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	diff --git a/FixedOrderGen/include/PhaseSpacePoint.hh b/FixedOrderGen/include/PhaseSpacePoint.hh
	index 9e49a40..e244662 100644
	--- a/FixedOrderGen/include/PhaseSpacePoint.hh
	+++ b/FixedOrderGen/include/PhaseSpacePoint.hh
	@@ -1,202 +1,210 @@
	/** \file PhaseSpacePoint.hh
	* \brief Contains the PhaseSpacePoint Class
	*/

	#pragma once

	#include <bitset>
	#include <vector>

	#include "RHEJ/utility.hh"
	#include "RHEJ/Event.hh"
	#include "RHEJ/PDG_codes.hh"
	#include "RHEJ/PDF.hh"
	#include "RHEJ/RNG.hh"

	#include "Status.hh"
	#include "JetParameters.hh"
	#include "HiggsProperties.hh"

	namespace HEJFOG{
	class Process;

	using RHEJ::Particle;
	//! A point in resummation phase space
	class PhaseSpacePoint{
	public:
	//! Default PhaseSpacePoint Constructor
	PhaseSpacePoint() = default;

	//! PhaseSpacePoint Constructor
	/**
	* @param proc The process to generate
	* @param jet_def The Jet Definition Used
	* @param jetptmin Minimum Jet Transverse Momentum
	* @param rapmax Maximum parton rapidity
	* @param pdf The pdf set (used for sampling)
	* @param subl_chance Chance to turn a potentially subleading
	* emission (uno or central qqx) into an actual one
	*
	* Initially, only FKL phase space points are generated. subl_chance gives
	* the change of turning one emissions into a subleading configuration,
	* i.e. either unordered or central quark/anti-quark pair. Unordered
	* emissions require that the most extremal emission in any direction is
	* a quark or anti-quark and the next emission is a gluon. Quark/anti-quark
	* pairs are only generated for W processes. At most one subleading
	* emission will be generated in this way.
	*/
	PhaseSpacePoint(
	Process const & proc,
	JetParameters const & jet_properties,
	RHEJ::PDF & pdf, double E_beam,
	double subl_chance,
	HiggsProperties const & higgs_properties,
	RHEJ::RNG & ran
	);

	//! Get Weight Function
	/**
	* @returns Weight of Event
	*/
	double weight() const{
	return weight_;
	}

	Status status() const{
	return status_;
	}

	//! Get Incoming Function
	/**
	* @returns Incoming Particles
	*/
	std::array<Particle, 2> const & incoming() const{
	return incoming_;
	}

	//! Get Outgoing Function
	/**
	* @returns Outgoing Particles
	*/
	std::vector<Particle> const & outgoing() const{
	return outgoing_;
	}

	std::unordered_map<int, std::vector<Particle>> const & decays() const{
	return decays_;
	}

	private:
	/**
	* \internal
	* \brief Generate LO parton momentum
	*
	* @param count Number of partons to generate
	* @param is_pure_jets If true ensures momentum conservation in x and y
	* @param jet_param Jet properties to fulfil
	* @param max_pt max allowed pt for a parton (typically E_CMS)
	* @param ran Random Number Generator
	*
	* @returns Momentum of partons
	*
	* Ensures that each parton is in its own jet.
	* Generation is independent of parton flavour. Output is sorted in rapidity.
	*/
	std::vector<fastjet::PseudoJet> gen_LO_partons(
	int count, bool is_pure_jets,
	JetParameters const & jet_param,
	double max_pt,
	RHEJ::RNG & ran
	);
	Particle gen_boson(
	RHEJ::ParticleID bosonid, double mass, double width,
	RHEJ::RNG & ran
	);
	template<class ParticleMomenta>
	fastjet::PseudoJet gen_last_momentum(
	ParticleMomenta const & other_momenta,
	double mass_square, double y
	) const;

	bool jets_ok(
	std::vector<fastjet::PseudoJet> const & Born_jets,
	std::vector<fastjet::PseudoJet> const & partons
	) const;
	/**
	* \internal
	* \brief Generate incoming partons according to the PDF
	*
	* @param uf Scale used in the PDF
	*/
	void reconstruct_incoming(
	Process const & proc,
	RHEJ::PDF & pdf, double E_beam,
	double uf,
	RHEJ::RNG & ran
	);
	+ /**
	+ * @internal
	+ * @brief Returns list of all allowed initial states partons
	+ */
	+ std::array<std::bitset<11>,2> filter_partons(
	+ Process const & proc,RHEJ::RNG & ran
	+ );
	RHEJ::ParticleID generate_incoming_id(
	size_t beam_idx, double x, double uf, RHEJ::PDF & pdf,
	std::bitset<11> allowed_partons, RHEJ::RNG & ran
	);

	bool momentum_conserved(double ep) const;

	RHEJ::Particle const & most_backward_FKL(
	std::vector<RHEJ::Particle> const & partons
	) const;
	RHEJ::Particle const & most_forward_FKL(
	std::vector<RHEJ::Particle> const & partons
	) const;
	RHEJ::Particle & most_backward_FKL(std::vector<RHEJ::Particle> & partons) const;
	RHEJ::Particle & most_forward_FKL(std::vector<RHEJ::Particle> & partons) const;
	bool extremal_FKL_ok(
	std::vector<fastjet::PseudoJet> const & partons
	) const;
	double random_normal(double stddev, RHEJ::RNG & ran);
	/**
	+ * @internal
	* @brief Turns a FKL configuration into a subleading one
	*
	* @param chance Change to switch to subleading configuration
	* @param proc Process to decide which subleading
	* configurations are allowed
	*
	* With a chance of "chance" the FKL configuration is either turned into
	* a unordered configuration or, for A/W/Z bosons, a configuration with
	* a central quark/anti-quark pair.
	*/
	void maybe_turn_to_subl(double chance, Process const & proc, RHEJ::RNG & ran);
	void turn_to_uno(bool can_be_uno_backward, bool can_be_uno_forward, RHEJ::RNG & ran);
	void turn_to_qqx(RHEJ::RNG & ran);
	std::vector<Particle> decay_boson(
	RHEJ::Particle const & parent,
	std::vector<Decay> const & decays,
	RHEJ::RNG & ran
	);
	/// @brief setup outgoing partons to ensure correct coupling to boson
	void couple_boson(RHEJ::ParticleID boson, RHEJ::RNG & ran);
	Decay select_decay_channel(
	std::vector<Decay> const & decays,
	RHEJ::RNG & ran
	);
	double gen_hard_pt(
	int np, double ptmin, double ptmax, double y,
	RHEJ::RNG & ran
	);
	double gen_soft_pt(int np, double ptmax, RHEJ::RNG & ran);
	double gen_parton_pt(
	int count, JetParameters const & jet_param, double ptmax, double y,
	RHEJ::RNG & ran
	);


	double weight_;

	Status status_;

	std::array<Particle, 2> incoming_;
	std::vector<Particle> outgoing_;
	//! Particle decays in the format {outgoing index, decay products}
	std::unordered_map<int, std::vector<Particle>> decays_;
	};
	RHEJ::UnclusteredEvent to_UnclusteredEvent(PhaseSpacePoint const & psp);
	}
	diff --git a/FixedOrderGen/src/PhaseSpacePoint.cc b/FixedOrderGen/src/PhaseSpacePoint.cc
	index a5adbfc..8fba6b8 100644
	--- a/FixedOrderGen/src/PhaseSpacePoint.cc
	+++ b/FixedOrderGen/src/PhaseSpacePoint.cc
	@@ -1,650 +1,676 @@
	#include "PhaseSpacePoint.hh"

	#include <random>
	#include <algorithm>

	#include "RHEJ/Constants.hh"
	#include "RHEJ/kinematics.hh"
	#include "RHEJ/utility.hh"
	#include "RHEJ/exceptions.hh"

	#include "Process.hh"

	#include <CLHEP/Random/Randomize.h>
	#include <CLHEP/Random/RanluxEngine.h>

	using namespace RHEJ;

	namespace HEJFOG{

	static_assert(
	std::numeric_limits<double>::has_quiet_NaN,
	"no quiet NaN for double"
	);
	constexpr double NaN = std::numeric_limits<double>::quiet_NaN();
	RHEJ::UnclusteredEvent to_UnclusteredEvent(PhaseSpacePoint const & psp){
	RHEJ::UnclusteredEvent result;
	result.incoming = psp.incoming();
	std::sort(
	begin(result.incoming), end(result.incoming),
	[](Particle o1, Particle o2){return o1.p.pz()<o2.p.pz();}
	);
	assert(result.incoming.size() == 2);
	result.outgoing = psp.outgoing();
	assert(
	std::is_sorted(
	begin(result.outgoing), end(result.outgoing),
	RHEJ::rapidity_less{}
	)
	);
	assert(result.outgoing.size() >= 2);
	result.decays = psp.decays();
	result.central.mur = NaN;
	result.central.muf = NaN;
	result.central.weight = psp.weight();
	return result;
	}

	namespace{
	bool can_swap_to_uno(
	RHEJ::Particle const & p1, RHEJ::Particle const & p2
	){
	return is_parton(p1)
	&& p1.type != pid::gluon
	&& p2.type == pid::gluon;
	}

	size_t count_gluons(std::vector<Particle>::const_iterator first,
	std::vector<Particle>::const_iterator last){
	return std::count_if(first, last, [](Particle const & p)
	{return p.type == pid::gluon;});
	}

	/** assumes FKL configurations between first and last,
	* else there can be a quark in a non-extreme position
	* e.g. uno configuration gqg would pass
	*/
	bool can_change_to_qqx(
	std::vector<Particle>::const_iterator first,
	std::vector<Particle>::const_iterator last){
	return 1 < count_gluons(first,last);
	}

	bool is_AWZ_proccess(Process const & proc){
	return proc.boson && is_AWZ_boson(*proc.boson);
	}
	}

	void PhaseSpacePoint::maybe_turn_to_subl(
	double chance,
	Process const & proc,
	RHEJ::RNG & ran
	){
	if(proc.njets <= 2) return;
	assert(outgoing_.size() >= 2);

	// decide what kind of subleading process is allowed
	bool allow_uno = false;
	const size_t nout = outgoing_.size();
	const bool can_be_uno_backward = can_swap_to_uno(
	outgoing_[0], outgoing_[1]
	);
	const bool can_be_uno_forward = can_swap_to_uno(
	outgoing_[nout-1], outgoing_[nout-2]
	);
	allow_uno = can_be_uno_backward \|\| can_be_uno_forward;

	bool allow_qqx = false;
	if(is_AWZ_proccess(proc)) {
	allow_qqx = can_change_to_qqx(outgoing_.cbegin(), outgoing_.cend());
	if(incoming_[0].type == pid::gluon && incoming_[1].type == pid::gluon) {
	/// enforce qqx for initial gg
	allow_uno = false;
	chance = 1.;
	}
	}

	if(!allow_uno && !allow_qqx) return;
	if(ran.flat() < chance){
	weight_ /= chance;
	if(allow_uno && !allow_qqx){
	turn_to_uno(can_be_uno_backward, can_be_uno_forward, ran);
	} else if (!allow_uno && allow_qqx) {
	turn_to_qqx(ran);
	} else {
	assert( allow_uno && allow_qqx);
	if(ran.flat() < 0.5) turn_to_uno(can_be_uno_backward, can_be_uno_forward, ran);
	else turn_to_qqx(ran);
	weight_ *= 2.;
	}
	} else weight_ /= 1 - chance;

	}

	void PhaseSpacePoint::turn_to_uno(
	const bool can_be_uno_backward, const bool can_be_uno_forward,
	RHEJ::RNG & ran
	){
	if(!can_be_uno_backward && !can_be_uno_forward) return;
	const size_t nout = outgoing_.size();
	if(can_be_uno_backward && can_be_uno_forward){
	if(ran.flat() < 0.5){
	std::swap(outgoing_[0].type, outgoing_[1].type);
	} else {
	std::swap(outgoing_[nout-1].type, outgoing_[nout-2].type);
	}
	weight_ *= 2.;
	} else if(can_be_uno_backward){
	std::swap(outgoing_[0].type, outgoing_[1].type);
	} else {
	assert(can_be_uno_forward);
	std::swap(outgoing_[nout-1].type, outgoing_[nout-2].type);
	}
	}

	void PhaseSpacePoint::turn_to_qqx(RHEJ::RNG & ran){
	/// find first and last gluon in FKL chain
	auto first = std::find_if(outgoing_.begin(), outgoing_.end(),
	[](Particle const & p){return p.type == pid::gluon;});
	std::vector<Particle*> FKL_gluons;
	for(auto p = first; p<outgoing_.end(); ++p){
	if((p).type == pid::gluon) FKL_gluons.push_back(&p);
	else if(is_quark(p) \|\| is_antiquark(p)) break;
	}
	const size_t ng = FKL_gluons.size();
	if(ng < 2)
	throw std::logic_error("not enough gluons to create qqx");
	// select flavour of quark
	const double r1 = 2.*ran.flat()-1.;
	weight_ = n_f2;
	int flavour = pid::down;
	for (double sum = 1./n_f; sum < std::abs(r1); sum += 1./n_f)
	++flavour;
	flavour*=r1<0.?-1:1;
	// select gluon for switch
	const size_t idx = floor((ng-1) * ran.flat());
	weight_ *= (ng-1);
	FKL_gluons[idx]->type = ParticleID(flavour);
	FKL_gluons[idx+1]->type = ParticleID(-flavour);
	}

	template<class ParticleMomenta>
	fastjet::PseudoJet PhaseSpacePoint::gen_last_momentum(
	ParticleMomenta const & other_momenta,
	const double mass_square, const double y
	) const {
	std::array<double,2> pt{0.,0.};
	for (auto const & p: other_momenta) {
	pt[0]-= p.px();
	pt[1]-= p.py();
	}

	const double mperp = sqrt(pt[0]pt[0]+pt[1]pt[1]+mass_square);
	const double pz=mperp*sinh(y);
	const double E=mperp*cosh(y);

	return {pt[0], pt[1], pz, E};
	}

	PhaseSpacePoint::PhaseSpacePoint(
	Process const & proc,
	JetParameters const & jet_param,
	RHEJ::PDF & pdf, double E_beam,
	double subl_chance,
	HiggsProperties const & h,
	RHEJ::RNG & ran
	)
	{
	assert(proc.njets >= 2);
	status_ = good;
	weight_ = 1;

	const int nout = proc.njets + (proc.boson?1:0);
	outgoing_.reserve(nout);

	// generate parton momenta
	const bool is_pure_jets = !proc.boson;
	auto partons = gen_LO_partons(
	proc.njets, is_pure_jets, jet_param, E_beam, ran
	);
	// pre fill flavour with gluons
	for(auto&& p_out: partons) {
	outgoing_.emplace_back(Particle{pid::gluon, std::move(p_out)});
	}
	if(status_ != good) return;

	if(proc.boson){
	switch (*proc.boson) {
	case pid::Higgs:{
	auto Hparticle=gen_boson(pid::higgs, h.mass, h.width, ran);
	auto pos=std::upper_bound(
	begin(outgoing_),end(outgoing_),Hparticle,rapidity_less{}
	);
	outgoing_.insert(pos, Hparticle);
	if(! h.decays.empty()){
	const int boson_idx = std::distance(begin(outgoing_), pos);
	decays_.emplace(
	boson_idx,
	decay_boson(outgoing_[boson_idx], h.decays, ran)
	);
	}
	break;
	}
	case pid::Wp:{
	/// @TODO change label names, currently this is just a relabel Higgs
	auto Hparticle=gen_boson(pid::Wp, h.mass, h.width, ran);
	auto pos=std::upper_bound(
	begin(outgoing_),end(outgoing_),Hparticle,rapidity_less{}
	);
	outgoing_.insert(pos, Hparticle);
	if(! h.decays.empty()){
	const int boson_idx = std::distance(begin(outgoing_), pos);
	decays_.emplace(
	boson_idx,
	decay_boson(outgoing_[boson_idx], h.decays, ran)
	);
	}
	break;
	}
	case pid::Wm:{
	/// @TODO change label names, currently this is just a relabel Higgs
	auto Hparticle=gen_boson(pid::Wm, h.mass, h.width, ran);
	auto pos=std::upper_bound(
	begin(outgoing_),end(outgoing_),Hparticle,rapidity_less{}
	);
	outgoing_.insert(pos, Hparticle);
	if(! h.decays.empty()){
	const int boson_idx = std::distance(begin(outgoing_), pos);
	decays_.emplace(
	boson_idx,
	decay_boson(outgoing_[boson_idx], h.decays, ran)
	);
	}
	break;
	}
	case pid::photon:
	case pid::Z:
	default:
	throw std::logic_error("Emission of boson of unsupported type");
	}
	}
	// normalisation of momentum-conserving delta function
	weight_ = pow(2M_PI, 4);

	reconstruct_incoming(proc, pdf, E_beam, jet_param.min_pt, ran);
	if(status_ != good) return;
	// set outgoing states
	most_backward_FKL(outgoing_).type = incoming_[0].type;
	most_forward_FKL(outgoing_).type = incoming_[1].type;

	maybe_turn_to_subl(subl_chance, proc, ran);

	if(proc.boson) couple_boson(*proc.boson, ran);
	}

	double PhaseSpacePoint::gen_hard_pt(
	int np , double ptmin, double ptmax, double y,
	RHEJ::RNG & ran
	) {
	// heuristic parameters for pt sampling
	const double ptpar = ptmin + np/5.;
	const double arg_small_y = atan((ptmax - ptmin)/ptpar);
	const double y_cut = 3.;

	const double r1 = ran.flat();
	if(y < y_cut){
	const double pt = ptmin + ptpartan(r1arg_small_y);
	const double temp = cos(r1*arg_small_y);
	weight_ = ptptpararg_small_y/(temptemp);
	return pt;
	}

	const double ptpar2 = ptpar/(1 + 5*(y-y_cut));
	const double temp = 1. - std::exp((ptmin-ptmax)/ptpar2);
	const double pt = ptmin - ptpar2std::log(1-r1temp);
	weight_ = ptptpar2temp/(1-r1temp);
	return pt;
	}

	double PhaseSpacePoint::gen_soft_pt(int np, double max_pt, RHEJ::RNG & ran) {
	constexpr double ptpar = 4.;

	const double r = ran.flat();
	const double pt = max_pt + ptpar/np*std::log(r);
	weight_ = ptptpar/(np*r);
	return pt;
	}

	double PhaseSpacePoint::gen_parton_pt(
	int count, JetParameters const & jet_param, double max_pt, double y,
	RHEJ::RNG & ran
	) {
	constexpr double p_small_pt = 0.02;

	if(! jet_param.peak_pt) {
	return gen_hard_pt(count, jet_param.min_pt, max_pt, y, ran);
	}
	const double r = ran.flat();
	if(r > p_small_pt) {
	weight_ /= 1. - p_small_pt;
	return gen_hard_pt(count, *jet_param.peak_pt, max_pt, y, ran);
	}
	weight_ /= p_small_pt;
	const double pt = gen_soft_pt(count, *jet_param.peak_pt, ran);
	if(pt < jet_param.min_pt) {
	weight_=0.0;
	status_ = not_enough_jets;
	return jet_param.min_pt;
	}
	return pt;
	}

	std::vector<fastjet::PseudoJet> PhaseSpacePoint::gen_LO_partons(
	int np, bool is_pure_jets,
	JetParameters const & jet_param,
	double max_pt,
	RHEJ::RNG & ran
	){
	if (np<2) throw std::invalid_argument{"Not enough partons in gen_LO_partons"};

	weight_ /= pow(16.*pow(M_PI,3),np);
	weight_ /= std::tgamma(np+1); //remove rapidity ordering
	std::vector<fastjet::PseudoJet> partons;
	partons.reserve(np);
	for(int i = 0; i < np; ++i){
	const double y = -jet_param.max_y + 2jet_param.max_yran.flat();
	weight_ = 2jet_param.max_y;

	const bool is_last_parton = i+1 == np;
	if(is_pure_jets && is_last_parton) {
	constexpr double parton_mass_sq = 0.;
	partons.emplace_back(gen_last_momentum(partons, parton_mass_sq, y));
	break;
	}

	const double phi = 2M_PIran.flat();
	weight_ = 2.0M_PI;

	const double pt = gen_parton_pt(np, jet_param, max_pt, y, ran);
	if(weight_ == 0.0) return {};

	partons.emplace_back(fastjet::PtYPhiM(pt, y, phi));
	assert(jet_param.min_pt <= partons[i].pt());
	assert(partons[i].pt() <= max_pt+1e-5);
	}
	// Need to check that at LO, the number of jets = number of partons;
	fastjet::ClusterSequence cs(partons, jet_param.def);
	auto cluster_jets=cs.inclusive_jets(jet_param.min_pt);
	if (cluster_jets.size()!=unsigned(np)){
	weight_=0.0;
	status_ = not_enough_jets;
	return {};
	}

	std::sort(begin(partons), end(partons), rapidity_less{});

	return partons;
	}

	Particle PhaseSpacePoint::gen_boson(
	RHEJ::ParticleID bosonid, double mass, double width,
	RHEJ::RNG & ran
	){
	// Usual phase space measure
	weight_ /= 16.*pow(M_PI, 3);

	// Generate a y Gaussian distributed around 0
	/// @TODO: magic number only for Higgs
	/// @TODO better sampling for W
	const double y = random_normal(1.6, ran);
	const double r1 = ran.flat();
	const double sH = mass*(
	mass + widthtan(M_PI/2.r1 + (r1-1.)*atan(mass/width))
	);

	auto p = gen_last_momentum(outgoing_, sH, y);

	return Particle{bosonid, std::move(p)};
	}

	Particle const & PhaseSpacePoint::most_backward_FKL(
	std::vector<Particle> const & partons
	) const{
	if(!RHEJ::is_parton(partons[0])) return partons[1];
	return partons[0];
	}

	Particle const & PhaseSpacePoint::most_forward_FKL(
	std::vector<Particle> const & partons
	) const{
	const size_t last_idx = partons.size() - 1;
	if(!RHEJ::is_parton(partons[last_idx])) return partons[last_idx-1];
	return partons[last_idx];
	}

	Particle & PhaseSpacePoint::most_backward_FKL(
	std::vector<Particle> & partons
	) const{
	if(!RHEJ::is_parton(partons[0])) return partons[1];
	return partons[0];
	}

	Particle & PhaseSpacePoint::most_forward_FKL(
	std::vector<Particle> & partons
	) const{
	const size_t last_idx = partons.size() - 1;
	if(!RHEJ::is_parton(partons[last_idx])) return partons[last_idx-1];
	return partons[last_idx];
	}

	namespace {
	/// partons are ordered: even = anti, 0 = gluon
	ParticleID index_to_pid(size_t i){
	if(!i) return pid::gluon;
	return static_cast<ParticleID>(i%2?(i+1)/2:-i/2);
	}

	+ /// partons are ordered: even = anti, 0 = gluon
	+ size_t pid_to_index(ParticleID id){
	+ if(id==pid::gluon) return 0;
	+ return id>0?id2-1:abs(id)2;
	+ }
	+
	+ std::bitset<11> init_allowed(ParticleID const id){
	+ if(abs(id) == pid::proton)
	+ return ~0;
	+ std::bitset<11> out = 0;
	+ if(is_parton(id))
	+ out[pid_to_index(id)] = 1;
	+ return out;
	+ }
	+
	/// decides which "index" (see index_to_pid) are allowed for process
	- std::bitset<11> switch_allowed(Process const & proc){
	+ std::bitset<11> allowed_quarks(ParticleID const boson){
	std::bitset<11> allowed = ~0;
	- allowed[0] = 0; // no gluon
	- if(abs(*proc.boson) == pid::Wp){
	- // special case W+2j:
	- // Wp: anti-down or up-type quark, no b/t -> 0001100110(0) = 204
	- // Wm: down or anti-up-type quark, no b/t -> 0010011001(0) = 306
	- allowed &= (*proc.boson)>0?204:306;
	+ if(abs(boson) == pid::Wp){
	+ // special case W:
	+ // Wp: anti-down or up-type quark, no b/t -> 0001100110(1) = 205
	+ // Wm: down or anti-up-type quark, no b/t -> 0010011001(1) = 307
	+ allowed = boson>0?205:307;
	}
	return allowed;
	}
	}

	+ std::array<std::bitset<11>,2> PhaseSpacePoint::filter_partons(
	+ Process const & proc, RHEJ::RNG & ran
	+ ){
	+ std::array<std::bitset<11>,2> allowed_partons{
	+ init_allowed(proc.incoming[0]),
	+ init_allowed(proc.incoming[1])
	+ };
	+ // special case A/W/Z + 2/3 jets
	+ if(is_AWZ_proccess(proc) && (proc.njets < 4)){
	+ auto allowed(allowed_quarks(*proc.boson));
	+ if(proc.njets == 2) allowed[0]=0; // no initial gluon for 2j
	+ std::array<std::bitset<11>,2> const maybe_partons{
	+ allowed_partons[0]&allowed, allowed_partons[1]&allowed};
	+
	+ if(maybe_partons[0].any() && maybe_partons[1].any()){
	+ // two options to get allowed initial state => choose one at random
	+ const size_t idx = ran.flat() < 0.5;
	+ allowed_partons[idx] = maybe_partons[idx];
	+ } else if(maybe_partons[0].any()) {
	+ // only first possible => choose
	+ allowed_partons[0] = maybe_partons[0];
	+ } else if(maybe_partons[1].any()) {
	+ // only second possible => choose
	+ allowed_partons[1] = maybe_partons[1];
	+ } else{
	+ throw std::invalid_argument{"Incoming state not allowed."};
	+ }
	+ }
	+ return allowed_partons;
	+ }
	+
	void PhaseSpacePoint::reconstruct_incoming(
	Process const & proc,
	RHEJ::PDF & pdf, double E_beam,
	double uf,
	RHEJ::RNG & ran
	){
	std::tie(incoming_[0].p, incoming_[1].p) = incoming_momenta(outgoing_);
	// calculate xa, xb
	const double sqrts=2*E_beam;
	const double xa=(incoming_[0].p.e()-incoming_[0].p.pz())/sqrts;
	const double xb=(incoming_[1].p.e()+incoming_[1].p.pz())/sqrts;
	// abort if phase space point is outside of collider energy reach
	if (xa>1. \|\| xb>1.){
	weight_=0;
	status_ = too_much_energy;
	return;
	}
	// pick pdfs
	/** @TODO
	* ufa, ufb don't correspond to our final scale choice.
	* The reversed HEJ scale generators currently expect a full event as input,
	* so fixing this is not completely trivial
	*/
	auto const & ids = proc.incoming;
	- std::array<std::bitset<11>,2> allowed_partons{~0,~0};
	- // special case A/W/Z+2j: needs one quark initially
	- if(proc.njets == 2 && is_AWZ_proccess(proc)){
	- // @TODO optimise: do not allow dd initial for Wp, also for 3j
	- if(ids[0] != pid::gluon && ids[1] != pid::gluon){
	- // both can be quarks => force one to be a gluon
	- weight_*=2.;
	- allowed_partons[ran.flat() < 0.5] = switch_allowed(proc);
	- } else if(ids[0] == pid::gluon) {
	- if(ids[1] == pid::gluon) {
	- throw RHEJ::not_implemented{
	- "W+2 jet process requires at least one initial quark"
	- };
	- }
	- // first gluon -> second has to be quark
	- allowed_partons[1] = switch_allowed(proc);
	- } else {
	- // second gluon -> first has to be quark
	- allowed_partons[0] = switch_allowed(proc);
	- }
	- }
	+ std::array<std::bitset<11>,2> allowed_partons(filter_partons(proc, ran));
	for(size_t i = 0; i < 2; ++i){
	if(ids[i] == pid::proton \|\| ids[i] == pid::p_bar){
	incoming_[i].type =
	generate_incoming_id(i, i?xb:xa, uf, pdf, allowed_partons[i], ran);
	} else {
	+ assert(allowed_partons[i][pid_to_index(ids[i])]);
	incoming_[i].type = ids[i];
	}
	}
	assert(momentum_conserved(1e-7));
	}

	RHEJ::ParticleID PhaseSpacePoint::generate_incoming_id(
	size_t const beam_idx, double const x, double const uf,
	RHEJ::PDF & pdf, std::bitset<11> allowed_partons, RHEJ::RNG & ran
	){
	std::array<double,11> pdf_wt;
	pdf_wt[0] = allowed_partons[0]?fabs(pdf.pdfpt(beam_idx,x,uf,pid::gluon)):0.;
	double pdftot = pdf_wt[0];
	for(size_t i = 1; i < pdf_wt.size(); ++i){
	pdf_wt[i] = allowed_partons[i]?4./9.*fabs(pdf.pdfpt(beam_idx,x,uf,index_to_pid(i))):0;
	pdftot += pdf_wt[i];
	}
	const double r1 = pdftot * ran.flat();
	double sum = 0;
	for(size_t i=0; i < pdf_wt.size(); ++i){
	if (r1 < (sum+=pdf_wt[i])){
	weight_*= pdftot/pdf_wt[i];
	return index_to_pid(i);
	}
	}
	std::cerr << "Error in choosing incoming parton: "<<x<<" "<<uf<<" "
	<<sum<<" "<<pdftot<<" "<<r1<<std::endl;
	throw std::logic_error{"Failed to choose parton flavour"};
	}

	namespace {
	bool is_up_type(Particle const & part){
	return RHEJ::is_anyquark(part) && !(abs(part.type)%2);
	}
	bool is_down_type(Particle const & part){
	return RHEJ::is_anyquark(part) && abs(part.type)%2;
	}
	}

	void PhaseSpacePoint::couple_boson(
	RHEJ::ParticleID const boson, RHEJ::RNG & ran
	){
	if(abs(boson) != pid::Wp) return; // only matters for W

	// find all possible quarks
	const int sign_W = boson>0?1:-1;
	std::vector<Particle*> allowed_parts;
	for(auto & part: outgoing_){
	// Wp -> up OR anti-down, Wm -> anti-up OR down, no bottom
	if ( abs(part.type)<5
	&& ( (sign_W*part.type > 0 && is_up_type(part))
	\|\| (sign_W*part.type < 0 && is_down_type(part)) ) )
	allowed_parts.push_back(&part);
	}
	if(!allowed_parts.size()){
	/// @TODO do not allow such states in the generation
	status_=wrong_final_state;
	return;
	}

	// select one and flip it
	size_t idx = 0;
	if(allowed_parts.size() > 1){
	/// @TODO more efficient sampling
	/// old code: probability[i] = exp(parton[i].y - W.y)
	idx = floor(ran.flat()*allowed_parts.size());
	weight_ *= allowed_parts.size();
	}
	allowed_parts[idx]->type =
	static_cast<ParticleID>( allowed_parts[idx]->type - sign_W );
	}

	double PhaseSpacePoint::random_normal(
	double stddev,
	RHEJ::RNG & ran
	){
	const double r1 = ran.flat();
	const double r2 = ran.flat();
	const double lninvr1 = -log(r1);
	const double result = stddevsqrt(2.lninvr1)cos(2.M_PI*r2);
	weight_ = exp(resultresult/(2stddevstddev))sqrt(2.M_PI)*stddev;
	return result;
	}

	bool PhaseSpacePoint::momentum_conserved(double ep) const{
	fastjet::PseudoJet diff;
	for(auto const & in: incoming()) diff += in.p;
	for(auto const & out: outgoing()) diff -= out.p;
	return nearby_ep(diff, fastjet::PseudoJet{}, ep);
	}

	Decay PhaseSpacePoint::select_decay_channel(
	std::vector<Decay> const & decays,
	RHEJ::RNG & ran
	){
	double br_total = 0.;
	for(auto const & decay: decays) br_total += decay.branching_ratio;
	// adjust weight
	// this is given by (channel branching ratio)/(chance to pick channel)
	// where (chance to pick channel) =
	// (channel branching ratio)/(total branching ratio)
	weight_ *= br_total;
	const double r1 = br_total*ran.flat();
	double br_sum = 0.;
	for(auto const & decay: decays){
	br_sum += decay.branching_ratio;
	if(r1 < br_sum) return decay;
	}
	throw std::logic_error{"unreachable"};
	}

	std::vector<Particle> PhaseSpacePoint::decay_boson(
	RHEJ::Particle const & parent,
	std::vector<Decay> const & decays,
	RHEJ::RNG & ran
	){
	const auto channel = select_decay_channel(decays, ran);
	if(channel.products.size() != 2){
	throw RHEJ::not_implemented{
	"only decays into two particles are implemented"
	};
	}
	std::vector<Particle> decay_products(channel.products.size());
	for(size_t i = 0; i < channel.products.size(); ++i){
	decay_products[i].type = channel.products[i];
	}
	// choose polar and azimuth angle in parent rest frame
	const double E = parent.m()/2;
	const double theta = 2.M_PIran.flat();
	const double cos_phi = 2.*ran.flat()-1.;
	const double sin_phi = sqrt(1. - cos_phi*cos_phi); // Know 0 < phi < pi
	const double px = Ecos(theta)sin_phi;
	const double py = Esin(theta)sin_phi;
	const double pz = E*cos_phi;
	decay_products[0].p.reset(px, py, pz, E);
	decay_products[1].p.reset(-px, -py, -pz, E);
	for(auto & particle: decay_products) particle.p.boost(parent.p);
	return decay_products;
	}
	}

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