);

	static ParMap<ClusterFissioner,double> interfaceFissionPwt
	("FissionPwt",
	"The weights for quarks in the fission process.",
	&ClusterFissioner::_fissionPwt, -1, 1.0, 0.0, 10.0,
	false, false, Interface::upperlim);

	static Switch<ClusterFissioner,int> interfaceRemnantOption
	("RemnantOption",
	"Option for the treatment of remnant clusters",
	&ClusterFissioner::_iopRem, 1, false, false);
	static SwitchOption interfaceRemnantOptionSoft
	(interfaceRemnantOption,
	"Soft",
	"Both clusters produced in the fission of the beam cluster"
	" are treated as soft clusters.",
	0);
	static SwitchOption interfaceRemnantOptionHard
	(interfaceRemnantOption,
	"Hard",
	"Only the cluster containing the remnant is treated as a soft cluster.",
	1);
	static SwitchOption interfaceRemnantOptionVeryHard
	(interfaceRemnantOption,
	"VeryHard",
	"Even remnant clusters are treated as hard, i.e. all clusters the same",
	2);

	static Parameter<ClusterFissioner,Energy> interfaceBTCLM
	("SoftClusterFactor",
	"Parameter for the mass spectrum of remnant clusters",
	&ClusterFissioner::_btClM, GeV, 1.GeV, 0.1GeV, 10.0*GeV,
	false, false, Interface::limited);


	static Parameter<ClusterFissioner,Tension> interfaceStringTension
	("StringTension",
	"String tension used in vertex displacement calculation",
	&ClusterFissioner::_kappa, GeV/meter,
	1.0e15*GeV/meter, ZERO, ZERO,
	false, false, Interface::lowerlim);

	static Switch<ClusterFissioner,int> interfaceEnhanceSProb
	("EnhanceSProb",
	"Option for enhancing strangeness",
	&ClusterFissioner::_enhanceSProb, 0, false, false);
	static SwitchOption interfaceEnhanceSProbNo
	(interfaceEnhanceSProb,
	"No",
	"No strangeness enhancement.",
	0);
	static SwitchOption interfaceEnhanceSProbScaled
	(interfaceEnhanceSProb,
	"Scaled",
	"Scaled strangeness enhancement",
	1);
	static SwitchOption interfaceEnhanceSProbExponential
	(interfaceEnhanceSProb,
	"Exponential",
	"Exponential strangeness enhancement",
	2);

	static Switch<ClusterFissioner,int> interfaceMassMeasure
	("MassMeasure",
	"Option to use different mass measures",
	&ClusterFissioner::_massMeasure,0,false,false);
	static SwitchOption interfaceMassMeasureMass
	(interfaceMassMeasure,
	"Mass",
	"Mass Measure",
	0);
	static SwitchOption interfaceMassMeasureLambda
	(interfaceMassMeasure,
	"Lambda",
	"Lambda Measure",
	1);

	static Parameter<ClusterFissioner,Energy> interfaceFissionMassScale
	("FissionMassScale",
	"Cluster fission mass scale",
	&ClusterFissioner::_m0Fission, GeV, 2.0GeV, 0.1GeV, 50.*GeV,
	false, false, Interface::limited);

	static Parameter<ClusterFissioner,double> interfaceProbPowFactor
	("ProbablityPowerFactor",
	"Power factor in ClausterFissioner bell probablity function",
	&ClusterFissioner::_probPowFactor, 2.0, 1.0, 20.0,
	false, false, Interface::limited);

	static Parameter<ClusterFissioner,double> interfaceProbShift
	("ProbablityShift",
	"Shifts from the center in ClausterFissioner bell probablity function",
	&ClusterFissioner::_probShift, 0.0, -10.0, 10.0,
	false, false, Interface::limited);

	static Parameter<ClusterFissioner,Energy2> interfaceKineticThresholdShift
	("KineticThresholdShift",
	"Shifts from the kinetic threshold in ClausterFissioner",
	&ClusterFissioner::_kinThresholdShift, sqr(GeV), 0.sqr(GeV), -10.0sqr(GeV), 10.0*sqr(GeV),
	false, false, Interface::limited);

	static Switch<ClusterFissioner,int> interfaceKinematicThreshold
	("KinematicThreshold",
	"Option for using static or dynamic kinematic thresholds in cluster splittings",
	&ClusterFissioner::_kinematicThresholdChoice, 0, false, false);
	static SwitchOption interfaceKinematicThresholdStatic
	(interfaceKinematicThreshold,
	"Static",
	"Set static kinematic thresholds for cluster splittings.",
	0);
	static SwitchOption interfaceKinematicThresholdDynamic
	(interfaceKinematicThreshold,
	"Dynamic",
	"Set dynamic kinematic thresholds for cluster splittings.",
	1);

	+
	+ static Switch<ClusterFissioner,bool> interfacePhaseSpaceWeights
	+ ("PhaseSpaceWeights",
	+ "Include phase space weights.",
	+ &ClusterFissioner::_phaseSpaceWeights, false, false, false);
	+ static SwitchOption interfacePhaseSpaceWeightsYes
	+ (interfacePhaseSpaceWeights,
	+ "Yes",
	+ "Do include the effect of cluster fission phase space",
	+ true);
	+ static SwitchOption interfacePhaseSpaceWeightsNo
	+ (interfacePhaseSpaceWeights,
	+ "No",
	+ "Do not include the effect of cluster phase space",
	+ false);
	+
	+ static Parameter<ClusterFissioner,double>
	+ interfaceDim ("Dimension","Dimension in which phase space weights are calculated",
	+ &ClusterFissioner::_dim, 0, 4.0, 0.0, 10.0,false,false,false);
	+
	}

	tPVector ClusterFissioner::fission(ClusterVector & clusters, bool softUEisOn) {
	// return if no clusters
	if (clusters.empty()) return tPVector();

	/*****************
	* Loop over the (input) collection of cluster pointers, and store in
	* the vector splitClusters all the clusters that need to be split
	* (these are beam clusters, if soft underlying event is off, and
	* heavy non-beam clusters).
	********************/

	stack<ClusterPtr> splitClusters;
	for(ClusterVector::iterator it = clusters.begin() ;
	it != clusters.end() ; ++it) {
	/**************
	* Skip 3-component clusters that have been redefined (as 2-component
	* clusters) or not available clusters. The latter check is indeed
	* redundant now, but it is used for possible future extensions in which,
	* for some reasons, some of the clusters found by ClusterFinder are tagged
	* straight away as not available.
	**************/
	if((it)->isRedefined() \|\| !(it)->isAvailable()) continue;
	// if the cluster is a beam cluster add it to the vector of clusters
	// to be split or if it is heavy
	if((it)->isBeamCluster() \|\| isHeavy(it)) splitClusters.push(*it);
	}
	tPVector finalhadrons;
	cut(splitClusters, clusters, finalhadrons, softUEisOn);
	return finalhadrons;
	}

	void ClusterFissioner::cut(stack<ClusterPtr> & clusterStack,
	ClusterVector &clusters, tPVector & finalhadrons,
	bool softUEisOn) {
	/**************************************************
	* This method does the splitting of the cluster pointed by cluPtr
	* and "recursively" by all of its cluster children, if heavy. All of these
	* new children clusters are added (indeed the pointers to them) to the
	* collection of cluster pointers collecCluPtr. The method works as follows.
	* Initially the vector vecCluPtr contains just the input pointer to the
	* cluster to be split. Then it will be filled "recursively" by all
	* of the cluster's children that are heavy enough to require, in their turn,
	* to be split. In each loop, the last element of the vector vecCluPtr is
	* considered (only once because it is then removed from the vector).
	* This approach is conceptually recursive, but avoid the overhead of
	* a concrete recursive function. Furthermore it requires minimal changes
	* in the case that the fission of an heavy cluster could produce more
	* than two cluster children as assumed now.
	*
	* Draw the masses: for normal, non-beam clusters a power-like mass dist
	* is used, whereas for beam clusters a fast-decreasing exponential mass
	* dist is used instead (to avoid many iterative splitting which could
	* produce an unphysical large transverse energy from a supposed soft beam
	* remnant process).
	****************************************/
	// Here we recursively loop over clusters in the stack and cut them
	while (!clusterStack.empty()) {
	// take the last element of the vector
	ClusterPtr iCluster = clusterStack.top(); clusterStack.pop();
	// split it
	cutType ct = iCluster->numComponents() == 2 ?
	cutTwo(iCluster, finalhadrons, softUEisOn) :
	cutThree(iCluster, finalhadrons, softUEisOn);

	// There are cases when we don't want to split, even if it fails mass test
	if(!ct.first.first \|\| !ct.second.first) {
	// if an unsplit beam cluster leave if for the underlying event
	if(iCluster->isBeamCluster() && softUEisOn)
	iCluster->isAvailable(false);
	continue;
	}
	// check if clusters
	ClusterPtr one = dynamic_ptr_cast<ClusterPtr>(ct.first.first);
	ClusterPtr two = dynamic_ptr_cast<ClusterPtr>(ct.second.first);
	// is a beam cluster must be split into two clusters
	if(iCluster->isBeamCluster() && (!one\|\|!two) && softUEisOn) {
	iCluster->isAvailable(false);
	continue;
	}

	// There should always be a intermediate quark(s) from the splitting
	assert(ct.first.second && ct.second.second);
	/// \todo sort out motherless quark pairs here. Watch out for 'quark in final state' errors
	iCluster->addChild(ct.first.first);
	// iCluster->addChild(ct.first.second);
	// ct.first.second->addChild(ct.first.first);

	iCluster->addChild(ct.second.first);
	// iCluster->addChild(ct.second.second);
	// ct.second.second->addChild(ct.second.first);

	// Sometimes the clusters decay C -> H + C' rather then C -> C' + C''
	if(one) {
	clusters.push_back(one);
	if(one->isBeamCluster() && softUEisOn)
	one->isAvailable(false);
	if(isHeavy(one) && one->isAvailable())
	clusterStack.push(one);
	}
	if(two) {
	clusters.push_back(two);
	if(two->isBeamCluster() && softUEisOn)
	two->isAvailable(false);
	if(isHeavy(two) && two->isAvailable())
	clusterStack.push(two);
	}
	}
	}

	ClusterFissioner::cutType
	ClusterFissioner::cutTwo(ClusterPtr & cluster, tPVector & finalhadrons,
	bool softUEisOn) {
	// need to make sure only 2-cpt clusters get here
	assert(cluster->numComponents() == 2);
	tPPtr ptrQ1 = cluster->particle(0);
	tPPtr ptrQ2 = cluster->particle(1);
	Energy Mc = cluster->mass();
	assert(ptrQ1);
	assert(ptrQ2);

	// And check if those particles are from a beam remnant
	bool rem1 = cluster->isBeamRemnant(0);
	bool rem2 = cluster->isBeamRemnant(1);
	// workout which distribution to use
	bool soft1(false),soft2(false);
	switch (_iopRem) {
	case 0:
	soft1 = rem1 \|\| rem2;
	soft2 = rem2 \|\| rem1;
	break;
	case 1:
	soft1 = rem1;
	soft2 = rem2;
	break;
	}
	// Initialization for the exponential ("soft") mass distribution.
	static const int max_loop = 1000;
	int counter = 0;
	Energy Mc1 = ZERO, Mc2 = ZERO,m1=ZERO,m2=ZERO,m=ZERO;
	tcPDPtr toHadron1, toHadron2;
	PPtr newPtr1 = PPtr ();
	PPtr newPtr2 = PPtr ();
	bool succeeded = false;
	Lorentz5Momentum pClu1, pClu2, pQ1, pQone, pQtwo, pQ2;
	do
	{
	succeeded = false;
	++counter;
	// get a flavour for the qqbar pair
	drawNewFlavour(newPtr1,newPtr2,cluster);
	// check for right ordering
	assert (ptrQ2);
	assert (newPtr2);
	assert (ptrQ2->dataPtr());
	assert (newPtr2->dataPtr());
	if(cantMakeHadron(ptrQ1, newPtr1) \|\| cantMakeHadron(ptrQ2, newPtr2)) {
	swap(newPtr1, newPtr2);
	// check again
	if(cantMakeHadron(ptrQ1, newPtr1) \|\| cantMakeHadron(ptrQ2, newPtr2)) {
	throw Exception()
	<< "ClusterFissioner cannot split the cluster ("
	<< ptrQ1->PDGName() << ' ' << ptrQ2->PDGName()
	<< ") into hadrons.\n" << Exception::runerror;
	}
	}
	// Check that new clusters can produce particles and there is enough
	// phase space to choose the drawn flavour
	m1 = ptrQ1->data().constituentMass();
	m2 = ptrQ2->data().constituentMass();
	m = newPtr1->data().constituentMass();
	// Do not split in the case there is no phase space available
	if(Mc < m1+m + m2+m) continue;

	pQ1.setMass(m1);
	pQone.setMass(m);
	pQtwo.setMass(m);
	pQ2.setMass(m2);

	pair<Energy,Energy> res = drawNewMasses(Mc, soft1, soft2, pClu1, pClu2,
	ptrQ1, pQ1, newPtr1, pQone,
	newPtr2, pQtwo, ptrQ2, pQ2);

	// derive the masses of the children
	Mc1 = res.first;
	Mc2 = res.second;
	// static kinematic threshold
	if(_kinematicThresholdChoice == 0) {
	if(Mc1 < m1+m \|\| Mc2 < m+m2 \|\| Mc1+Mc2 > Mc) continue;
	// dynamic kinematic threshold
	} else if(_kinematicThresholdChoice == 1) {
	bool C1 = ( sqr(Mc1) )/( sqr(m1) + sqr(m) + _kinThresholdShift ) < 1.0 ? true : false;
	bool C2 = ( sqr(Mc2) )/( sqr(m2) + sqr(m) + _kinThresholdShift ) < 1.0 ? true : false;
	bool C3 = ( sqr(Mc1) + sqr(Mc2) )/( sqr(Mc) ) > 1.0 ? true : false;

	if( C1 \|\| C2 \|\| C3 ) continue;
	}

	+ if ( _phaseSpaceWeights ) {
	+ if ( phaseSpaceVeto(Mc,Mc1,Mc2,m,m1,m2) )
	+ continue;
	+ }
	+
	/**************************
	* New (not present in Fortran Herwig):
	* check whether the fragment masses Mc1 and Mc2 are above the
	* threshold for the production of the lightest pair of hadrons with the
	* right flavours. If not, then set by hand the mass to the lightest
	* single hadron with the right flavours, in order to solve correctly
	* the kinematics, and (later in this method) create directly such hadron
	* and add it to the children hadrons of the cluster that undergoes the
	* fission (i.e. the one pointed by iCluPtr). Notice that in this special
	* case, the heavy cluster that undergoes the fission has one single
	* cluster child and one single hadron child. We prefer this approach,
	* rather than to create a light cluster, with the mass set equal to
	* the lightest hadron, and let then the class LightClusterDecayer to do
	* the job to decay it to that single hadron, for two reasons:
	* First, because the sum of the masses of the two constituents can be,
	* in this case, greater than the mass of that hadron, hence it would
	* be impossible to solve the kinematics for such two components, and
	* therefore we would have a cluster whose components are undefined.
	* Second, the algorithm is faster, because it avoids the reshuffling
	* procedure that would be necessary if we used LightClusterDecayer
	* to decay the light cluster to the lightest hadron.
	****************************/
	// override chosen masses if needed
	toHadron1 = _hadronSpectrum->chooseSingleHadron(ptrQ1->dataPtr(), newPtr1->dataPtr(),Mc1);
	if(toHadron1) { Mc1 = toHadron1->mass(); pClu1.setMass(Mc1); }
	toHadron2 = _hadronSpectrum->chooseSingleHadron(ptrQ2->dataPtr(), newPtr2->dataPtr(),Mc2);
	if(toHadron2) { Mc2 = toHadron2->mass(); pClu2.setMass(Mc2); }
	// if a beam cluster not allowed to decay to hadrons
	if(cluster->isBeamCluster() && (toHadron1\|\|toHadron2) && softUEisOn)
	continue;
	// Check if the decay kinematics is still possible: if not then
	// force the one-hadron decay for the other cluster as well.
	if(Mc1 + Mc2 > Mc) {
	if(!toHadron1) {
	toHadron1 = _hadronSpectrum->chooseSingleHadron(ptrQ1->dataPtr(), newPtr1->dataPtr(),Mc-Mc2);
	if(toHadron1) { Mc1 = toHadron1->mass(); pClu1.setMass(Mc1); }
	}
	else if(!toHadron2) {
	toHadron2 = _hadronSpectrum->chooseSingleHadron(ptrQ2->dataPtr(), newPtr2->dataPtr(),Mc-Mc1);
	if(toHadron2) { Mc2 = toHadron2->mass(); pClu2.setMass(Mc2); }
	}
	}
	succeeded = (Mc >= Mc1+Mc2);
	}
	while (!succeeded && counter < max_loop);

	if(counter >= max_loop) {
	static const PPtr null = PPtr();
	return cutType(PPair(null,null),PPair(null,null));
	}

	// Determined the (5-components) momenta (all in the LAB frame)
	Lorentz5Momentum pClu = cluster->momentum(); // known
	Lorentz5Momentum p0Q1 = ptrQ1->momentum(); // known (mom Q1 before fission)
	calculateKinematics(pClu,p0Q1,toHadron1,toHadron2,
	pClu1,pClu2,pQ1,pQone,pQtwo,pQ2);

	/******************
	* The previous methods have determined the kinematics and positions
	* of C -> C1 + C2.
	* In the case that one of the two product is light, that means either
	* decayOneHadronClu1 or decayOneHadronClu2 is true, then the momenta
	* of the components of that light product have not been determined,
	* and a (light) cluster will not be created: the heavy father cluster
	* decays, in this case, into a single (not-light) cluster and a
	* single hadron. In the other, "normal", cases the father cluster
	* decays into two clusters, each of which has well defined components.
	* Notice that, in the case of components which point to particles, the
	* momenta of the components is properly set to the new values, whereas
	* we do not change the momenta of the pointed particles, because we
	* want to keep all of the information (that is the new momentum of a
	* component after the splitting, which is contained in the _momentum
	* member of the Component class, and the (old) momentum of that component
	* before the splitting, which is contained in the momentum of the
	* pointed particle). Please not make confusion of this only apparent
	* inconsistency!
	********************/
	LorentzPoint posC,pos1,pos2;
	posC = cluster->vertex();
	calculatePositions(pClu, posC, pClu1, pClu2, pos1, pos2);
	cutType rval;
	if(toHadron1) {
	rval.first = produceHadron(toHadron1, newPtr1, pClu1, pos1);
	finalhadrons.push_back(rval.first.first);
	}
	else {
	rval.first = produceCluster(ptrQ1, newPtr1, pClu1, pos1, pQ1, pQone, rem1);
	}
	if(toHadron2) {
	rval.second = produceHadron(toHadron2, newPtr2, pClu2, pos2);
	finalhadrons.push_back(rval.second.first);
	}
	else {
	rval.second = produceCluster(ptrQ2, newPtr2, pClu2, pos2, pQ2, pQtwo, rem2);
	}
	return rval;
	}


	ClusterFissioner::cutType
	ClusterFissioner::cutThree(ClusterPtr & cluster, tPVector & finalhadrons,
	bool softUEisOn) {
	// need to make sure only 3-cpt clusters get here
	assert(cluster->numComponents() == 3);
	// extract quarks
	tPPtr ptrQ[3] = {cluster->particle(0),cluster->particle(1),cluster->particle(2)};
	assert( ptrQ[0] && ptrQ[1] && ptrQ[2] );
	// find maximum mass pair
	Energy mmax(ZERO);
	Lorentz5Momentum pDiQuark;
	int iq1(-1),iq2(-1);
	Lorentz5Momentum psum;
	for(int q1=0;q1<3;++q1) {
	psum+= ptrQ[q1]->momentum();
	for(int q2=q1+1;q2<3;++q2) {
	Lorentz5Momentum ptest = ptrQ[q1]->momentum()+ptrQ[q2]->momentum();
	ptest.rescaleMass();
	Energy mass = ptest.m();
	if(mass>mmax) {
	mmax = mass;
	pDiQuark = ptest;
	iq1 = q1;
	iq2 = q2;
	}
	}
	}
	// and the spectators
	int iother(-1);
	for(int ix=0;ix<3;++ix) if(ix!=iq1&&ix!=iq2) iother=ix;
	assert(iq1>=0&&iq2>=0&&iother>=0);

	// And check if those particles are from a beam remnant
	bool rem1 = cluster->isBeamRemnant(iq1);
	bool rem2 = cluster->isBeamRemnant(iq2);
	// workout which distribution to use
	bool soft1(false),soft2(false);
	switch (_iopRem) {
	case 0:
	soft1 = rem1 \|\| rem2;
	soft2 = rem2 \|\| rem1;
	break;
	case 1:
	soft1 = rem1;
	soft2 = rem2;
	break;
	}
	// Initialization for the exponential ("soft") mass distribution.
	static const int max_loop = 1000;
	int counter = 0;
	Energy Mc1 = ZERO, Mc2 = ZERO, m1=ZERO, m2=ZERO, m=ZERO;
	tcPDPtr toHadron;
	bool toDiQuark(false);
	PPtr newPtr1 = PPtr(),newPtr2 = PPtr();
	PDPtr diquark;
	bool succeeded = false;
	Lorentz5Momentum pClu1, pClu2, pQ1, pQone, pQtwo, pQ2;
	do {
	succeeded = false;
	++counter;

	// get a flavour for the qqbar pair
	drawNewFlavour(newPtr1,newPtr2,cluster);

	// randomly pick which will be (anti)diquark and which a mesonic cluster
	if(UseRandom::rndbool()) {
	swap(iq1,iq2);
	swap(rem1,rem2);
	}
	// check first order
	if(cantMakeHadron(ptrQ[iq1], newPtr1) \|\| !spectrum()->canMakeDiQuark(ptrQ[iq2], newPtr2)) {
	swap(newPtr1,newPtr2);
	}
	// check again
	if(cantMakeHadron(ptrQ[iq1], newPtr1) \|\| !spectrum()->canMakeDiQuark(ptrQ[iq2], newPtr2)) {
	throw Exception()
	<< "ClusterFissioner cannot split the cluster ("
	<< ptrQ[iq1]->PDGName() << ' ' << ptrQ[iq2]->PDGName()
	<< ") into a hadron and diquark.\n" << Exception::runerror;
	}
	// Check that new clusters can produce particles and there is enough
	// phase space to choose the drawn flavour
	m1 = ptrQ[iq1]->data().constituentMass();
	m2 = ptrQ[iq2]->data().constituentMass();
	m = newPtr1->data().constituentMass();
	// Do not split in the case there is no phase space available
	if(mmax < m1+m + m2+m) continue;

	pQ1.setMass(m1);
	pQone.setMass(m);
	pQtwo.setMass(m);
	pQ2.setMass(m2);

	pair<Energy,Energy> res = drawNewMasses(mmax, soft1, soft2, pClu1, pClu2,
	ptrQ[iq1], pQ1, newPtr1, pQone,
	newPtr2, pQtwo, ptrQ[iq1], pQ2);

	Mc1 = res.first; Mc2 = res.second;

	if(Mc1 < m1+m \|\| Mc2 < m+m2 \|\| Mc1+Mc2 > mmax) continue;
	+
	+ if ( _phaseSpaceWeights ) {
	+ if ( phaseSpaceVeto(mmax,Mc1,Mc2,m,m1,m2) )
	+ continue;
	+ }
	+
	// check if need to force meson clster to hadron
	toHadron = _hadronSpectrum->chooseSingleHadron(ptrQ[iq1]->dataPtr(), newPtr1->dataPtr(),Mc1);
	if(toHadron) { Mc1 = toHadron->mass(); pClu1.setMass(Mc1); }
	// check if need to force diquark cluster to be on-shell
	toDiQuark = false;
	diquark = spectrum()->makeDiquark(ptrQ[iq2]->dataPtr(), newPtr2->dataPtr());
	if(Mc2 < diquark->constituentMass()) {
	Mc2 = diquark->constituentMass(); pClu2.setMass(Mc2);
	toDiQuark = true;
	}
	// if a beam cluster not allowed to decay to hadrons
	if(cluster->isBeamCluster() && toHadron && softUEisOn)
	continue;
	// Check if the decay kinematics is still possible: if not then
	// force the one-hadron decay for the other cluster as well.
	if(Mc1 + Mc2 > mmax) {
	if(!toHadron) {
	toHadron = _hadronSpectrum->chooseSingleHadron(ptrQ[iq1]->dataPtr(), newPtr1->dataPtr(),mmax-Mc2);
	if(toHadron) { Mc1 = toHadron->mass(); pClu1.setMass(Mc1); }
	}
	else if(!toDiQuark) {
	Mc2 = _hadronSpectrum->massLightestHadron(ptrQ[iq2]->dataPtr(), newPtr2->dataPtr()); pClu2.setMass(Mc2);
	toDiQuark = true;
	}
	}
	succeeded = (mmax >= Mc1+Mc2);
	}
	while (!succeeded && counter < max_loop);
	// check no of tries
	if(counter >= max_loop) return cutType();

	// Determine the (5-components) momenta (all in the LAB frame)
	Lorentz5Momentum p0Q1 = ptrQ[iq1]->momentum();
	calculateKinematics(pDiQuark,p0Q1,toHadron,toDiQuark,
	pClu1,pClu2,pQ1,pQone,pQtwo,pQ2);
	// positions of the new clusters
	LorentzPoint pos1,pos2;
	Lorentz5Momentum pBaryon = pClu2+ptrQ[iother]->momentum();
	calculatePositions(cluster->momentum(), cluster->vertex(), pClu1, pBaryon, pos1, pos2);
	// first the mesonic cluster/meson
	cutType rval;
	if(toHadron) {
	rval.first = produceHadron(toHadron, newPtr1, pClu1, pos1);
	finalhadrons.push_back(rval.first.first);
	}
	else {
	rval.first = produceCluster(ptrQ[iq1], newPtr1, pClu1, pos1, pQ1, pQone, rem1);
	}
	if(toDiQuark) {
	rem2 \|= cluster->isBeamRemnant(iother);
	PPtr newDiQuark = diquark->produceParticle(pClu2);
	rval.second = produceCluster(newDiQuark, ptrQ[iother], pBaryon, pos2, pClu2,
	ptrQ[iother]->momentum(), rem2);
	}
	else {
	rval.second = produceCluster(ptrQ[iq2], newPtr2, pBaryon, pos2, pQ2, pQtwo, rem2,
	ptrQ[iother],cluster->isBeamRemnant(iother));
	}
	cluster->isAvailable(false);
	return rval;
	}

	ClusterFissioner::PPair
	ClusterFissioner::produceHadron(tcPDPtr hadron, tPPtr newPtr, const Lorentz5Momentum &a,
	const LorentzPoint &b) const {
	PPair rval;
	if(hadron->coloured()) {
	rval.first = (_hadronSpectrum->lightestHadron(hadron,newPtr->dataPtr()))->produceParticle();
	}
	else
	rval.first = hadron->produceParticle();
	rval.second = newPtr;
	rval.first->set5Momentum(a);
	rval.first->setVertex(b);
	return rval;
	}

	ClusterFissioner::PPair ClusterFissioner::produceCluster(tPPtr ptrQ, tPPtr newPtr,
	const Lorentz5Momentum & a,
	const LorentzPoint & b,
	const Lorentz5Momentum & c,
	const Lorentz5Momentum & d,
	bool isRem,
	tPPtr spect, bool remSpect) const {
	PPair rval;
	rval.second = newPtr;
	ClusterPtr cluster = !spect ? new_ptr(Cluster(ptrQ,rval.second)) : new_ptr(Cluster(ptrQ,rval.second,spect));
	rval.first = cluster;
	cluster->set5Momentum(a);
	cluster->setVertex(b);
	assert(cluster->particle(0)->id() == ptrQ->id());
	cluster->particle(0)->set5Momentum(c);
	cluster->particle(1)->set5Momentum(d);
	cluster->setBeamRemnant(0,isRem);
	if(remSpect) cluster->setBeamRemnant(2,remSpect);
	return rval;
	}

	void ClusterFissioner::drawNewFlavour(PPtr& newPtrPos,PPtr& newPtrNeg) const {

	// Flavour is assumed to be only u, d, s, with weights
	// (which are not normalized probabilities) given
	// by the same weights as used in HadronsSelector for
	// the decay of clusters into two hadrons.


	Selector<long> choice;
	switch(_fissionCluster){
	case 0:
	for ( const long& id : spectrum()->lightHadronizingQuarks() )
	choice.insert(_hadronSpectrum->pwtQuark(id),id);
	break;
	case 1:
	for ( const long& id : spectrum()->lightHadronizingQuarks() )
	choice.insert(_fissionPwt.find(id)->second,id);
	break;
	default :
	assert(false);
	}
	long idNew = choice.select(UseRandom::rnd());
	newPtrPos = getParticle(idNew);
	newPtrNeg = getParticle(-idNew);
	assert (newPtrPos);
	assert(newPtrNeg);
	assert (newPtrPos->dataPtr());
	assert(newPtrNeg->dataPtr());

	}

	void ClusterFissioner::drawNewFlavourEnhanced(PPtr& newPtrPos,PPtr& newPtrNeg,
	Energy2 mass2) const {

	if ( spectrum()->gluonId() != ParticleID::g )
	throw Exception() << "strange enhancement only working with Standard Model hadronization"
	<< Exception::runerror;

	// Flavour is assumed to be only u, d, s, with weights
	// (which are not normalized probabilities) given
	// by the same weights as used in HadronsSelector for
	// the decay of clusters into two hadrons.

	double prob_d = 0.;
	double prob_u = 0.;
	double prob_s = 0.;
	double scale = abs(double(sqr(_m0Fission)/mass2));
	// Choose which splitting weights you wish to use
	switch(_fissionCluster){
	// 0: ClusterFissioner and ClusterDecayer use the same weights
	case 0:
	prob_d = _hadronSpectrum->pwtQuark(ParticleID::d);
	prob_u = _hadronSpectrum->pwtQuark(ParticleID::u);
	/* Strangeness enhancement:
	Case 1: probability scaling
	Case 2: Exponential scaling
	*/
	if (_enhanceSProb == 1)
	prob_s = (_maxScale < scale) ? 0. : pow(_hadronSpectrum->pwtQuark(ParticleID::s),scale);
	else if (_enhanceSProb == 2)
	prob_s = (_maxScale < scale) ? 0. : exp(-scale);
	break;
	/* 1: ClusterFissioner uses its own unique set of weights,
	i.e. decoupled from ClusterDecayer */
	case 1:
	prob_d = _fissionPwt.find(ParticleID::d)->second;
	prob_u = _fissionPwt.find(ParticleID::u)->second;
	if (_enhanceSProb == 1)
	prob_s = (_maxScale < scale) ? 0. : pow(_fissionPwt.find(ParticleID::s)->second,scale);
	else if (_enhanceSProb == 2)
	prob_s = (_maxScale < scale) ? 0. : exp(-scale);
	break;
	default:
	assert(false);
	}

	int choice = UseRandom::rnd3(prob_u, prob_d, prob_s);
	long idNew = 0;
	switch (choice) {
	case 0: idNew = ThePEG::ParticleID::u; break;
	case 1: idNew = ThePEG::ParticleID::d; break;
	case 2: idNew = ThePEG::ParticleID::s; break;
	}
	newPtrPos = getParticle(idNew);
	newPtrNeg = getParticle(-idNew);
	assert (newPtrPos);
	assert(newPtrNeg);
	assert (newPtrPos->dataPtr());
	assert(newPtrNeg->dataPtr());

	}


	Energy2 ClusterFissioner::clustermass(const ClusterPtr & cluster) const {
	Lorentz5Momentum pIn = cluster->momentum();
	Energy2 endpointmass2 = sqr(cluster->particle(0)->mass() +
	cluster->particle(1)->mass());
	Energy2 singletm2 = pIn.m2();
	// Return either the cluster mass, or the lambda measure
	return (_massMeasure == 0) ? singletm2 : singletm2 - endpointmass2;
	}


	Energy ClusterFissioner::drawChildMass(const Energy M, const Energy m1,
	const Energy m2, const Energy m,
	const double expt, const bool soft) const {

	/***************************
	* This method, given in input the cluster mass Mclu of an heavy cluster C,
	* made of consituents of masses m1 and m2, draws the masses Mclu1 and Mclu2
	* of, respectively, the children cluster C1, made of constituent masses m1
	* and m, and cluster C2, of mass Mclu2 and made of constituent masses m2
	* and m. The mass is extracted from one of the two following mass
	* distributions:
	* --- power-like ("normal" distribution)
	* d(Prob) / d(M^exponent) = const
	* where the exponent can be different from the two children C1 (exp1)
	* and C2 (exponent2).
	* --- exponential ("soft" distribution)
	* d(Prob) / d(M^2) = exp(-b*M)
	* where b = 2.0 / average.
	* Such distributions are limited below by the masses of
	* the constituents quarks, and above from the mass of decaying cluster C.
	* The choice of which of the two mass distributions to use for each of the
	* two cluster children is dictated by iRemnant (see below).
	* If the number of attempts to extract a pair of mass values that are
	* kinematically acceptable is above some fixed number (max_loop, see below)
	* the method gives up and returns false; otherwise, when it succeeds, it
	* returns true.
	*
	* These distributions have been modified from HERWIG:
	* Before these were:
	* Mclu1 = m1 + (Mclu - m1 - m2)*pow( rnd(), 1.0/exponent1 );
	* The new one coded here is a more efficient version, same density
	* but taking into account 'in phase space from' beforehand
	***************************/
	// hard cluster
	if(!soft) {
	return pow(UseRandom::rnd(pow((M-m1-m2-m)*UnitRemoval::InvE, expt),
	pow(m*UnitRemoval::InvE, expt)), 1./expt
	)*UnitRemoval::E + m1;
	}
	// Otherwise it uses a soft mass distribution
	else {
	static const InvEnergy b = 2.0 / _btClM;
	Energy max = M-m1-m2-2.0*m;
	double rmin = b*max;
	rmin = ( rmin < 50 ) ? exp(-rmin) : 0.;
	double r1;
	do {
	r1 = UseRandom::rnd(rmin, 1.0) * UseRandom::rnd(rmin, 1.0);
	}
	while (r1 < rmin);
	return m1 + m - log(r1)/b;
	}
	}


	void ClusterFissioner::calculateKinematics(const Lorentz5Momentum & pClu,
	const Lorentz5Momentum & p0Q1,
	const bool toHadron1,
	const bool toHadron2,
	Lorentz5Momentum & pClu1,
	Lorentz5Momentum & pClu2,
	Lorentz5Momentum & pQ1,
	Lorentz5Momentum & pQbar,
	Lorentz5Momentum & pQ,
	Lorentz5Momentum & pQ2bar) const {

	/******************
	* This method solves the kinematics of the two body cluster decay:
	* C (Q1 Q2bar) ---> C1 (Q1 Qbar) + C2 (Q Q2bar)
	* In input we receive the momentum of C, pClu, and the momentum
	* of the quark Q1 (constituent of C), p0Q1, both in the LAB frame.
	* Furthermore, two boolean variables inform whether the two fission
	* products (C1, C2) decay immediately into a single hadron (in which
	* case the cluster itself is identify with that hadron) and we do
	* not have to solve the kinematics of the components (Q1,Qbar) for
	* C1 and (Q,Q2bar) for C2.
	* The output is given by the following momenta (all 5-components,
	* and all in the LAB frame):
	* pClu1 , pClu2 respectively of C1 , C2
	* pQ1 , pQbar respectively of Q1 , Qbar in C1
	* pQ , pQ2bar respectively of Q , Q2 in C2
	* The assumption, suggested from the string model, is that, in C frame,
	* C1 and its constituents Q1 and Qbar are collinear, and collinear to
	* the direction of Q1 in C (that is before cluster decay); similarly,
	* (always in the C frame) C2 and its constituents Q and Q2bar are
	* collinear (and therefore anti-collinear with C1,Q1,Qbar).
	* The solution is then obtained by using Lorentz boosts, as follows.
	* The kinematics of C1 and C2 is solved in their parent C frame,
	* and then boosted back in the LAB. The kinematics of Q1 and Qbar
	* is solved in their parent C1 frame and then boosted back in the LAB;
	* similarly, the kinematics of Q and Q2bar is solved in their parent
	* C2 frame and then boosted back in the LAB. In each of the three
	* "two-body decay"-like cases, we use the fact that the direction
	* of the motion of the decay products is known in the rest frame of
	* their parent. This is obvious for the first case in which the
	* parent rest frame is C; but it is also true in the other two cases
	* where the rest frames are C1 and C2. This is because C1 and C2
	* are boosted w.r.t. C in the same direction where their components,
	* respectively (Q1,Qbar) and (Q,Q2bar) move in C1 and C2 rest frame
	* respectively.
	* Of course, although the notation used assumed that C = (Q1 Q2bar)
	* where Q1 is a quark and Q2bar an antiquark, indeed everything remain
	* unchanged also in all following cases:
	* Q1 quark, Q2bar antiquark; --> Q quark;
	* Q1 antiquark , Q2bar quark; --> Q antiquark;
	* Q1 quark, Q2bar diquark; --> Q quark
	* Q1 antiquark, Q2bar anti-diquark; --> Q antiquark
	* Q1 diquark, Q2bar quark --> Q antiquark
	* Q1 anti-diquark, Q2bar antiquark; --> Q quark
	**************************/

	// Calculate the unit three-vector, in the C frame, along which
	// all of the constituents and children clusters move.
	Lorentz5Momentum u(p0Q1);
	u.boost( -pClu.boostVector() ); // boost from LAB to C
	// the unit three-vector is then u.vect().unit()

	// Calculate the momenta of C1 and C2 in the (parent) C frame first,
	// where the direction of C1 is u.vect().unit(), and then boost back in the
	// LAB frame.

	if (pClu.m() < pClu1.mass() + pClu2.mass() ) {
	throw Exception() << "Impossible Kinematics in ClusterFissioner::calculateKinematics() (A)"
	<< Exception::eventerror;
	}
	Kinematics::twoBodyDecay(pClu, pClu1.mass(), pClu2.mass(),
	u.vect().unit(), pClu1, pClu2);

	// In the case that cluster1 does not decay immediately into a single hadron,
	// calculate the momenta of Q1 (as constituent of C1) and Qbar in the
	// (parent) C1 frame first, where the direction of Q1 is u.vect().unit(),
	// and then boost back in the LAB frame.
	if(!toHadron1) {
	if (pClu1.m() < pQ1.mass() + pQbar.mass() ) {
	throw Exception() << "Impossible Kinematics in ClusterFissioner::calculateKinematics() (B)"
	<< Exception::eventerror;
	}
	Kinematics::twoBodyDecay(pClu1, pQ1.mass(), pQbar.mass(),
	u.vect().unit(), pQ1, pQbar);
	}

	// In the case that cluster2 does not decay immediately into a single hadron,
	// Calculate the momenta of Q and Q2bar (as constituent of C2) in the
	// (parent) C2 frame first, where the direction of Q is u.vect().unit(),
	// and then boost back in the LAB frame.
	if(!toHadron2) {
	if (pClu2.m() < pQ.mass() + pQ2bar.mass() ) {
	throw Exception() << "Impossible Kinematics in ClusterFissioner::calculateKinematics() (C)"
	<< Exception::eventerror;
	}
	Kinematics::twoBodyDecay(pClu2, pQ.mass(), pQ2bar.mass(),
	u.vect().unit(), pQ, pQ2bar);
	}
	}


	void ClusterFissioner::calculatePositions(const Lorentz5Momentum & pClu,
	const LorentzPoint & positionClu,
	const Lorentz5Momentum & pClu1,
	const Lorentz5Momentum & pClu2,
	LorentzPoint & positionClu1,
	LorentzPoint & positionClu2) const {
	// Determine positions of cluster children.
	// See Marc Smith's thesis, page 127, formulas (4.122) and (4.123).
	Energy Mclu = pClu.m();
	Energy Mclu1 = pClu1.m();
	Energy Mclu2 = pClu2.m();

	// Calculate the unit three-vector, in the C frame, along which
	// children clusters move.
	Lorentz5Momentum u(pClu1);
	u.boost( -pClu.boostVector() ); // boost from LAB to C frame

	// the unit three-vector is then u.vect().unit()

	Energy pstarChild = Kinematics::pstarTwoBodyDecay(Mclu,Mclu1,Mclu2);

	// First, determine the relative positions of the children clusters
	// in the parent cluster reference frame.

	Energy2 mag2 = u.vect().mag2();
	InvEnergy fact = mag2>ZERO ? 1./sqrt(mag2) : 1./GeV;

	Length x1 = ( 0.25Mclu + 0.5( pstarChild + (sqr(Mclu2) - sqr(Mclu1))/(2.0*Mclu)))/_kappa;
	Length t1 = Mclu/_kappa - x1;
	LorentzDistance distanceClu1( x1 * fact * u.vect(), t1 );

	Length x2 = (-0.25Mclu + 0.5(-pstarChild + (sqr(Mclu2) - sqr(Mclu1))/(2.0*Mclu)))/_kappa;
	Length t2 = Mclu/_kappa + x2;
	LorentzDistance distanceClu2( x2 * fact * u.vect(), t2 );

	// Then, transform such relative positions from the parent cluster
	// reference frame to the Lab frame.
	distanceClu1.boost( pClu.boostVector() );
	distanceClu2.boost( pClu.boostVector() );

	// Finally, determine the absolute positions in the Lab frame.
	positionClu1 = positionClu + distanceClu1;
	positionClu2 = positionClu + distanceClu2;

	}

	bool ClusterFissioner::ProbablityFunction(double scale, double threshold) {
	double cut = UseRandom::rnd(0.0,1.0);
	return 1./(1.+pow(abs((threshold-_probShift)/scale),_probPowFactor)) > cut ? true : false;
	}

	bool ClusterFissioner::isHeavy(tcClusterPtr clu) {
	// particle data for constituents
	tcPDPtr cptr[3]={tcPDPtr(),tcPDPtr(),tcPDPtr()};
	for(size_t ix=0;ix<min(clu->numComponents(),3);++ix) {
	cptr[ix]=clu->particle(ix)->dataPtr();
	}
	// different parameters for exotic, bottom and charm clusters
	double clpow = !spectrum()->isExotic(cptr[0],cptr[1],cptr[1]) ? _clPowLight : _clPowExotic;
	Energy clmax = !spectrum()->isExotic(cptr[0],cptr[1],cptr[1]) ? _clMaxLight : _clMaxExotic;
	for ( const long& id : spectrum()->heavyHadronizingQuarks() ) {
	if ( spectrum()->hasHeavy(id,cptr[0],cptr[1],cptr[1]) ) {
	clpow = _clPowHeavy[id];
	clmax = _clMaxHeavy[id];
	}
	}
	// required test for SUSY clusters, since aboveCutoff alone
	// cannot guarantee (Mc > m1 + m2 + 2*m) in cut()
	static const Energy minmass
	= getParticleData(ParticleID::d)->constituentMass();
	bool aboveCutoff = false, canSplitMinimally = false;
	// static kinematic threshold
	if(_kinematicThresholdChoice == 0) {
	aboveCutoff = (
	pow(clu->mass()*UnitRemoval::InvE , clpow)
	>
	pow(clmax*UnitRemoval::InvE, clpow)
	+ pow(clu->sumConstituentMasses()*UnitRemoval::InvE, clpow)
	);

	canSplitMinimally = clu->mass() > clu->sumConstituentMasses() + 2.0 * minmass;
	}
	// dynamic kinematic threshold
	else if(_kinematicThresholdChoice == 1) {
	//some smooth probablity function to create a dynamic thershold
	double scale = pow(clu->mass()/GeV , clpow);
	double threshold = pow(clmax/GeV, clpow)
	+ pow(clu->sumConstituentMasses()/GeV, clpow);
	aboveCutoff = ProbablityFunction(scale,threshold);

	scale = clu->mass()/GeV;
	threshold = clu->sumConstituentMasses()/GeV + 2.0 * minmass/GeV;

	canSplitMinimally = ProbablityFunction(scale,threshold);
	}

	return aboveCutoff && canSplitMinimally;
	}
	diff --git a/Hadronization/ClusterFissioner.h b/Hadronization/ClusterFissioner.h
	--- a/Hadronization/ClusterFissioner.h
	+++ b/Hadronization/ClusterFissioner.h
	@@ -1,519 +1,558 @@
	// -- C++ --
	//
	// ClusterFissioner.h is a part of Herwig - A multi-purpose Monte Carlo event generator
	// Copyright (C) 2002-2019 The Herwig Collaboration
	//
	// Herwig is licenced under version 3 of the GPL, see COPYING for details.
	// Please respect the MCnet academic guidelines, see GUIDELINES for details.
	//
	#ifndef HERWIG_ClusterFissioner_H
	#define HERWIG_ClusterFissioner_H

	#include <ThePEG/Interface/Interfaced.h>
	#include "CluHadConfig.h"
	#include "ClusterFissioner.fh"
	#include "HadronSpectrum.h"

	namespace Herwig {
	using namespace ThePEG;

	//class Cluster; // forward declaration

	/** \ingroup Hadronization
	* \class ClusterFissioner
	* \brief This class handles clusters which are too heavy.
	* \author Philip Stephens
	* \author Alberto Ribon
	* \author Stefan Gieseke
	*
	* This class does the job of chopping up either heavy clusters or beam
	* clusters in two lighter ones. The procedure is repeated recursively until
	* all of the cluster children have masses below some threshold values.
	*
	* For the beam remnant clusters, at the moment what is done is the following.
	* In the case that the soft underlying event is switched on, the
	* beam remnant clusters are tagged as not available,
	* therefore they will not be treated at all during the hadronization.
	* In the case instead that the soft underlying event is switched off,
	* then the beam remnant clusters are treated exactly as "normal" clusters,
	* with the only exception of the mass spectrum used to generate the
	* cluster children masses. For non-beam clusters, the masses of the cluster
	* children are draw from a power-like mass distribution; for beam clusters,
	* according to the value of the flag _IOpRem, either both
	* children masses are draw from a fast-decreasing exponential mass
	* distribution (case _IOpRem == 0, or, indendently by
	* _IOpRem, in the special case that the beam cluster contains two
	* beam remnants), or one mass from the exponential distribution (corresponding
	* of the cluster child with the beam remnant) and the other with the usual
	* power-like distribution (case _IOpRem == 1, which is the
	* default one, as in Herwig 6.3).
	*
	* The reason behind the use of a fast-decreasing exponential distribution
	* is that to avoid a large transverse energy from the many sequential
	* fissions that would otherwise occur due to the typical large cluster
	* mass of beam clusters. Using instead an exponential distribution
	* the masses of the two cluster children will be very small (order of
	* GeV).
	*
	* The rationale behind the implementation of the splitting of clusters
	* has been to preserve all of the information about such splitting
	* process. More explicitly a ThePEG::Step class is passed in and the
	* new clusters are added to the step as the decay products of the
	* heavy cluster. This approach has the twofold
	* advantage to provide all of the information that could be needed
	* (expecially in future developments), without any information loss,
	* and furthermore it allows a better debugging.
	*
	* @see \ref ClusterFissionerInterfaces "The interfaces"
	* defined for ClusterFissioner.
	*/
	class ClusterFissioner: public Interfaced {

	public:

	/** @name Standard constructors and destructors. */
	//@{
	/**
	* Default constructor.
	*/
	ClusterFissioner();

	//@}

	/** Splits the clusters which are too heavy.
	*
	* Split either heavy clusters or beam clusters recursively until all
	* children have mass below some threshold. Heavy clusters are those that
	* satisfy the condition
	* \f[ M^P > C^P + S^P \f]
	* where \f$ M \f$ is the clusters mass, \f$ P \f$ is the parameter
	* ClPow, \f$ C \f$ is the parameter ClMax and \f$ S \f$ is the
	* sum of the clusters constituent partons.
	* For beam clusters, they are split only if the soft underlying event
	* is switched off, otherwise these clusters will be tagged as unavailable
	* and they will not be treated by the hadronization altogether.
	* In the case beam clusters will be split, the procedure is exactly
	* the same as for normal non-beam clusters, with the only exception
	* of the mass spectrum from which to draw the masses of the two
	* cluster children (see method drawChildrenMasses for details).
	*/
	tPVector fission(ClusterVector & clusters, bool softUEisOn);

	/**
	* Return the hadron spectrum
	*/
	Ptr<HadronSpectrum>::tptr spectrum() const {
	return _hadronSpectrum;
	}

	public:

	/** @name Functions used by the persistent I/O system. */
	//@{
	/**
	* Function used to write out object persistently.
	* @param os the persistent output stream written to.
	*/
	void persistentOutput(PersistentOStream & os) const;

	/**
	* Function used to read in object persistently.
	* @param is the persistent input stream read from.
	* @param version the version number of the object when written.
	*/
	void persistentInput(PersistentIStream & is, int version);
	//@}

	/**
	* Standard Init function used to initialize the interfaces.
	*/
	static void Init();

	protected:

	/** @name Clone Methods. */
	//@{
	/**
	* Make a simple clone of this object.
	* @return a pointer to the new object.
	*/
	virtual IBPtr clone() const;

	/** Make a clone of this object, possibly modifying the cloned object
	* to make it sane.
	* @return a pointer to the new object.
	*/
	virtual IBPtr fullclone() const;
	//@}

	private:

	/**
	* Private and non-existent assignment operator.
	*/
	ClusterFissioner & operator=(const ClusterFissioner &) = delete;

	/**
	* This method directs the splitting of the heavy clusters
	*
	* This method does the splitting of the clusters and all of its cluster
	* children, if heavy. All of these new children clusters are added to the
	* collection of clusters. The method works as follows.
	* Initially the vector contains just the stack of input pointers to the
	* clusters to be split. Then it will be filled recursively by all
	* of the cluster's children that are heavy enough to require
	* to be split. In each loop, the last element of the vector is
	* considered (only once because it is then removed from the vector).
	*
	* \todo is the following still true?
	* For normal, non-beam clusters, a power-like mass distribution
	* is used, whereas for beam clusters a fast-decreasing exponential mass
	* distribution is used instead. This avoids many iterative splitting which
	* could produce an unphysical large transverse energy from a supposed
	* soft beam remnant process.
	*/
	void cut(stack<ClusterPtr> &,
	ClusterVector&, tPVector & finalhadrons, bool softUEisOn);

	public:

	/**
	* Definition for easy passing of two particles.
	*/
	typedef pair<PPtr,PPtr> PPair;

	/**
	* Definition for use in the cut function.
	*/
	typedef pair<PPair,PPair> cutType;

	/**
	* Splits the input cluster.
	*
	* Split the input cluster (which can be either an heavy non-beam
	* cluster or a beam cluster). The result is two pairs of particles. The
	* first element of each pair is new cluster/hadron, while the second
	* element of each pair is the particle drawn from the vacuum to create
	* the new cluster/hadron.
	* Notice that this method treats also beam clusters by using a different
	* mass spectrum used to generate the cluster child masses (see method
	* drawChildMass).
	*/
	//@{
	/**
	* Split two-component cluster
	*/
	virtual cutType cutTwo(ClusterPtr &, tPVector & finalhadrons, bool softUEisOn);

	/**
	* Split three-component cluster
	*/
	virtual cutType cutThree(ClusterPtr &, tPVector & finalhadrons, bool softUEisOn);
	//@}
	public:

	/**
	* Produces a hadron and returns the flavour drawn from the vacuum.
	*
	* This routine produces a new hadron. It
	* also sets the momentum and vertex to the values given.
	*/
	PPair produceHadron(tcPDPtr hadron, tPPtr newPtr, const Lorentz5Momentum &a,
	const LorentzPoint &b) const;
	protected:

	/**
	* Produces a cluster from the flavours passed in.
	*
	* This routine produces a new cluster with the flavours given by ptrQ and newPtr.
	* The new 5 momentum is a and the parent momentum are c and d. C is for the
	* ptrQ and d is for the new particle newPtr. rem specifies whether the existing
	* particle is a beam remnant or not.
	*/
	PPair produceCluster(tPPtr ptrQ, tPPtr newPtr, const Lorentz5Momentum &a,
	const LorentzPoint &b, const Lorentz5Momentum &c,
	const Lorentz5Momentum &d, const bool rem,
	tPPtr spect=tPPtr(), bool remSpect=false) const;

	/**
	* Returns the new quark-antiquark pair
	* needed for fission of a heavy cluster. Equal probabilities
	* are assumed for producing u, d, or s pairs.
	*/
	void drawNewFlavour(PPtr& newPtrPos,PPtr& newPtrNeg) const;

	/**
	* Returns the new quark-antiquark pair
	* needed for fission of a heavy cluster. Equal probabilities
	* are assumed for producing u, d, or s pairs.
	* Extra argument is used when performing strangeness enhancement
	*/
	void drawNewFlavourEnhanced(PPtr& newPtrPos,PPtr& newPtrNeg, Energy2 mass2) const;


	/**
	* Produces the mass of a child cluster.
	*
	* Draw the masses \f$M'\f$ of the the cluster child produced
	* by the fission of an heavy cluster (of mass M). m1, m2 are the masses
	* of the constituents of the cluster; m is the mass of the quark extract
	* from the vacuum (together with its antiparticle). The algorithm produces
	* the mass of the cluster formed with consituent m1.
	* Two mass distributions can be used for the child cluster mass:
	* -# power-like mass distribution ("normal" mass) with power exp
	* \f[ M' = {\rm rnd}((M-m_1-m_2-m)^P, m^p)^{1/P} + m_1 \f]
	* where \f$ P \f$ is a parameter of the model and \f$ \rm{rnd} \f$ is
	* the function:
	* \f[ \rm{rnd}(a,b) = (1-r)a + r b \f]
	* and here \f$ r \f$ is a random number [0,1].
	* -# fast-decreasing exponential mass distribution ("soft" mass) with
	* rmin. rmin is given by
	* \f[ r_{\rm min} = \exp(-b (M - m_1 - m_2 - 2 m)) \f]
	* where \f$ b \f$ is a parameter of the model. The generated mass is
	* given by
	* \f[ M' = m_1 + m - \frac{\log\left(
	* {\rm rnd}(r_{\rm min}, 1-r_{\rm min})\right)}{b} \f].
	*
	* The choice of which mass distribution should be used for each of the two
	* cluster children is dictated by the parameter soft.
	*/
	Energy drawChildMass(const Energy M, const Energy m1, const Energy m2,
	const Energy m, const double exp, const bool soft) const;

	/**
	* Determine the positions of the two children clusters.
	*
	* This routine generates the momentum of the decay products. It also
	* generates the momentum in the lab frame of the partons drawn out of
	* the vacuum.
	*/
	void calculatePositions(const Lorentz5Momentum &pClu,
	const LorentzPoint & positionClu,
	const Lorentz5Momentum & pClu1,
	const Lorentz5Momentum & pClu2,
	LorentzPoint & positionClu1,
	LorentzPoint & positionClu2 ) const;

	protected:

	/**
	+ * Dimension used to calculate phase space weights
	+ */
	+ double dim() const {return _dim;}
	+
	+ /**
	* Access to soft-cluster parameter
	*/
	Energy btClM() const {return _btClM;}

	/**
	* Function that returns either the cluster mass or the lambda measure
	*/
	Energy2 clustermass(const ClusterPtr & cluster) const;

	/**
	* Draw a new flavour for the given cluster; currently defaults to
	* the default model
	*/
	virtual void drawNewFlavour(PPtr& newPtr1, PPtr& newPtr2, const ClusterPtr & cluster) const {
	if (_enhanceSProb == 0){
	drawNewFlavour(newPtr1,newPtr2);
	}
	else {
	drawNewFlavourEnhanced(newPtr1,newPtr2,clustermass(cluster));
	}
	}

	/**
	* Calculate the masses and possibly kinematics of the cluster
	* fission at hand; if claculateKineamtics is perfomring non-trivial
	* steps kinematics claulcated here will be overriden. Currentl;y resorts to the default
	*/
	virtual pair<Energy,Energy> drawNewMasses(Energy Mc, bool soft1, bool soft2,
	Lorentz5Momentum& pClu1, Lorentz5Momentum& pClu2,
	tPPtr ptrQ1, Lorentz5Momentum& pQ1,
	tPPtr, Lorentz5Momentum& pQone,
	tPPtr, Lorentz5Momentum& pQtwo,
	tPPtr ptrQ2, Lorentz5Momentum& pQ2) const {

	pair<Energy,Energy> result;

	// power for splitting
	double exp1 = !spectrum()->isExotic(ptrQ1->dataPtr()) ? _pSplitLight : _pSplitExotic;
	double exp2 = !spectrum()->isExotic(ptrQ2->dataPtr()) ? _pSplitLight : _pSplitExotic;
	for ( const long& id : spectrum()->heavyHadronizingQuarks() ) {
	assert(_pSplitHeavy.find(id) != _pSplitHeavy.end());
	if ( spectrum()->hasHeavy(id,ptrQ1->dataPtr()) ) exp1 = _pSplitHeavy.find(id)->second;
	if ( spectrum()->hasHeavy(id,ptrQ2->dataPtr()) ) exp2 = _pSplitHeavy.find(id)->second;
	}

	result.first = drawChildMass(Mc,pQ1.mass(),pQ2.mass(),pQone.mass(),exp1,soft1);
	result.second = drawChildMass(Mc,pQ2.mass(),pQ1.mass(),pQtwo.mass(),exp2,soft2);

	pClu1.setMass(result.first);
	pClu2.setMass(result.second);

	return result;

	}

	/**
	* Calculate the final kinematics of a heavy cluster decay C->C1 +
	* C2, if not already performed by drawNewMasses
	*/
	virtual void calculateKinematics(const Lorentz5Momentum &pClu,
	const Lorentz5Momentum &p0Q1,
	const bool toHadron1, const bool toHadron2,
	Lorentz5Momentum &pClu1, Lorentz5Momentum &pClu2,
	Lorentz5Momentum &pQ1, Lorentz5Momentum &pQb,
	Lorentz5Momentum &pQ2, Lorentz5Momentum &pQ2b) const;


	protected:

	/** @name Access members for child classes. */
	//@{
	/**
	* Access to the hadron selector
	*/
	HadronSpectrumPtr hadronSpectrum() const {return _hadronSpectrum;}
	//@}

	protected:

	/** @name Standard Interfaced functions. */
	//@{
	/**
	* Initialize this object after the setup phase before saving an
	* EventGenerator to disk.
	* @throws InitException if object could not be initialized properly.
	*/
	virtual void doinit();

	//@}

	private:

	/**
	* Smooth probability for dynamic threshold cuts:
	* @scale the current scale, e.g. the mass of the cluster,
	* @threshold the physical threshold,
	*/
	bool ProbablityFunction(double scale, double threshold);

	/**
	* Check if a cluster is heavy enough to split again
	*/
	bool isHeavy(tcClusterPtr );

	/**
	* Check if a cluster is heavy enough to be at least kinematically able to split
	*/
	bool canSplitMinimally(tcClusterPtr, Energy);

	/**
	* Check if can't make a hadron from the partons
	*/
	inline bool cantMakeHadron(tcPPtr p1, tcPPtr p2) {
	return ! spectrum()->canBeHadron(p1->dataPtr(), p2->dataPtr());
	}
	+
	+ /**
	+ * Claculate a veto for the phase space weight
	+ */
	+ inline bool phaseSpaceVeto(const Energy Mc, const Energy Mc1, const Energy Mc2,
	+ const Energy m, const Energy m1, const Energy m2) {
	+ double M_temp = Mc/GeV;
	+ double M1_temp = Mc1/GeV;
	+ double M2_temp = Mc2/GeV;
	+ double m_temp = m/GeV;
	+ double m1_temp = m1/GeV;
	+ double m2_temp = m2/GeV;
	+ double lam1 = sqrt((M1_temp-m1_temp-m_temp)(M1_temp-m1_temp+m_temp)(M1_temp+m1_temp+m_temp)*(M1_temp+m1_temp-m_temp));
	+ double lam2 = sqrt((M2_temp-m2_temp-m_temp)(M2_temp-m2_temp+m_temp)(M2_temp+m2_temp+m_temp)*(M2_temp+m2_temp-m_temp));
	+ double lam3 = sqrt((M_temp-M1_temp-M2_temp)(M_temp-M1_temp+M2_temp)(M_temp+M1_temp+M2_temp)*(M_temp+M1_temp-M2_temp));
	+ double ratio;
	+ double PSweight = pow(lam1lam2lam3,_dim-3.)pow(M1_tempM2_temp,2.-_dim);
	+ double overEstimate =pow(M_temp,4.*_dim-14.);
	+ ratio = PSweight/overEstimate;
	+ assert (ratio >= 0);
	+ assert (ratio <= 1);
	+ return (UseRandom::rnd()>ratio);
	+ }

	/**
	* A pointer to a Herwig::HadronSpectrum object for generating hadrons.
	*/
	HadronSpectrumPtr _hadronSpectrum;

	/**
	* @name The Cluster max mass,dependant on which quarks are involved, used to determine when
	* fission will occur.
	*/
	//@{
	Energy _clMaxLight;
	map<long,Energy> _clMaxHeavy;
	Energy _clMaxExotic;
	//@}
	/**
	* @name The power used to determine when cluster fission will occur.
	*/
	//@{
	double _clPowLight;
	map<long,double> _clPowHeavy;
	double _clPowExotic;
	//@}
	/**
	* @name The power, dependant on whic quarks are involved, used in the cluster mass generation.
	*/
	//@{
	double _pSplitLight;
	map<long,double> _pSplitHeavy;
	double _pSplitExotic;

	+ /**
	+ * Weights for alternative cluster fission
	+ */
	+ map<long,double> _fissionPwt;

	- // weights for alternaive cluster fission
	- map<long,double> _fissionPwt;
	+ /**
	+ * Include phase space weights
	+ */
	+ bool _phaseSpaceWeights;
	+
	+ /**
	+ * Dimensionality of phase space weight
	+ */
	+ double _dim;

	/**
	* Flag used to determine between normal cluster fission and alternative cluster fission
	*/
	int _fissionCluster;

	/**
	* Flag to choose static or dynamic kinematic thresholds in cluster splittings
	*/
	int _kinematicThresholdChoice;

	//@}
	/**
	* Parameter used (2/b) for the beam cluster mass generation.
	* Currently hard coded value.
	*/
	Energy _btClM;

	/**
	* Flag used to determine what distributions to use for the cluster masses.
	*/
	int _iopRem;

	/**
	* The string constant
	*/
	Tension _kappa;

	/**
	* Flag that switches between no strangeness enhancement, scaling enhancement,
	* and exponential enhancement (in numerical order)
	*/
	int _enhanceSProb;

	/**
	* Parameter that governs the strangeness enhancement scaling
	*/
	Energy _m0Fission;

	/**
	* Flag that switches between mass measures used in strangeness enhancement:
	* cluster mass, or the lambda measure - ( m_{clu}^2 - (m_q + m_{qbar})^2 )
	*/
	int _massMeasure;

	/**
	* Constant variable which stops the scale from being to large, and not worth
	* calculating
	*/
	const double _maxScale = 20.;

	/**
	* Power factor in ClausterFissioner bell probablity function
	*/
	double _probPowFactor;

	/**
	* Shifts from the center in ClausterFissioner bell probablity function
	*/
	double _probShift;

	/**
	* Shifts from the kinetic threshold in ClausterFissioner
	*/
	Energy2 _kinThresholdShift;

	};

	}

	#endif /* HERWIG_ClusterFissioner_H */

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