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diff --git a/include/HEJ/Event.hh b/include/HEJ/Event.hh
index a037a82..80a5694 100644
--- a/include/HEJ/Event.hh
+++ b/include/HEJ/Event.hh
@@ -1,210 +1,211 @@
/** \file
* \brief Declares the Event class and helpers
*
* \authors Jeppe Andersen, Tuomas Hapola, Marian Heil, Andreas Maier, Jennifer Smillie
* \date 2019
* \copyright GPLv2 or later
*/
#pragma once
#include <array>
#include <memory>
#include <string>
#include <unordered_map>
#include <vector>
#include "HEJ/event_types.hh"
#include "HEJ/Particle.hh"
#include "HEJ/RNG.hh"
#include "fastjet/ClusterSequence.hh"
namespace LHEF{
class HEPEUP;
class HEPRUP;
}
namespace fastjet{
class JetDefinition;
}
namespace HEJ{
struct ParameterDescription;
//! Event parameters
struct EventParameters{
double mur; /**< Value of the Renormalisation Scale */
double muf; /**< Value of the Factorisation Scale */
double weight; /**< Event Weight */
//! Optional description
std::shared_ptr<ParameterDescription> description = nullptr;
};
//! Description of event parameters
struct ParameterDescription {
//! Name of central scale choice (e.g. "H_T/2")
std::string scale_name;
//! Actual renormalisation scale divided by central scale
double mur_factor;
//! Actual factorisation scale divided by central scale
double muf_factor;
ParameterDescription() = default;
ParameterDescription(
std::string scale_name, double mur_factor, double muf_factor
):
scale_name{scale_name}, mur_factor{mur_factor}, muf_factor{muf_factor}
{};
};
//! An event before jet clustering & classification
struct UnclusteredEvent{
//! Default Constructor
UnclusteredEvent() = default;
//! Constructor from LesHouches event information
UnclusteredEvent(LHEF::HEPEUP const & hepeup);
std::array<Particle, 2> incoming; /**< Incoming Particles */
std::vector<Particle> outgoing; /**< Outgoing Particles */
//! Particle decays in the format {outgoing index, decay products}
std::unordered_map<size_t, std::vector<Particle>> decays;
//! Central parameter (e.g. scale) choice
EventParameters central;
std::vector<EventParameters> variations; /**< For parameter variation */
};
/** An event with clustered jets
*
* This is the main HEJ 2 event class.
* It contains kinematic information including jet clustering,
* parameter (e.g. scale) settings and the event weight.
*/
class Event{
public:
//! Default Event Constructor
Event() = default;
//! Event Constructor adding jet clustering to an unclustered event
Event(
UnclusteredEvent ev,
fastjet::JetDefinition const & jet_def, double min_jet_pt
);
//! The jets formed by the outgoing partons
std::vector<fastjet::PseudoJet> jets() const;
//! The corresponding event before jet clustering
UnclusteredEvent const & unclustered() const {
return ev_;
}
//! Central parameter choice
EventParameters const & central() const{
return ev_.central;
}
//! Central parameter choice
EventParameters & central(){
return ev_.central;
}
//! Incoming particles
std::array<Particle, 2> const & incoming() const{
return ev_.incoming;
}
//! Outgoing particles
std::vector<Particle> const & outgoing() const{
return ev_.outgoing;
}
//! Particle decays
/**
* The key in the returned map corresponds to the index in the
* vector returned by outgoing()
*/
std::unordered_map<size_t, std::vector<Particle>> const & decays() const{
return ev_.decays;
}
//! Parameter (scale) variations
std::vector<EventParameters> const & variations() const{
return ev_.variations;
}
//! Parameter (scale) variations
std::vector<EventParameters> & variations(){
return ev_.variations;
}
//! Parameter (scale) variation
/**
* @param i Index of the requested variation
*/
EventParameters const & variations(size_t i) const{
return ev_.variations[i];
}
//! Parameter (scale) variation
/**
* @param i Index of the requested variation
*/
EventParameters & variations(size_t i){
return ev_.variations[i];
}
//! Indices of the jets the outgoing partons belong to
/**
* @param jets Jets to be tested
* @returns A vector containing, for each outgoing parton,
* the index in the vector of jets the considered parton
* belongs to. If the parton is not inside any of the
* passed jets, the corresponding index is set to -1.
*/
std::vector<int> particle_jet_indices(
std::vector<fastjet::PseudoJet> const & jets
) const{
return cs_.particle_jet_indices(jets);
}
//! Jet definition used for clustering
fastjet::JetDefinition const & jet_def() const{
return cs_.jet_def();
}
//! Minimum jet transverse momentum
double min_jet_pt() const{
return min_jet_pt_;
}
//! Event type
event_type::EventType type() const{
return type_;
}
//! Assign colours to each particle
/**
+ * @returns true if new colour generated, i.e. same as is_HEJ()
* @details Colour ordering is done according to leading colour in the MRK
* limit, see \cite Andersen:2011zd. This only affects \ref
* is_HEJ() "HEJ" configurations, all other \ref event_type
* "EventTypes" will be ignored.
* @note This overwrites all previous set colours.
*/
- void generate_colour_flow(HEJ::RNG &);
+ bool generate_colour_flow(HEJ::RNG &);
private:
void sort(); /**< Sort Particles in rapidity **/
UnclusteredEvent ev_;
fastjet::ClusterSequence cs_;
double min_jet_pt_;
event_type::EventType type_;
};
//! Square of the partonic centre-of-mass energy \f$\hat{s}\f$
double shat(Event const & ev);
//! Convert an event to a LHEF::HEPEUP
LHEF::HEPEUP to_HEPEUP(Event const & event, LHEF::HEPRUP *);
}
diff --git a/src/Event.cc b/src/Event.cc
index 5df9421..1f233c9 100644
--- a/src/Event.cc
+++ b/src/Event.cc
@@ -1,477 +1,474 @@
/**
* \authors Jeppe Andersen, Tuomas Hapola, Marian Heil, Andreas Maier, Jennifer Smillie
* \date 2019
* \copyright GPLv2 or later
*/
#include "HEJ/Event.hh"
#include <algorithm>
#include <assert.h>
#include <numeric>
#include <utility>
#include "LHEF/LHEF.h"
#include "fastjet/JetDefinition.hh"
#include "HEJ/Constants.hh"
#include "HEJ/exceptions.hh"
#include "HEJ/PDG_codes.hh"
namespace HEJ{
namespace{
constexpr int status_in = -1;
constexpr int status_decayed = 2;
constexpr int status_out = 1;
/// @name helper functions to determine event type
//@{
/**
* \brief check if final state valid for HEJ
*
* check if there is at most one photon, W, H, Z in the final state
* and all the rest are quarks or gluons
*/
bool final_state_ok(std::vector<Particle> const & outgoing){
bool has_AWZH_boson = false;
for(auto const & out: outgoing){
if(is_AWZH_boson(out.type)){
if(has_AWZH_boson) return false;
has_AWZH_boson = true;
}
else if(! is_parton(out.type)) return false;
}
return true;
}
template<class Iterator>
Iterator remove_AWZH(Iterator begin, Iterator end){
return std::remove_if(
begin, end, [](Particle const & p){return is_AWZH_boson(p);}
);
}
template<class Iterator>
bool valid_outgoing(Iterator begin, Iterator end){
return std::distance(begin, end) >= 2
&& std::is_sorted(begin, end, rapidity_less{})
&& std::count_if(
begin, end, [](Particle const & s){return is_AWZH_boson(s);}
) < 2;
}
/// @note that this changes the outgoing range!
template<class ConstIterator, class Iterator>
bool is_FKL(
ConstIterator begin_incoming, ConstIterator end_incoming,
Iterator begin_outgoing, Iterator end_outgoing
){
assert(std::distance(begin_incoming, end_incoming) == 2);
assert(std::distance(begin_outgoing, end_outgoing) >= 2);
// One photon, W, H, Z in the final state is allowed.
// Remove it for remaining tests,
end_outgoing = remove_AWZH(begin_outgoing, end_outgoing);
// Test if this is a standard FKL configuration.
return
(begin_incoming->type == begin_outgoing->type)
&& ((end_incoming-1)->type == (end_outgoing-1)->type)
&& std::all_of(
begin_outgoing + 1, end_outgoing - 1,
[](Particle const & p){ return p.type == pid::gluon; }
);
}
bool is_FKL(
std::array<Particle, 2> const & incoming,
std::vector<Particle> outgoing
){
assert(std::is_sorted(begin(incoming), end(incoming), pz_less{}));
assert(valid_outgoing(begin(outgoing), end(outgoing)));
return is_FKL(
begin(incoming), end(incoming),
begin(outgoing), end(outgoing)
);
}
bool has_2_jets(Event const & event){
return event.jets().size() >= 2;
}
/**
* \brief Checks whether event is unordered backwards
* @param ev Event
* @returns Is Event Unordered Backwards
*
* - Checks there is more than 3 constuents in the final state
* - Checks there is more than 3 jets
* - Checks the most backwards parton is a gluon
* - Checks the most forwards jet is not a gluon
* - Checks the rest of the event is FKL
* - Checks the second most backwards is not a different boson
* - Checks the unordered gluon actually forms a jet
*/
bool is_unordered_backward(Event const & ev){
auto const & in = ev.incoming();
auto const & out = ev.outgoing();
assert(std::is_sorted(begin(in), end(in), pz_less{}));
assert(valid_outgoing(begin(out), end(out)));
if(out.size() < 3) return false;
if(ev.jets().size() < 3) return false;
if(in.front().type == pid::gluon) return false;
if(out.front().type != pid::gluon) return false;
// When skipping the unordered emission
// the remainder should be a regular FKL event,
// except that the (new) first outgoing particle must not be a A,W,Z,H.
const auto FKL_begin = next(begin(out));
if(is_AWZH_boson(*FKL_begin)) return false;
if(!is_FKL(in, {FKL_begin, end(out)})) return false;
// check that the unordered gluon forms an extra jet
const auto jets = sorted_by_rapidity(ev.jets());
const auto indices = ev.particle_jet_indices({jets.front()});
return indices[0] >= 0 && indices[1] == -1;
}
/**
* \brief Checks for a forward unordered gluon emission
* @param ev Event
* @returns Is the event a forward unordered emission
*
* \see is_unordered_backward
*/
bool is_unordered_forward(Event const & ev){
auto const & in = ev.incoming();
auto const & out = ev.outgoing();
assert(std::is_sorted(begin(in), end(in), pz_less{}));
assert(valid_outgoing(begin(out), end(out)));
if(out.size() < 3) return false;
if(ev.jets().size() < 3) return false;
if(in.back().type == pid::gluon) return false;
if(out.back().type != pid::gluon) return false;
// When skipping the unordered emission
// the remainder should be a regular FKL event,
// except that the (new) last outgoing particle must not be a A,W,Z,H.
const auto FKL_end = prev(end(out));
if(is_AWZH_boson(*prev(FKL_end))) return false;
if(!is_FKL(in, {begin(out), FKL_end})) return false;
// check that the unordered gluon forms an extra jet
const auto jets = sorted_by_rapidity(ev.jets());
const auto indices = ev.particle_jet_indices({jets.back()});
return indices.back() >= 0 && indices[indices.size()-2] == -1;
}
using event_type::EventType;
EventType classify(Event const & ev){
if(! final_state_ok(ev.outgoing())) return EventType::bad_final_state;
if(! has_2_jets(ev)) return EventType::no_2_jets;
if(is_FKL(ev.incoming(), ev.outgoing())) return EventType::FKL;
if(is_unordered_backward(ev)){
return EventType::unordered_backward;
}
if(is_unordered_forward(ev)){
return EventType::unordered_forward;
}
return EventType::nonHEJ;
}
//@}
Particle extract_particle(LHEF::HEPEUP const & hepeup, int i){
const ParticleID id = static_cast<ParticleID>(hepeup.IDUP[i]);
const fastjet::PseudoJet momentum{
hepeup.PUP[i][0], hepeup.PUP[i][1],
hepeup.PUP[i][2], hepeup.PUP[i][3]
};
if(is_parton(id))
return Particle{ id, std::move(momentum), hepeup.ICOLUP[i] };
return Particle{ id, std::move(momentum), {} };
}
bool is_decay_product(std::pair<int, int> const & mothers){
if(mothers.first == 0) return false;
return mothers.second == 0 || mothers.first == mothers.second;
}
} // namespace anonymous
UnclusteredEvent::UnclusteredEvent(LHEF::HEPEUP const & hepeup):
central(EventParameters{
hepeup.scales.mur, hepeup.scales.muf, hepeup.weight()
})
{
size_t in_idx = 0;
for (int i = 0; i < hepeup.NUP; ++i) {
// skip decay products
// we will add them later on, but we have to ensure that
// the decayed particle is added before
if(is_decay_product(hepeup.MOTHUP[i])) continue;
auto particle = extract_particle(hepeup, i);
// needed to identify mother particles for decay products
particle.p.set_user_index(i+1);
if(hepeup.ISTUP[i] == status_in){
if(in_idx > incoming.size()) {
throw std::invalid_argument{
"Event has too many incoming particles"
};
}
incoming[in_idx++] = std::move(particle);
}
else outgoing.emplace_back(std::move(particle));
}
// add decay products
for (int i = 0; i < hepeup.NUP; ++i) {
if(!is_decay_product(hepeup.MOTHUP[i])) continue;
const int mother_id = hepeup.MOTHUP[i].first;
const auto mother = std::find_if(
begin(outgoing), end(outgoing),
[mother_id](Particle const & particle){
return particle.p.user_index() == mother_id;
}
);
if(mother == end(outgoing)){
throw std::invalid_argument{"invalid decay product parent"};
}
const int mother_idx = std::distance(begin(outgoing), mother);
assert(mother_idx >= 0);
decays[mother_idx].emplace_back(extract_particle(hepeup, i));
}
}
namespace {
- int connect_incoming(Particle & part, int & colour, int & anti_colour){
- part.colour = std::make_pair(anti_colour, colour);
+ void connect_incoming(Particle & in, int & colour, int & anti_colour){
+ in.colour = std::make_pair(anti_colour, colour);
// gluon
- if(part.type == pid::gluon) {
- return 0;
- }
- // q
- if(part.type > 0){
- part.colour->second = 0;
+ if(in.type == pid::gluon)
+ return;
+ if(in.type > 0){
+ // quark
+ assert(is_quark(in));
+ in.colour->second = 0;
colour*=-1;
- return -1;
+ return;
}
- // qx
- part.colour->first = 0;
+ // anti-quark
+ assert(is_antiquark(in));
+ in.colour->first = 0;
anti_colour*=-1;
- return +1;
+ return;
}
}
- void Event::generate_colour_flow(RNG & ran){
- // only sort HEJ events
+ bool Event::generate_colour_flow(RNG & ran){
+ // generate only for HEJ events
if(!event_type::is_HEJ(type()))
- return;
-
+ return false;
assert(std::is_sorted(
begin(outgoing()), end(outgoing()), rapidity_less{}));
assert(incoming()[0].pz() < incoming()[1].pz());
- // initialise first
+ // positive (anti-)colour -> can connect
+ // negative (anti-)colour -> not available/used up by (anti-)quark
int colour = COLOUR_OFFSET;
int anti_colour = colour+1;
- // -1 anti, 0 no, +1 colour
- int is_quark_line = connect_incoming(ev_.incoming[0], colour, anti_colour);
+ // initialise first
+ connect_incoming(ev_.incoming[0], colour, anti_colour);
for(auto & part: ev_.outgoing){
+ assert(colour>0 || anti_colour>0);
if(part.type == ParticleID::gluon){
// gluon
- if(is_quark_line == 0){
+ if(colour>0 && anti_colour>0){
// on g line => connect to colour OR anti-colour (random)
if(ran.flat() < 0.5){
part.colour = std::make_pair(colour+2,colour);
colour+=2;
} else {
part.colour = std::make_pair(anti_colour, anti_colour+2);
anti_colour+=2;
}
- } else if(is_quark_line > 0){
+ } else if(colour > 0){
// on q line => connect to available colour
part.colour = std::make_pair(colour+2, colour);
colour+=2;
} else {
+ assert(colour<0 && anti_colour>0);
// on qx line => connect to available anti-colour
part.colour = std::make_pair(anti_colour, anti_colour+2);
anti_colour+=2;
}
} else if(is_quark(part)) {
// quark
- if(is_quark_line == 0){
- // on g line => connect and remove colour
- is_quark_line = 1;
+ assert(anti_colour>0);
+ if(colour>0){
+ // on g line => connect and remove anti-colour
part.colour = std::make_pair(anti_colour, 0);
anti_colour+=2;
anti_colour*=-1;
- } else if(is_quark_line < 0){
+ } else {
// on qx line => new colour
- is_quark_line = 0;
colour*=-1;
- part.colour = std::make_pair(colour,0);
-
- } else {
- throw std::logic_error("Colour connection impossible: Expected anti-quark but found quark.");
+ part.colour = std::make_pair(colour, 0);
}
} else if(is_antiquark(part)) {
// anti-quark
- if(is_quark_line == 0){
- // on g line => connect and remove anti-colour
- is_quark_line = -1;
+ assert(colour>0);
+ if(anti_colour>0){
+ // on g line => connect and remove colour
part.colour = std::make_pair(0, colour);
colour+=2;
colour*=-1;
- } else if(is_quark_line > 0){
+ } else {
// on q line => new anti-colour
- is_quark_line = 0;
anti_colour*=-1;
- part.colour = std::make_pair(0,anti_colour);
- } else {
- throw std::logic_error("Colour connection impossible: Expected quark but found anti-quark.");
+ part.colour = std::make_pair(0, anti_colour);
}
}
+ // else not a parton
}
// Connect last
connect_incoming(ev_.incoming[1], anti_colour, colour);
-
+ return true;
}
void Event::sort(){
// sort incoming
std::sort(
begin(ev_.incoming), end(ev_.incoming),
[](Particle o1, Particle o2){return o1.p.pz()<o2.p.pz();}
);
//sort outgoing
if(std::is_sorted(begin(ev_.outgoing), end(ev_.outgoing), rapidity_less{}))
return;
auto old_outgoing = std::move(ev_.outgoing);
std::vector<size_t> idx(old_outgoing.size());
std::iota(idx.begin(), idx.end(), 0);
std::sort(idx.begin(), idx.end(), [&old_outgoing](size_t i, size_t j){
return old_outgoing[i].rapidity() < old_outgoing[j].rapidity();
});
ev_.outgoing.clear();
for(size_t i: idx) {
ev_.outgoing.emplace_back(std::move(old_outgoing[i]));
}
// find decays again
if(!ev_.decays.empty()){
auto old_decays = std::move(ev_.decays);
ev_.decays.clear();
for(size_t i=0; i<idx.size(); ++i) {
auto decay = old_decays.find(idx[i]);
if(decay != old_decays.end())
ev_.decays.emplace(i, std::move(decay->second));
}
assert(old_decays.size() == ev_.decays.size());
}
}
Event::Event(
UnclusteredEvent ev,
fastjet::JetDefinition const & jet_def, double min_jet_pt
):
ev_{std::move(ev)},
cs_{to_PseudoJet(filter_partons(ev_.outgoing)), jet_def},
min_jet_pt_{min_jet_pt}
{
// sort particles
sort();
// classify event
type_ = classify(*this);
assert(std::is_sorted(begin(outgoing()), end(outgoing()), rapidity_less{}));
}
std::vector<fastjet::PseudoJet> Event::jets() const{
return cs_.inclusive_jets(min_jet_pt_);
}
double shat(Event const & ev){
return (ev.incoming()[0].p + ev.incoming()[1].p).m2();
}
LHEF::HEPEUP to_HEPEUP(Event const & event, LHEF::HEPRUP * heprup){
LHEF::HEPEUP result;
result.heprup = heprup;
result.weights = {{event.central().weight, nullptr}};
for(auto const & var: event.variations()){
result.weights.emplace_back(var.weight, nullptr);
}
size_t num_particles = event.incoming().size() + event.outgoing().size();
for(auto const & decay: event.decays()) num_particles += decay.second.size();
result.NUP = num_particles;
// the following entries are pretty much meaningless
result.IDPRUP = event.type()+1; // event ID
result.AQEDUP = 1./128.; // alpha_EW
//result.AQCDUP = 0.118 // alpha_QCD
// end meaningless part
result.XWGTUP = event.central().weight;
result.SCALUP = event.central().muf;
result.scales.muf = event.central().muf;
result.scales.mur = event.central().mur;
result.scales.SCALUP = event.central().muf;
result.pdfinfo.p1 = event.incoming().front().type;
result.pdfinfo.p2 = event.incoming().back().type;
result.pdfinfo.scale = event.central().muf;
result.IDUP.reserve(num_particles); // PID
result.ISTUP.reserve(num_particles); // status (in, out, decay)
result.PUP.reserve(num_particles); // momentum
result.MOTHUP.reserve(num_particles); // index mother particle
result.ICOLUP.reserve(num_particles); // colour
// incoming
for(Particle const & in: event.incoming()){
result.IDUP.emplace_back(in.type);
result.ISTUP.emplace_back(status_in);
result.PUP.push_back({in.p[0], in.p[1], in.p[2], in.p[3], in.p.m()});
result.MOTHUP.emplace_back(0, 0);
assert(in.colour);
result.ICOLUP.emplace_back(*in.colour);
}
// outgoing
for(size_t i = 0; i < event.outgoing().size(); ++i){
Particle const & out = event.outgoing()[i];
result.IDUP.emplace_back(out.type);
const int status = event.decays().count(i)?status_decayed:status_out;
result.ISTUP.emplace_back(status);
result.PUP.push_back({out.p[0], out.p[1], out.p[2], out.p[3], out.p.m()});
result.MOTHUP.emplace_back(1, 2);
if(out.colour)
result.ICOLUP.emplace_back(*out.colour);
else{
assert(is_AWZH_boson(out));
result.ICOLUP.emplace_back(std::make_pair(0,0));
}
}
// decays
for(auto const & decay: event.decays()){
for(auto const out: decay.second){
result.IDUP.emplace_back(out.type);
result.ISTUP.emplace_back(status_out);
result.PUP.push_back({out.p[0], out.p[1], out.p[2], out.p[3], out.p.m()});
const size_t mother_idx = 1 + event.incoming().size() + decay.first;
result.MOTHUP.emplace_back(mother_idx, mother_idx);
result.ICOLUP.emplace_back(0,0);
}
}
assert(result.ICOLUP.size() == num_particles);
static constexpr double unknown_spin = 9.; //per Les Houches accord
result.VTIMUP = std::vector<double>(num_particles, unknown_spin);
result.SPINUP = result.VTIMUP;
return result;
}
}

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