diff --git a/src/PhaseSpacePoint.cc b/src/PhaseSpacePoint.cc
index 9ea93fa..f1c5fd1 100644
--- a/src/PhaseSpacePoint.cc
+++ b/src/PhaseSpacePoint.cc
@@ -1,631 +1,637 @@
 /**
  *  \authors   Jeppe Andersen, Tuomas Hapola, Marian Heil, Andreas Maier, Jennifer Smillie
  *  \date      2019
  *  \copyright GPLv2 or later
  */
 #include "HEJ/PhaseSpacePoint.hh"
 
 #include <algorithm>
 #include <assert.h>
 #include <numeric>
 #include <random>
 
 #include "fastjet/ClusterSequence.hh"
 
 #include "HEJ/Constants.hh"
 #include "HEJ/Event.hh"
 #include "HEJ/JetSplitter.hh"
 #include "HEJ/kinematics.hh"
 #include "HEJ/resummation_jet.hh"
 #include "HEJ/utility.hh"
 #include "HEJ/PDG_codes.hh"
 #include "HEJ/event_types.hh"
 
 namespace HEJ{
   namespace {
     constexpr int max_jet_user_idx = PhaseSpacePoint::ng_max;
 
     bool is_nonjet_parton(fastjet::PseudoJet const & parton){
       assert(parton.user_index() != -1);
       return parton.user_index() > max_jet_user_idx;
     }
 
     bool is_jet_parton(fastjet::PseudoJet const & parton){
       assert(parton.user_index() != -1);
       return parton.user_index() <= max_jet_user_idx;
     }
 
     // user indices for partons with extremal rapidity
     constexpr int qqxb_idx = -7;
     constexpr int qqxf_idx = -6;
     constexpr int unob_idx = -5;
     constexpr int unof_idx = -4;
     constexpr int backward_FKL_idx = -3;
     constexpr int forward_FKL_idx = -2;
   }
 
   namespace {
     double estimate_ng_mean(std::vector<fastjet::PseudoJet> const & Born_jets){
       const double delta_y =
         Born_jets.back().rapidity() - Born_jets.front().rapidity();
       assert(delta_y > 0);
       // Formula derived from fit in arXiv:1805.04446 (see Fig. 2)
       return 0.975052*delta_y;
     }
   }
 
   std::vector<fastjet::PseudoJet> PhaseSpacePoint::cluster_jets(
       std::vector<fastjet::PseudoJet> const & partons
   ) const{
     fastjet::ClusterSequence cs(partons, param_.jet_param.def);
     return cs.inclusive_jets(param_.jet_param.min_pt);
   }
 
   bool PhaseSpacePoint::pass_resummation_cuts(
       std::vector<fastjet::PseudoJet> const & jets
   ) const{
     return cluster_jets(jets).size() == jets.size();
   }
 
   int PhaseSpacePoint::sample_ng(std::vector<fastjet::PseudoJet> const & Born_jets){
     const double ng_mean = estimate_ng_mean(Born_jets);
     std::poisson_distribution<int> dist(ng_mean);
     const int ng = dist(ran_.get());
     assert(ng >= 0);
     assert(ng < ng_max);
     weight_ *= std::tgamma(ng + 1)*std::exp(ng_mean)*std::pow(ng_mean, -ng);
     return ng;
   }
 
   void PhaseSpacePoint::copy_AWZH_boson_from(Event const & event){
     auto const & from = event.outgoing();
 
     const auto AWZH_boson = std::find_if(
         begin(from), end(from),
         [](Particle const & p){ return is_AWZH_boson(p); }
     );
     if(AWZH_boson == end(from)) return;
     auto insertion_point = std::lower_bound(
         begin(outgoing_), end(outgoing_), *AWZH_boson, rapidity_less{}
     );
     outgoing_.insert(insertion_point, *AWZH_boson);
 
     // copy decay products
     const int idx = std::distance(begin(from), AWZH_boson);
     assert(idx >= 0);
     const auto decay_it = event.decays().find(idx);
     if(decay_it != end(event.decays())){
       const int new_idx = std::distance(begin(outgoing_), insertion_point);
       assert(new_idx >= 0);
       assert(outgoing_[new_idx].type == AWZH_boson->type);
       decays_.emplace(new_idx, decay_it->second);
     }
 
     assert(std::is_sorted(begin(outgoing_), end(outgoing_), rapidity_less{}));
   }
 
 
   //! \brief relabels qqx-pair with its PDG IDs.
   //*@param ev               Born Event
   //
   // This function will label the qqx pair in a qqx event back to
   // their original types from the input event.
   void PhaseSpacePoint::label_qqx(Event const & event){
     auto const & bornout = event.outgoing();
+    bool Wstart = (abs(bornout[0].type)==pid::Wp);
     const auto backquark = std::find_if(
-        begin(bornout) + 1 - ((qqxb_)?1:0), end(bornout) - 1 + ((qqxf_)?1:0) ,
+      begin(bornout) + 1 + ((Wstart)?1:0) - ((qqxb_)?1:0), end(bornout) - 1 + ((qqxf_)?1:0) ,
         [](Particle const & s){ return (is_anyquark(s.type)); }
     );
     if(backquark == end(bornout) || (backquark+1)->type==pid::gluon) weight_= 0;
 
     auto quark1type = backquark->type;
     auto quark2type = (backquark+1)->type;
 
     if(is_AWZ_boson((backquark+1)->type)) quark2type = (backquark+2)->type;
 
     if( !((is_quark(quark1type) && is_antiquark(quark2type))
           && !(is_quark(quark2type) && is_antiquark(quark1type)))
       ){
       weight_=0;
     }
 
     auto partons = to_PseudoJet(filter_partons(outgoing_));
     fastjet::ClusterSequence cs(partons, event.jet_def());
     const auto jets = fastjet::sorted_by_rapidity(cs.inclusive_jets(event.min_jet_pt()));
 
     const auto indices = cs.particle_jet_indices({jets});
     assert(partons.size() == indices.size());
 
     int qpart=-1;
     // Find Parton in res event closest to most backward qqx jet in born
     for (size_t i=0; i<indices.size(); i++) {
       if( (indices[i] != -1) && (indices[i]==indices[i+1]-1)
           && nearby_ep(backquark->rapidity(), partons[i].rapidity(), 0.1)){
         qpart=i;
         outgoing_.at(qpart).type = quark1type;
         outgoing_.at(qpart+1).type = quark2type;
         break;
       }
     }
-
     if(qpart==-1) weight_=0;
     assert(std::is_sorted(begin(outgoing_), end(outgoing_), rapidity_less{}));
   }
 
   PhaseSpacePoint::PhaseSpacePoint(
       Event const & ev, PhaseSpacePointConfig conf, HEJ::RNG & ran
   ):
     unob_{ev.type() == event_type::unob},
     unof_{ev.type() == event_type::unof},
     qqxb_{ev.type() == event_type::qqxexb},
     qqxf_{ev.type() == event_type::qqxexf},
     qqxmid_{ev.type() == event_type::qqxmid},
     param_{std::move(conf)},
     ran_{ran}
   {
     weight_ = 1;
     const auto Born_jets = sorted_by_rapidity(ev.jets());
     const int ng = sample_ng(Born_jets);
     weight_ /= std::tgamma(ng + 1);
     const int ng_jets = sample_ng_jets(ng, Born_jets);
     std::vector<fastjet::PseudoJet> out_partons = gen_non_jet(
        ng - ng_jets, CMINPT, param_.jet_param.min_pt
     );
 
       const auto qperp = std::accumulate(
         begin(out_partons), end(out_partons),
         fastjet::PseudoJet{}
       );
       const auto jets = reshuffle(Born_jets, qperp);
       if(weight_ == 0.) return;
       if(! pass_resummation_cuts(jets)){
        weight_ = 0.;
        return;
       }
       std::vector<fastjet::PseudoJet> jet_partons = split(jets, ng_jets);
       if(weight_ == 0.) return;
       rescale_rapidities(
         out_partons,
         most_backward_FKL(jet_partons).rapidity(),
         most_forward_FKL(jet_partons).rapidity()
       );
       if(! cluster_jets(out_partons).empty()){
         weight_ = 0.;
         return;
       }
       std::sort(begin(out_partons), end(out_partons), rapidity_less{});
       assert(
         std::is_sorted(begin(jet_partons), end(jet_partons), rapidity_less{})
       );
       const auto first_jet_parton = out_partons.insert(
         end(out_partons), begin(jet_partons), end(jet_partons)
       );
       std::inplace_merge(
         begin(out_partons), first_jet_parton, end(out_partons), rapidity_less{}
       );
 
     if(! jets_ok(Born_jets, out_partons)){
       weight_ = 0.;
       return;
     }
     weight_ *= phase_space_normalisation(Born_jets.size(), out_partons.size());
 
     outgoing_.reserve(out_partons.size() + 1); // one slot for possible A, W, Z, H
     for(auto & p: out_partons){
       outgoing_.emplace_back(Particle{pid::gluon, std::move(p), {}});
     }
 
     const auto WEmit = std::find_if(
       begin(ev.outgoing()), end(ev.outgoing()),
       [](Particle const & s){ return abs(s.type) == pid::Wp; }
     );
 
     if (WEmit != end(ev.outgoing())){
       if(!qqxb_)
         outgoing_[unob_].type = filter_partons(ev.outgoing())[unob_].type;
       if(!qqxf_)
         outgoing_.rbegin()[unof_].type = filter_partons(ev.outgoing()).rbegin()[unof_].type;
     }
     else{
       most_backward_FKL(outgoing_).type = ev.incoming().front().type;
       most_forward_FKL(outgoing_).type = ev.incoming().back().type;
     }
 
     if(qqxmid_||qqxb_||qqxf_){
       label_qqx(ev);
     }
+
+    if(! jets_ok(Born_jets, out_partons)){
+      weight_ = 0.;
+      return;
+    }
+
     copy_AWZH_boson_from(ev);
 
     assert(!outgoing_.empty());
 
     reconstruct_incoming(ev.incoming());
   }
 
   std::vector<fastjet::PseudoJet> PhaseSpacePoint::gen_non_jet(
       int count, double ptmin, double ptmax
   ){
     // heuristic parameters for pt sampling
     const double ptpar = 1.3 + count/5.;
     const double temp1 = atan((ptmax - ptmin)/ptpar);
 
     std::vector<fastjet::PseudoJet> partons(count);
     for(size_t i = 0; i < (size_t) count; ++i){
       const double r1 = ran_.get().flat();
       const double pt = ptmin + ptpar*tan(r1*temp1);
       const double temp2 = cos(r1*temp1);
       const double phi = 2*M_PI*ran_.get().flat();
       weight_ *= 2.0*M_PI*pt*ptpar*temp1/(temp2*temp2);
       // we don't know the allowed rapidity span yet,
       // set a random value to be rescaled later on
       const double y = ran_.get().flat();
       partons[i].reset_PtYPhiM(pt, y, phi);
       // Set user index higher than any jet-parton index
       // in order to assert that these are not inside jets
       partons[i].set_user_index(i + 1 + ng_max);
 
       assert(ptmin-1e-5 <= partons[i].pt() && partons[i].pt() <= ptmax+1e-5);
     }
     assert(std::all_of(partons.cbegin(), partons.cend(), is_nonjet_parton));
     return partons;
   }
 
   void PhaseSpacePoint::rescale_rapidities(
       std::vector<fastjet::PseudoJet> & partons,
       double ymin, double ymax
   ){
     constexpr double ep = 1e-7;
     for(auto & parton: partons){
       assert(0 <= parton.rapidity() && parton.rapidity() <= 1);
       const double dy = ymax - ymin - 2*ep;
       const double y = ymin + ep + dy*parton.rapidity();
       parton.reset_momentum_PtYPhiM(parton.pt(), y, parton.phi());
       weight_ *= dy;
       assert(ymin <= parton.rapidity() && parton.rapidity() <= ymax);
     }
   }
 
   namespace {
     template<typename T, typename... Rest>
     auto min(T const & a, T const & b, Rest&&... r) {
       using std::min;
       return min(a, min(b, std::forward<Rest>(r)...));
     }
   }
 
   double PhaseSpacePoint::probability_in_jet(
       std::vector<fastjet::PseudoJet> const & Born_jets
   ) const{
     assert(std::is_sorted(begin(Born_jets), end(Born_jets), rapidity_less{}));
     assert(Born_jets.size() >= 2);
 
     const double dy =
       Born_jets.back().rapidity() - Born_jets.front().rapidity();
     const double R = param_.jet_param.def.R();
     const int njets = Born_jets.size();
     const double p_J_y_large = (njets-1)*R*R/(2.*dy);
     const double p_J_y0 = njets*R/M_PI;
     return min(p_J_y_large, p_J_y0, 1.);
   }
 
   int PhaseSpacePoint::sample_ng_jets(
       int ng, std::vector<fastjet::PseudoJet> const & Born_jets
   ){
     const double p_J = probability_in_jet(Born_jets);
     std::binomial_distribution<> bin_dist(ng, p_J);
     const int ng_J = bin_dist(ran_.get());
     weight_ *= std::pow(p_J, -ng_J)*std::pow(1 - p_J, ng_J - ng);
     return ng_J;
   }
 
   std::vector<fastjet::PseudoJet> PhaseSpacePoint::reshuffle(
       std::vector<fastjet::PseudoJet> const & Born_jets,
       fastjet::PseudoJet const & q
   ){
     if(q == fastjet::PseudoJet{0, 0, 0, 0}) return Born_jets;
     const auto jets = resummation_jet_momenta(Born_jets, q);
     if(jets.empty()){
       weight_ = 0;
       return {};
     }
 
     // additional Jacobian to ensure Born integration over delta gives 1
     weight_ *= resummation_jet_weight(Born_jets, q);
     return jets;
   }
 
   std::vector<int> PhaseSpacePoint::distribute_jet_partons(
       int ng_jets, std::vector<fastjet::PseudoJet> const & jets
   ){
     size_t first_valid_jet = 0;
     size_t num_valid_jets = jets.size();
     const double R_eff = 5./3.*param_.jet_param.def.R();
     // if there is an unordered jet too far away from the FKL jets
     // then extra gluon constituents of the unordered jet would
     // violate the FKL rapidity ordering
     if((unob_||qqxb_) && jets[0].delta_R(jets[1]) > R_eff){
       ++first_valid_jet;
       --num_valid_jets;
     }
     else if((unof_||qqxf_) && jets[jets.size()-1].delta_R(jets[jets.size()-2]) > R_eff){
       --num_valid_jets;
     }
     std::vector<int> np(jets.size(), 1);
     for(int i = 0; i < ng_jets; ++i){
       ++np[first_valid_jet + ran_.get().flat() * num_valid_jets];
     }
     weight_ *= std::pow(num_valid_jets, ng_jets);
     return np;
   }
 
 #ifndef NDEBUG
   namespace{
     bool tagged_FKL_backward(
         std::vector<fastjet::PseudoJet> const & jet_partons
     ){
       return std::find_if(
           begin(jet_partons), end(jet_partons),
           [](fastjet::PseudoJet const & p){
             return p.user_index() == backward_FKL_idx;
           }
       ) != end(jet_partons);
     }
 
     bool tagged_FKL_forward(
         std::vector<fastjet::PseudoJet> const & jet_partons
     ){
       // the most forward FKL parton is most likely near the end of jet_partons;
       // start search from there
       return std::find_if(
           jet_partons.rbegin(), jet_partons.rend(),
           [](fastjet::PseudoJet const & p){
             return p.user_index() == forward_FKL_idx;
           }
       ) != jet_partons.rend();
     }
 
     bool tagged_FKL_extremal(
         std::vector<fastjet::PseudoJet> const & jet_partons
     ){
       return tagged_FKL_backward(jet_partons) && tagged_FKL_forward(jet_partons);
     }
 
   } // namespace anonymous
 #endif
 
   std::vector<fastjet::PseudoJet> PhaseSpacePoint::split(
       std::vector<fastjet::PseudoJet> const & jets,
       int ng_jets
   ){
     return split(jets, distribute_jet_partons(ng_jets, jets));
   }
 
   bool PhaseSpacePoint::pass_extremal_cuts(
       fastjet::PseudoJet const & ext_parton,
       fastjet::PseudoJet const & jet
   ) const{
     if(ext_parton.pt() < param_.min_extparton_pt) return false;
     return (ext_parton - jet).pt()/jet.pt() < param_.max_ext_soft_pt_fraction;
   }
 
   std::vector<fastjet::PseudoJet> PhaseSpacePoint::split(
       std::vector<fastjet::PseudoJet> const & jets,
       std::vector<int> const & np
   ){
     assert(! jets.empty());
     assert(jets.size() == np.size());
     assert(pass_resummation_cuts(jets));
 
     const size_t most_backward_FKL_idx = 0 + unob_ + qqxb_;
     const size_t most_forward_FKL_idx = jets.size() - 1 - unof_ - qqxf_;
     const auto & jet = param_.jet_param;
     const JetSplitter jet_splitter{jet.def, jet.min_pt, ran_};
 
     std::vector<fastjet::PseudoJet> jet_partons;
     // randomly distribute jet gluons among jets
     for(size_t i = 0; i < jets.size(); ++i){
       auto split_res = jet_splitter.split(jets[i], np[i]);
       weight_ *= split_res.weight;
       if(weight_ == 0) return {};
       assert(
           std::all_of(
               begin(split_res.constituents), end(split_res.constituents),
               is_jet_parton
           )
       );
       const auto first_new_parton = jet_partons.insert(
           end(jet_partons),
           begin(split_res.constituents), end(split_res.constituents)
       );
       // mark uno and extremal FKL emissions here so we can check
       // their position once all emissions are generated
       auto extremal = end(jet_partons);
       if (i == most_backward_FKL_idx){ //FKL backward emission
         extremal = std::min_element(
             first_new_parton, end(jet_partons), rapidity_less{}
         );
         extremal->set_user_index(backward_FKL_idx);
       }
       else if(((unob_ || qqxb_) && i == 0)){
         // unordered/qqxb
         extremal = std::min_element(
             first_new_parton, end(jet_partons), rapidity_less{}
         );
         extremal->set_user_index((unob_)?unob_idx:qqxb_idx);
       }
 
       else if (i == most_forward_FKL_idx){
         extremal = std::max_element(
             first_new_parton, end(jet_partons), rapidity_less{}
         );
         extremal->set_user_index(forward_FKL_idx);
       }
       else if(((unof_ || qqxf_) && i == jets.size() - 1)){
         // unordered/qqxf
         extremal = std::max_element(
             first_new_parton, end(jet_partons), rapidity_less{}
         );
         extremal->set_user_index((unof_)?unof_idx:qqxf_idx);
       }
       if(
           extremal != end(jet_partons)
           && !pass_extremal_cuts(*extremal, jets[i])
       ){
         weight_ = 0;
         return {};
       }
     }
     assert(tagged_FKL_extremal(jet_partons));
     std::sort(begin(jet_partons), end(jet_partons), rapidity_less{});
     if(
         !extremal_ok(jet_partons)
         || !split_preserved_jets(jets, jet_partons)
     ){
       weight_ = 0.;
       return {};
     }
     return jet_partons;
   }
 
   bool PhaseSpacePoint::extremal_ok(
       std::vector<fastjet::PseudoJet> const & partons
   ) const{
     assert(std::is_sorted(begin(partons), end(partons), rapidity_less{}));
     if(unob_ && partons.front().user_index() !=  unob_idx) return false;
     if(unof_ && partons.back().user_index() !=  unof_idx) return false;
     if(qqxb_ && partons.front().user_index() !=  qqxb_idx) return false;
     if(qqxf_ && partons.back().user_index() !=  qqxf_idx) return false;
     return
       most_backward_FKL(partons).user_index() == backward_FKL_idx
       && most_forward_FKL(partons).user_index() == forward_FKL_idx;
   }
 
   bool PhaseSpacePoint::split_preserved_jets(
         std::vector<fastjet::PseudoJet> const & jets,
         std::vector<fastjet::PseudoJet> const & jet_partons
   ) const{
     assert(std::is_sorted(begin(jets), end(jets), rapidity_less{}));
 
     const auto split_jets = sorted_by_rapidity(cluster_jets(jet_partons));
     // this can happen if two overlapping jets
     // are both split into more than one parton
     if(split_jets.size() != jets.size()) return false;
     for(size_t i = 0; i < split_jets.size(); ++i){
       // this can happen if there are two overlapping jets
       // and a parton is assigned to the "wrong" jet
       if(!nearby_ep(jets[i].rapidity(), split_jets[i].rapidity(), 1e-2)){
         return false;
       }
     }
     return true;
   }
 
   template<class Particle>
   Particle const & PhaseSpacePoint::most_backward_FKL(
       std::vector<Particle> const & partons
   ) const{
     return partons[0 + unob_ + qqxb_];
   }
 
   template<class Particle>
   Particle const & PhaseSpacePoint::most_forward_FKL(
       std::vector<Particle> const & partons
   ) const{
     const size_t idx = partons.size() - 1 - unof_ - qqxf_;
     assert(idx < partons.size());
     return partons[idx];
   }
 
   template<class Particle>
   Particle & PhaseSpacePoint::most_backward_FKL(
       std::vector<Particle> & partons
   ) const{
     return partons[0 + unob_ + qqxb_];
   }
 
   template<class Particle>
   Particle & PhaseSpacePoint::most_forward_FKL(
       std::vector<Particle> & partons
   ) const{
     const size_t idx = partons.size() - 1 - unof_ - qqxf_;
     assert(idx < partons.size());
     return partons[idx];
   }
 
   namespace {
     bool contains_idx(
         fastjet::PseudoJet const & jet, fastjet::PseudoJet const & parton
     ){
       auto const & constituents = jet.constituents();
       const int idx = parton.user_index();
       return std::find_if(
           begin(constituents), end(constituents),
           [idx](fastjet::PseudoJet const & con){return con.user_index() == idx;}
       ) != end(constituents);
     }
   }
 
   /**
    * final jet test:
    *   - number of jets must match Born kinematics
    *   - no partons designated as nonjet may end up inside jets
    *   - all other outgoing partons *must* end up inside jets
    *   - the extremal (in rapidity) partons must be inside the extremal jets
    *   - rapidities must be the same (by construction)
    */
   bool PhaseSpacePoint::jets_ok(
       std::vector<fastjet::PseudoJet> const & Born_jets,
       std::vector<fastjet::PseudoJet> const & partons
   ) const{
     fastjet::ClusterSequence cs(partons, param_.jet_param.def);
     const auto jets = sorted_by_rapidity(cs.inclusive_jets(param_.jet_param.min_pt));
     if(jets.size() != Born_jets.size()) return false;
     int in_jet = 0;
     for(size_t i = 0; i < jets.size(); ++i){
       assert(jets[i].has_constituents());
       for(auto && parton: jets[i].constituents()){
         if(is_nonjet_parton(parton)) return false;
       }
       in_jet += jets[i].constituents().size();
     }
     const int expect_in_jet = std::count_if(
         partons.cbegin(), partons.cend(), is_jet_parton
     );
     if(in_jet != expect_in_jet) return false;
     // note that PseudoJet::contains does not work here
     if(! (
            contains_idx(most_backward_FKL(jets), most_backward_FKL(partons))
            &&  contains_idx(most_forward_FKL(jets), most_forward_FKL(partons))
        )) return false;
     if(unob_ && !contains_idx(jets.front(), partons.front())) return false;
     if(unof_ && !contains_idx(jets.back(), partons.back())) return false;
     for(size_t i = 0; i < jets.size(); ++i){
       assert(nearby_ep(jets[i].rapidity(), Born_jets[i].rapidity(), 1e-2));
     }
     return true;
   }
 
   void PhaseSpacePoint::reconstruct_incoming(
       std::array<Particle, 2> const & Born_incoming
   ){
     std::tie(incoming_[0].p, incoming_[1].p) = incoming_momenta(outgoing_);
     for(size_t i = 0; i < incoming_.size(); ++i){
       incoming_[i].type = Born_incoming[i].type;
     }
     assert(momentum_conserved());
   }
 
   double PhaseSpacePoint::phase_space_normalisation(
       int num_Born_jets, int num_out_partons
   ) const{
     return pow(16*pow(M_PI,3), num_Born_jets - num_out_partons);
   }
 
   bool PhaseSpacePoint::momentum_conserved() const{
     fastjet::PseudoJet diff;
     for(auto const & in: incoming()) diff += in.p;
     const double norm = diff.E();
     for(auto const & out: outgoing()) diff -= out.p;
     return nearby(diff, fastjet::PseudoJet{}, norm);
   }
 
 } //namespace HEJ