diff --git a/FixedOrderGen/src/EventGenerator.cc b/FixedOrderGen/src/EventGenerator.cc
index 4380eac..2fe6def 100644
--- a/FixedOrderGen/src/EventGenerator.cc
+++ b/FixedOrderGen/src/EventGenerator.cc
@@ -1,81 +1,78 @@
#include "EventGenerator.hh"
#include "Process.hh"
#include "Beam.hh"
#include "JetParameters.hh"
#include "PhaseSpacePoint.hh"
#include "HEJ/Event.hh"
#include "HEJ/config.hh"
namespace HEJFOG{
EventGenerator::EventGenerator(
Process process,
Beam beam,
HEJ::ScaleGenerator scale_gen,
JetParameters jets,
int pdf_id,
double uno_chance,
ParticlesPropMap particles_properties,
HEJ::HiggsCouplingSettings Higgs_coupling,
HEJ::RNG & ran
):
pdf_{pdf_id, beam.particles[0], beam.particles[1]},
ME_{
[this](double mu){ return pdf_.Halphas(mu); },
HEJ::MatrixElementConfig{
- HEJ::JetParameters{jets.def, jets.min_pt},
false,
std::move(Higgs_coupling)
}
},
scale_gen_{std::move(scale_gen)},
process_{std::move(process)},
jets_{std::move(jets)},
beam_{std::move(beam)},
uno_chance_{uno_chance},
particles_properties_{std::move(particles_properties)},
ran_{ran}
{
}
HEJ::Event EventGenerator::gen_event(){
HEJFOG::PhaseSpacePoint psp{
process_,
jets_,
pdf_, beam_.energy,
uno_chance_,
particles_properties_,
ran_
};
status_ = psp.status();
if(status_ != good) return {};
HEJ::Event ev = scale_gen_(
HEJ::Event{
to_UnclusteredEvent(std::move(psp)),
jets_.def, jets_.min_pt
}
);
const double shat = HEJ::shat(ev);
const double xa = (ev.incoming()[0].E()-ev.incoming()[0].pz())/(2.*beam_.energy);
const double xb = (ev.incoming()[1].E()+ev.incoming()[1].pz())/(2.*beam_.energy);
// evaluate matrix element on this point
- ev.central().weight *= ME_.tree(
- ev.central().mur, ev.incoming(), ev.outgoing(), false
- )/(shat*shat);
+ const auto ME_weights = ME_.tree(ev, false);
+ ev.central().weight *= ME_weights.central/(shat*shat);
ev.central().weight *= pdf_.pdfpt(0,xa,ev.central().muf, ev.incoming()[0].type);
ev.central().weight *= pdf_.pdfpt(0,xb,ev.central().muf, ev.incoming()[1].type);
- for(auto & var: ev.variations()){
- var.weight *= ME_.tree(
- var.mur, ev.incoming(), ev.outgoing(), false
- )/(shat*shat);
+ for(size_t i = 0; i < ev.variations().size(); ++i){
+ auto & var = ev.variations(i);
+ var.weight *= ME_weights.variations[i]/(shat*shat);
var.weight *= pdf_.pdfpt(0,xa,var.muf, ev.incoming()[0].type);
var.weight *= pdf_.pdfpt(0,xb,var.muf, ev.incoming()[1].type);
}
return ev;
}
}
diff --git a/include/HEJ/Event.hh b/include/HEJ/Event.hh
index 6ad19e5..51f9f50 100644
--- a/include/HEJ/Event.hh
+++ b/include/HEJ/Event.hh
@@ -1,186 +1,186 @@
/** \file
* \brief Declares the Event class and helpers
*
*/
#pragma once
#include <string>
#include <memory>
#include <unordered_map>
#include "HEJ/utility.hh"
#include "HEJ/event_types.hh"
#include "LHEF/LHEF.h"
#include "fastjet/JetDefinition.hh"
#include "fastjet/ClusterSequence.hh"
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
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_;
}
private:
UnclusteredEvent ev_;
fastjet::ClusterSequence cs_;
double min_jet_pt_;
event_type::EventType type_;
};
- //! Square of the partonic centre-of-mass energy
+ //! 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/include/HEJ/EventReweighter.hh b/include/HEJ/EventReweighter.hh
index a3f3279..8e33d2d 100644
--- a/include/HEJ/EventReweighter.hh
+++ b/include/HEJ/EventReweighter.hh
@@ -1,136 +1,181 @@
/** \file
* \brief Declares the EventReweighter class
*
* EventReweighter is the main class used within HEJ 2. It reweights the
* resummation events.
*/
#pragma once
#include "fastjet/PseudoJet.hh"
#include "fastjet/ClusterSequence.hh"
#include "LHEF/LHEF.h"
#include "HEJ/config.hh"
#include "HEJ/PDF.hh"
#include "HEJ/utility.hh"
#include "HEJ/Event.hh"
#include "HEJ/event_types.hh"
#include "HEJ/PhaseSpacePoint.hh"
#include "HEJ/MatrixElement.hh"
#include "HEJ/RNG.hh"
namespace HEJ{
//! Beam parameters
/**
* Currently, only symmetric beams are supported,
* so there is a single beam energy.
*/
struct Beam{
double E; /**< Beam energy */
std::array<ParticleID, 2> type; /**< Beam particles */
};
//! Main class for reweighting events in HEJ.
class EventReweighter{
using EventType = event_type::EventType;
public:
EventReweighter(
Beam beam, /**< Beam Energy */
int pdf_id, /**< PDF ID */
ScaleGenerator scale_gen, /**< Scale settings */
EventReweighterConfig conf, /**< Configuration parameters */
HEJ::RNG & ran /**< Random number generator */
);
EventReweighter(
LHEF::HEPRUP const & heprup, /**< LHEF event header */
ScaleGenerator scale_gen, /**< Scale settings */
EventReweighterConfig conf, /**< Configuration parameters */
HEJ::RNG & ran /**< Random number generator */
);
//! Get the used pdf
PDF const & pdf() const;
//! Generate resummation events for a given fixed-order event
/**
* @param ev Fixed-order event corresponding
* to the resummation events
* @param num_events Number of trial resummation configurations.
* @returns A vector of resummation events.
*
* The result vector depends on the type of the input event and the
* treatment of different types as specified in the constructor:
*
* \ref reweight The result vector contains between
* 0 and num_events resummation events.
*
* \ref keep If the input event passes the resummation jet cuts
* the result vector contains one event. Otherwise it is empty.
*
* \ref discard The result vector is empty
*/
std::vector<Event> reweight(
Event const & ev,
int num_events
);
private:
- struct EventFactors{
- double central;
- std::vector<double> variations;
- };
-
template<typename... T>
PDF const & pdf(T&& ...);
+ /** \internal
+ * \brief main generation/reweighting function:
+ * generate phase space points and divide out Born factors
+ */
std::vector<Event> gen_res_events(
Event const & ev, int num_events
);
std::vector<Event> rescale(
Event const & Born_ev, std::vector<Event> events
) const;
+ /** \internal
+ * \brief Do the Jets pass the resummation Cuts?
+ *
+ * @param ev Event in Question
+ * @returns 0 or 1 depending on if ev passes Jet Cuts
+ */
bool jets_pass_resummation_cuts(Event const & ev) const;
- EventFactors pdf_factors(Event const & ev) const;
-
- EventFactors matrix_elements(Event const & ev) const;
+ /** \internal
+ * \brief pdf_factors Function
+ *
+ * @param ev Event in Question
+ * @returns EventFactor due to PDFs
+ *
+ * Calculates the Central value and the variation due
+ * to the PDF choice made.
+ */
+ Weights pdf_factors(Event const & ev) const;
+
+ /** \internal
+ * \brief matrix_elements Function
+ *
+ * @param ev Event in question
+ * @returns EventFactor due to MatrixElements
+ *
+ * Calculates the Central value and the variation due
+ * to the Matrix Element.
+ */
+ Weights matrix_elements(Event const & ev) const;
- EventFactors fixed_order_scale_ME(Event const & ev) const;
+ /** \internal
+ * \brief Scale-dependent part of fixed-order matrix element
+ *
+ * @param ev Event in question
+ * @returns EventFactor scale variation due to FO-ME.
+ *
+ * This is only called to compute the scale variation for events where
+ * we don't do resummation (e.g. non-FKL).
+ * Since at tree level the scale dependence is just due to alpha_s,
+ * it is enough to return the alpha_s(mur) factors in the matrix element.
+ * The rest drops out in the ratio of (output event ME)/(input event ME),
+ * so we never have to compute it.
+ */
+ Weights fixed_order_scale_ME(Event const & ev) const;
+ /** \internal
+ * \brief Computes the tree level matrix element
+ *
+ * @param ev Event in Question
+ * @returns HEJ approximation to Tree level Matrix Element
+ *
+ * This computes the HEJ approximation to the tree level FO
+ * Matrix element which is used within the LO weighting process.
+ */
double tree_matrix_element(Event const & ev) const;
//! \internal General parameters
EventReweighterConfig param_;
//! \internal Beam energy
double E_beam_;
//! \internal PDF
PDF pdf_;
//! \internal Object to calculate the square of the matrix element
MatrixElement MEt2_;
//! \internal Object to calculate event renormalisation and factorisation scales
ScaleGenerator scale_gen_;
- //! \internal random number generator
- /**
- * \internal We use a reference_wrapper so that EventReweighter objects can
- * still be copied (which would be impossible with a reference).
+ /** \internal random number generator
+ *
+ * \note We use a reference_wrapper so that EventReweighter objects can
+ * still be copied (which would be impossible with a reference).
*/
std::reference_wrapper<HEJ::RNG> ran_;
};
template<typename... T>
PDF const & EventReweighter::pdf(T&&... t){
return pdf_ = PDF{std::forward<T>(t)...};
}
}
diff --git a/include/HEJ/MatrixElement.hh b/include/HEJ/MatrixElement.hh
index 429b648..ebbc7f4 100644
--- a/include/HEJ/MatrixElement.hh
+++ b/include/HEJ/MatrixElement.hh
@@ -1,208 +1,163 @@
/** \file
* \brief Contains the MatrixElement Class
*/
#pragma once
#include <functional>
#include "HEJ/config.hh"
#include "HEJ/utility.hh"
#include "HEJ/HiggsCouplingSettings.hh"
+#include "HEJ/Weights.hh"
#include "CLHEP/Vector/LorentzVector.h"
namespace HEJ{
+ class Event;
//! Class to calculate the squares of matrix elements
class MatrixElement{
public:
/** \brief MatrixElement Constructor
* @param alpha_s Function taking the renormalisation scale
* and returning the strong coupling constant
* @param conf General matrix element settings
*/
MatrixElement(
std::function<double (double)> alpha_s,
MatrixElementConfig conf
);
/**
- * \brief regulated HEJ matrix element
- * @param mur Value of the renormalisation scale
- * @param incoming Incoming particles
- * @param outgoing Outgoing particles
+ * \brief squares of regulated HEJ matrix elements
+ * @param event The event for which to calculate matrix elements
* @param check_momenta Special treatment for partons inside extremal jets
- * @returns The HEJ matrix element including virtual corrections
+ * @returns The squares of HEJ matrix elements including virtual corrections
*
* cf. eq. (22) in \cite Andersen:2011hs
- * Incoming particles should be ordered by ascending z momentum.
- * Outgoing particles should be ordered by ascending rapidity.
*
* \internal Relation to standard HEJ Met2: MatrixElement = Met2*shat^2/(pdfta*pdftb)
*/
- double operator()(
- double mur,
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing,
+ Weights operator()(
+ Event const & event,
bool check_momenta
) const;
- //! HEJ tree-level matrix element
+ //! Squares of HEJ tree-level matrix elements
/**
- * @param mur Value of the renormalisation scale
- * @param incoming Incoming particles
- * @param outgoing Outgoing particles
+ * @param event The event for which to calculate matrix elements
* @param check_momenta Special treatment for partons inside extremal jets
- * @returns The HEJ matrix element without virtual corrections
+ * @returns The squares of HEJ matrix elements without virtual corrections
*
* cf. eq. (22) in \cite Andersen:2011hs
- * Incoming particles should be ordered by ascending z momentum.
- * Outgoing particles should be ordered by ascending rapidity.
*/
- double tree(
- double mur,
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing,
- bool check_momenta
- ) const;
-
- //! HEJ tree-level matrix element - parametric part
- /**
- * @param mur Value of the renormalisation scale
- * @param incoming Incoming particles
- * @param outgoing Outgoing particles
- * @returns The parametric part of the tree matrix element
- *
- * cf. eq. (22) in \cite Andersen:2011hs
- *
- * The tree level matrix element factorises into a parametric part
- * which depends on the theory parameters (alpha_s and scale)
- * and a kinematic part comprising the dependence on the particle momenta
- * and colour factors. This function returns the former.
- */
- double tree_param(
- double mur,
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing
- ) const;
-
- //! HEJ tree-level matrix element - kinematic part
- /**
- * @param incoming Incoming particles
- * @param outgoing Outgoing particles
- * @param check_momenta Special treatment for partons inside extremal jets
- * @returns The kinematic part of the tree matrix element
- *
- * cf. eq. (22) in \cite Andersen:2011hs
- * Incoming particles should be ordered by ascending z momentum.
- * Outgoing particles should be ordered by ascending rapidity.
- *
- * The tree level matrix element factorises into a parametric part
- * which depends on the theory parameters (alpha_s and scale)
- * and a kinematic part comprising the dependence on the particle momenta
- * and colour factors. This function returns the latter.
- */
- double tree_kin(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing,
+ Weights tree(
+ Event const & event,
bool check_momenta
) const;
/**
- * \brief Calculates the Virtual Corrections
- * @param mur Value of the renormalisation scale
- * @param in Incoming particles
- * @param out Outgoing particles
- * @returns The Virtual Corrections of the Matrix Element
- *
- * Incoming particles should be ordered by ascending z momentum.
- * Outgoing particles should be ordered by ascending rapidity.
+ * \brief Virtual corrections to matrix element squares
+ * @param event The event for which to calculate matrix elements
+ * @returns The virtual corrections to the squares of the matrix elements
*
* The all order virtual corrections to LL in the MRK limit is
* given by replacing 1/t in the scattering amplitude according to the
* lipatov ansatz.
*
* cf. second-to-last line of eq. (22) in \cite Andersen:2011hs
* note that indices are off by one, i.e. out[0].p corresponds to p_1
*/
- double virtual_corrections(
- double mur,
- std::array<Particle, 2> const & in,
- std::vector<Particle> const & out
+ Weights virtual_corrections(
+ Event const & event
) const;
private:
+
+ Weights tree_param(
+ Event const & event
+ ) const;
+
+ double tree_kin(
+ Event const & event,
+ bool check_momenta
+ ) const;
+
+ double tree_param(
+ Event const & event,
+ double mur
+ ) const;
+
+ double virtual_corrections(
+ Event const & event,
+ double mur
+ ) const;
+
//! \internal cf. last line of eq. (22) in \cite Andersen:2011hs
double omega0(
double alpha_s, double mur,
fastjet::PseudoJet const & q_j, double lambda
) const;
double tree_kin_jets(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> partons,
+ Event const & ev,
bool check_momenta
) const;
double tree_kin_Higgs(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing,
+ Event const & ev,
bool check_momenta
) const;
double tree_kin_Higgs_first(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing,
+ Event const & ev,
bool check_momenta
) const;
double tree_kin_Higgs_last(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing,
+ Event const & ev,
bool check_momenta
) const;
/**
* \internal
* \brief Higgs inbetween extremal partons.
*
* Note that in the case of unordered emission, the Higgs is *always*
* treated as if in between the extremal (FKL) partons, even if its
* rapidity is outside the extremal parton rapidities
*/
double tree_kin_Higgs_between(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing,
+ Event const & ev,
bool check_momenta
) const;
double tree_param_partons(
double alpha_s, double mur,
std::vector<Particle> const & partons
) const;
std::vector<int> in_extremal_jet_indices(
std::vector<fastjet::PseudoJet> const & partons
) const;
std::vector<Particle> tag_extremal_jet_partons(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> out_partons, bool check_momenta
+ Event const & ev, bool check_momenta
) const;
double MH2_forwardH(
CLHEP::HepLorentzVector p1out, CLHEP::HepLorentzVector p1in,
pid::ParticleID type2,
CLHEP::HepLorentzVector p2out, CLHEP::HepLorentzVector p2in,
CLHEP::HepLorentzVector pH,
double t1, double t2
) const;
std::function<double (double)> alpha_s_;
MatrixElementConfig param_;
};
}
diff --git a/include/HEJ/Weights.hh b/include/HEJ/Weights.hh
new file mode 100644
index 0000000..fc92237
--- /dev/null
+++ b/include/HEJ/Weights.hh
@@ -0,0 +1,45 @@
+/** \file
+ * \brief Container for event weights
+ */
+#pragma once
+
+#include <vector>
+
+namespace HEJ{
+ //! Collection of weights assigned to a single event
+ /**
+ * A number of member functions of the MatrixElement class return Weights
+ * objects containing the squares of the matrix elements for the various
+ * scale choices.
+ */
+ struct Weights {
+ double central;
+ std::vector<double> variations;
+
+ Weights& operator*=(Weights const & other);
+ Weights& operator*=(double factor);
+ Weights& operator/=(Weights const & other);
+ Weights& operator/=(double factor);
+ };
+
+ inline
+ Weights operator*(Weights a, Weights const & b) {
+ return a*=b;
+ }
+ inline
+ Weights operator*(Weights a, double b) {
+ return a*=b;
+ }
+ inline
+ Weights operator*(double b, Weights a) {
+ return a*=b;
+ }
+ inline
+ Weights operator/(Weights a, Weights const & b) {
+ return a/=b;
+ }
+ inline
+ Weights operator/(Weights a, double b) {
+ return a/=b;
+ }
+}
diff --git a/include/HEJ/config.hh b/include/HEJ/config.hh
index a7fe397..7c51c05 100644
--- a/include/HEJ/config.hh
+++ b/include/HEJ/config.hh
@@ -1,175 +1,173 @@
/** \file
* \brief HEJ 2 configuration parameters
*/
#pragma once
#include <string>
#include <memory>
#include "fastjet/JetDefinition.hh"
#include "yaml-cpp/yaml.h"
#include "HEJ/event_types.hh"
#include "HEJ/Event.hh"
#include "HEJ/HiggsCouplingSettings.hh"
#include "HEJ/optional.hh"
#include "HEJ/output_formats.hh"
#include "HEJ/ScaleFunction.hh"
#include "HEJ/utility.hh"
namespace HEJ{
//! Jet parameters
struct JetParameters{
fastjet::JetDefinition def; /**< Jet Definition */
double min_pt; /**< Minimum Jet Transverse Momentum */
};
//! Settings for scale variation
struct ScaleConfig{
//! Base scale choices
std::vector<ScaleFunction> base;
//! Factors for multiplicative scale variation
std::vector<double> factors;
//! Maximum ratio between renormalisation and factorisation scale
double max_ratio;
};
//! Settings for random number generator
struct RNGConfig {
//! Random number generator name
std::string name;
//! Optional initial seed
optional<std::string> seed;
};
/**! Possible treatments for fixed-order input events.
*
* The program will decide on how to treat an event based on
* the value of this enumeration.
*/
enum class EventTreatment{
reweight, /**< Perform resummation */
keep, /**< Keep the event */
discard, /**< Discard the event */
};
//! Container to store the treatments for various event types
using EventTreatMap = std::map<event_type::EventType, EventTreatment>;
/**! Input parameters.
*
* This struct handles stores all configuration parameters
* needed in a HEJ 2 run.
*
* \internal To add a new option:
* 1. Add a member to the Config struct.
* 2. Inside "src/YAMLreader.cc":
* - Add the option name to the "supported" Node in
* get_supported_options.
* - Initialise the new Config member in to_Config.
* The functions set_from_yaml (for mandatory options) and
* set_from_yaml_if_defined (non-mandatory) may be helpful.
* 3. Add a new entry (with short description) to config.yaml
* 4. Update the user documentation in "doc/Sphinx/"
*/
struct Config {
//! Parameters for scale variation
ScaleConfig scales;
//! Resummation jet properties
JetParameters resummation_jets;
//! Fixed-order jet properties
JetParameters fixed_order_jets;
//! Minimum transverse momentum for extremal partons
double min_extparton_pt;
//! Maximum transverse momentum fraction from soft radiation in extremal jets
double max_ext_soft_pt_fraction;
//! Number of resummation configurations to generate per fixed-order event
int trials;
//! Whether to include the logarithmic correction from \f$\alpha_s\f$ running
bool log_correction;
//! Whether to perform unweighting
bool unweight;
//! Event output files names and formats
std::vector<OutputFile> output;
//! Parameters for random number generation
RNGConfig rng;
//! Map to decide what to do for different event types
EventTreatMap treat;
//! Parameters for custom analyses
YAML::Node analysis_parameters;
//! Settings for effective Higgs-gluon coupling
HiggsCouplingSettings Higgs_coupling;
};
//! Configuration options for the PhaseSpacePoint class
struct PhaseSpacePointConfig {
//! Properties of resummation jets
JetParameters jet_param;
//! Minimum transverse momentum for extremal partons
double min_extparton_pt;
//! Maximum transverse momentum fraction from soft radiation in extremal jets
double max_ext_soft_pt_fraction;
};
//! Configuration options for the MatrixElement class
struct MatrixElementConfig {
- //! Jet properties
- JetParameters jet_param;
//! Whether to include the logarithmic correction from \f$\alpha_s\f$ running
bool log_correction;
//! Settings for effective Higgs-gluon coupling
HiggsCouplingSettings Higgs_coupling;
};
//! Configuration options for the EventReweighter class
struct EventReweighterConfig {
//! Settings for phase space point generation
PhaseSpacePointConfig psp_config;
//! Settings for matrix element calculation
MatrixElementConfig ME_config;
//! Properties of resummation jets
JetParameters jet_param;
//! Treatment of the various event types
EventTreatMap treat;
};
/**! Extract PhaseSpacePointConfig from Config
*
* \internal We do not provide a PhaseSpacePointConfig constructor from Config
* so that PhaseSpacePointConfig remains an aggregate.
* This faciliates writing client code (e.g. the HEJ fixed-order generator)
* that creates a PhaseSpacePointConfig *without* a Config object.
*
* @see to_MatrixElementConfig, to_EventReweighterConfig
*/
inline
PhaseSpacePointConfig to_PhaseSpacePointConfig(Config const & conf) {
return {conf.resummation_jets, conf.min_extparton_pt, conf.max_ext_soft_pt_fraction};
}
/**! Extract MatrixElementConfig from Config
*
* @see to_PhaseSpacePointConfig, to_EventReweighterConfig
*/
inline
MatrixElementConfig to_MatrixElementConfig(Config const & conf) {
- return {conf.resummation_jets, conf.log_correction, conf.Higgs_coupling};
+ return {conf.log_correction, conf.Higgs_coupling};
}
/**! Extract EventReweighterConfig from Config
*
* @see to_PhaseSpacePointConfig, to_MatrixElementConfig
*/
inline
EventReweighterConfig to_EventReweighterConfig(Config const & conf) {
return {
to_PhaseSpacePointConfig(conf),
to_MatrixElementConfig(conf),
conf.resummation_jets, conf.treat
};
}
} // namespace HEJ
diff --git a/include/HEJ/event_types.hh b/include/HEJ/event_types.hh
index 16f1416..6cf3d82 100644
--- a/include/HEJ/event_types.hh
+++ b/include/HEJ/event_types.hh
@@ -1,42 +1,60 @@
/** \file
* \brief Define different types of events.
*
*/
#pragma once
#include "HEJ/utility.hh"
namespace HEJ{
//! Namespace for event types
namespace event_type{
//! Possible event types
enum EventType: size_t{
FKL, /**< FKL-type event */
unordered_backward, /**< event with unordered backward emission */
unordered_forward, /**< event with unordered forward emission */
nonHEJ, /**< event configuration not covered by HEJ */
no_2_jets, /**< event with less than two jets */
bad_final_state, /**< event with an unsupported final state */
unob = unordered_backward,
unof = unordered_forward,
first_type = FKL,
last_type = bad_final_state
};
//! Event type names
/**
* For example, names[FKL] is the string "FKL"
*/
static constexpr auto names = make_array(
"FKL",
"unordered backward",
"unordered forward",
"nonHEJ",
"no 2 jets",
"bad final state"
);
+
+ inline
+ bool is_HEJ(EventType type) {
+ switch(type) {
+ case FKL:
+ case unordered_backward:
+ case unordered_forward:
+ return true;
+ default:
+ return false;
+ }
+ }
+
+ inline
+ bool is_uno(EventType type) {
+ return type == unordered_backward || type == unordered_forward;
+ }
+
}
}
diff --git a/include/HEJ/uno.hh b/include/HEJ/uno.hh
deleted file mode 100644
index 289a556..0000000
--- a/include/HEJ/uno.hh
+++ /dev/null
@@ -1,65 +0,0 @@
-/** \file uno.hh
- * \brief Functions for determining if event is unordered.
- */
-
-#pragma once
-
-#include "HEJ/utility.hh"
-#include "HEJ/PDG_codes.hh"
-
-namespace HEJ{
- //! Check if an event has an unordered backward gluon emission
- /**
- * @param incoming Incoming particles in ascending pz
- * @param outgoing Outgoing particles in ascending rapidity
- * @returns true iff the most backward outgoing particle is a
- * gluon and the first incoming particle is not a gluon.
- *
- * If the incoming and outgoing particles are ordered such that HEJ resummation
- * is possible, this function can help to distinguish between FKL and unordered
- * events.
- */
- inline
- bool has_unob_gluon(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing
- ){
- return incoming.front().type != pid::gluon
- && outgoing.front().type == pid::gluon;
- }
-
-
- //! Check if an event has an unordered backward gluon emission
- /**
- * @param incoming Incoming particles in ascending pz
- * @param outgoing Outgoing particles in ascending rapidity
- * @returns true iff the most forward outgoing particle is a
- * gluon and the last incoming particle is not a gluon.
- *
- * If the incoming and outgoing particles are ordered such that HEJ resummation
- * is possible, this function can help to distinguish between FKL and unordered
- * events.
- */
- inline
- bool has_unof_gluon(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing
- ){
- return incoming.back().type != pid::gluon
- && outgoing.back().type == pid::gluon;
- }
-
- //! Check if an event has an gluon emission
- /**
- * @see has_unob_gluon, has_unof_gluon
- */
- inline
- bool has_uno_gluon(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing
- ){
- return
- has_unob_gluon(incoming, outgoing) || has_unof_gluon(incoming, outgoing);
- }
-
-}
diff --git a/src/Event.cc b/src/Event.cc
index f098930..6dc344f 100644
--- a/src/Event.cc
+++ b/src/Event.cc
@@ -1,343 +1,341 @@
#include "HEJ/Event.hh"
#include "HEJ/utility.hh"
namespace HEJ{
namespace{
constexpr int status_in = -1;
constexpr int status_decayed = 2;
constexpr int status_out = 1;
- // helper functions to determine event type
+ /// @name helper functions to determine event type
+ //@{
- // check if there is at most one photon, W, H, Z in the final state
- // and all the rest are quarks or gluons
+ /**
+ * \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!
+ /// @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
+ * - 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){
return Particle{
static_cast<ParticleID>(hepeup.IDUP[i]),
fastjet::PseudoJet{
hepeup.PUP[i][0], hepeup.PUP[i][1],
hepeup.PUP[i][2], hepeup.PUP[i][3]
}
};
}
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));
}
std::sort(
begin(incoming), end(incoming),
[](Particle o1, Particle o2){return o1.p.pz()<o2.p.pz();}
);
std::sort(begin(outgoing), end(outgoing), rapidity_less{});
// 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));
}
}
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}
{
type_ = classify(*this);
}
std::vector<fastjet::PseudoJet> Event::jets() const{
return cs_.inclusive_jets(min_jet_pt_);
}
- /**
- * \brief Returns the invarient mass of the event
- * @param ev Event
- * @returns s hat
- *
- * Makes use of the FastJet PseudoJet function m2().
- * Applies this function to the sum of the incoming partons.
- */
double shat(Event const & ev){
return (ev.incoming()[0].p + ev.incoming()[1].p).m2();
}
namespace{
// colour flow according to Les Houches standard
// TODO: stub
std::vector<std::pair<int, int>> colour_flow(
std::array<Particle, 2> const & incoming,
std::vector<Particle> const & outgoing
){
std::vector<std::pair<int, int>> result(
incoming.size() + outgoing.size()
);
for(auto & col: result){
col = std::make_pair(-1, -1);
}
return result;
}
}
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;
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);
}
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);
}
result.ICOLUP = colour_flow(
event.incoming(), filter_partons(event.outgoing())
);
if(result.ICOLUP.size() < num_particles){
const size_t AWZH_boson_idx = std::find_if(
begin(event.outgoing()), end(event.outgoing()),
[](Particle const & s){ return is_AWZH_boson(s); }
) - begin(event.outgoing()) + event.incoming().size();
assert(AWZH_boson_idx <= result.ICOLUP.size());
result.ICOLUP.insert(
begin(result.ICOLUP) + AWZH_boson_idx,
std::make_pair(0,0)
);
}
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;
}
}
diff --git a/src/EventReweighter.cc b/src/EventReweighter.cc
index 7687fb2..72e1f6d 100644
--- a/src/EventReweighter.cc
+++ b/src/EventReweighter.cc
@@ -1,343 +1,259 @@
#include "HEJ/EventReweighter.hh"
#include <string>
#include <unordered_map>
+#include "HEJ/exceptions.hh"
#include "HEJ/PhaseSpacePoint.hh"
#include "HEJ/PDG_codes.hh"
#include "HEJ/utility.hh"
namespace HEJ{
using EventType = event_type::EventType;
namespace {
static_assert(
std::numeric_limits<double>::has_quiet_NaN,
"no quiet NaN for double"
);
constexpr double NaN = std::numeric_limits<double>::quiet_NaN();
UnclusteredEvent to_UnclusteredEvent(PhaseSpacePoint const & psp){
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),
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 anonymous
EventReweighter::EventReweighter(
LHEF::HEPRUP const & heprup,
ScaleGenerator scale_gen,
EventReweighterConfig conf,
HEJ::RNG & ran
):
EventReweighter{
HEJ::Beam{
heprup.EBMUP.first,
{{
static_cast<HEJ::ParticleID>(heprup.IDBMUP.first),
static_cast<HEJ::ParticleID>(heprup.IDBMUP.second)
}}
},
heprup.PDFSUP.first,
std::move(scale_gen),
std::move(conf),
ran
}
{
if(heprup.EBMUP.second != E_beam_){
throw std::invalid_argument(
"asymmetric beam: " + std::to_string(E_beam_)
+ " ---> <--- " + std::to_string(heprup.EBMUP.second)
);
};
if(heprup.PDFSUP.second != pdf_.id()){
throw std::invalid_argument(
"conflicting PDF ids: " + std::to_string(pdf_.id())
+ " vs. " + std::to_string(heprup.PDFSUP.second)
);
}
}
EventReweighter::EventReweighter(
Beam beam,
int pdf_id,
ScaleGenerator scale_gen,
EventReweighterConfig conf,
HEJ::RNG & ran
):
param_{std::move(conf)},
E_beam_{beam.E},
pdf_{pdf_id, beam.type.front(), beam.type.back()},
MEt2_{
[this](double mu){ return pdf_.Halphas(mu); },
param_.ME_config
},
scale_gen_(std::move(scale_gen)),
ran_{ran}
{}
PDF const & EventReweighter::pdf() const{
return pdf_;
}
std::vector<Event> EventReweighter::reweight(
Event const & input_ev, int num_events
){
auto res_events = gen_res_events(input_ev, num_events);
if(res_events.empty()) return {};
for(auto & event: res_events) event = scale_gen_(event);
return rescale(input_ev, std::move(res_events));
}
- /**
- * \brief main generation/reweighting function:
- * generate phase space points and divide out Born factors
- */
std::vector<Event> EventReweighter::gen_res_events(
Event const & ev,
int phase_space_points
){
assert(ev.variations().empty());
switch(param_.treat.at(ev.type())){
case EventTreatment::discard: return {};
case EventTreatment::keep:
if(! jets_pass_resummation_cuts(ev)) return {};
else return {ev};
default:;
}
const double Born_shat = shat(ev);
std::vector<Event> resummation_events;
for(int psp_number = 0; psp_number < phase_space_points; ++psp_number){
PhaseSpacePoint psp{ev, param_.psp_config, ran_};
if(psp.weight() == 0.) continue;
if(psp.incoming()[0].E() > E_beam_ || psp.incoming()[1].E() > E_beam_) continue;
resummation_events.emplace_back(
to_UnclusteredEvent(std::move(psp)),
param_.jet_param.def, param_.jet_param.min_pt
);
auto & new_event = resummation_events.back();
assert(new_event.variations().empty());
new_event.central().mur = ev.central().mur;
new_event.central().muf = ev.central().muf;
const double resum_shat = shat(new_event);
new_event.central().weight *= ev.central().weight*Born_shat*Born_shat/
(phase_space_points*resum_shat*resum_shat);
}
return resummation_events;
}
std::vector<Event> EventReweighter::rescale(
Event const & Born_ev,
std::vector<Event> events
) const{
const double Born_pdf = pdf_factors(Born_ev).central;
const double Born_ME = tree_matrix_element(Born_ev);
for(auto & cur_event: events){
const auto pdf = pdf_factors(cur_event);
assert(pdf.variations.size() == cur_event.variations().size());
const auto ME = matrix_elements(cur_event);
assert(ME.variations.size() == cur_event.variations().size());
cur_event.central().weight *= pdf.central*ME.central/(Born_pdf*Born_ME);
for(size_t i = 0; i < cur_event.variations().size(); ++i){
cur_event.variations(i).weight *=
pdf.variations[i]*ME.variations[i]/(Born_pdf*Born_ME);
}
}
return events;
};
- /**
- * \brief Do the Jets pass the resummation Cuts?
- *
- * @param ev Event in Question
- * @returns 0 or 1 depending on if ev passes Jet Cuts
- */
bool EventReweighter::jets_pass_resummation_cuts(
Event const & ev
) const{
const auto out_as_PseudoJet = to_PseudoJet(filter_partons(ev.outgoing()));
fastjet::ClusterSequence cs{out_as_PseudoJet, param_.jet_param.def};
return cs.inclusive_jets(param_.jet_param.min_pt).size() == ev.jets().size();
}
-
-
- /**
- * \brief pdf_factors Function
- *
- * @param ev Event in Question
- * @returns EventFactor due to PDFs
- *
- * Calculates the Central value and the variation due
- * to the PDF choice made.
- */
- EventReweighter::EventFactors
+ Weights
EventReweighter::pdf_factors(Event const & ev) const{
auto const & a = ev.incoming().front();
auto const & b = ev.incoming().back();
const double xa = a.p.e()/E_beam_;
const double xb = b.p.e()/E_beam_;
- EventFactors result;
+ Weights result;
std::unordered_map<double, double> known_pdf;
result.central =
pdf_.pdfpt(0,xa,ev.central().muf,a.type)*
pdf_.pdfpt(1,xb,ev.central().muf,b.type);
known_pdf.emplace(ev.central().muf, result.central);
result.variations.reserve(ev.variations().size());
for(auto const & ev_param: ev.variations()){
const double muf = ev_param.muf;
auto cur_pdf = known_pdf.find(muf);
if(cur_pdf == known_pdf.end()){
cur_pdf = known_pdf.emplace(
muf,
pdf_.pdfpt(0,xa,muf,a.type)*pdf_.pdfpt(1,xb,muf,b.type)
).first;
}
result.variations.emplace_back(cur_pdf->second);
}
assert(result.variations.size() == ev.variations().size());
return result;
}
-
-
- /**
- * \brief matrix_elements Function
- *
- * @param ev Event in question
- * @returns EventFactor due to MatrixElements
- *
- * Calculates the Central value and the variation due
- * to the Matrix Element.
- */
- EventReweighter::EventFactors
+ Weights
EventReweighter::matrix_elements(Event const & ev) const{
assert(param_.treat.count(ev.type()) > 0);
if(param_.treat.find(ev.type())->second == EventTreatment::keep){
return fixed_order_scale_ME(ev);
}
- // precompute overall kinematic factor
- const double ME_kin = MEt2_.tree_kin(ev.incoming(), ev.outgoing(), true);
-
- EventFactors result;
- std::unordered_map<double, double> known_ME;
- result.central = MEt2_(
- ev.central().mur,
- ev.incoming(), ev.outgoing(),
- true
- );
- known_ME.emplace(ev.central().mur, result.central);
-
- result.variations.reserve(ev.variations().size());
- for(auto const & param: ev.variations()){
- const double mur = param.mur;
- auto cur_ME = known_ME.find(mur);
- if(cur_ME == known_ME.end()){
- const double ME = MEt2_.tree_param(
- mur, ev.incoming(), ev.outgoing()
- )*ME_kin*MEt2_.virtual_corrections(
- mur, ev.incoming(), ev.outgoing()
- );
- cur_ME = known_ME.emplace(mur, ME).first;
- }
- result.variations.emplace_back(cur_ME->second);
- }
- assert(result.variations.size() == ev.variations().size());
- return result;
+ return MEt2_(ev, true);
}
- /**
- * \brief Computes the tree level matrix element
- *
- * @param ev Event in Question
- * @returns HEJ approximation to Tree level Matrix Element
- *
- * This computes the HEJ approximation to the tree level FO
- * Matrix element which is used within the LO weighting process.
- */
double EventReweighter::tree_matrix_element(Event const & ev) const{
assert(ev.variations().empty());
assert(param_.treat.count(ev.type()) > 0);
if(param_.treat.find(ev.type())->second == EventTreatment::keep){
return fixed_order_scale_ME(ev).central;
}
- return MEt2_.tree(
- ev.central().mur,
- ev.incoming(), ev.outgoing(),
- false
- );
+ return MEt2_.tree(ev, false).central;
}
- /**
- * \brief Scale-dependent part of fixed-order matrix element
- *
- * @param ev Event in question
- * @returns EventFactor scale variation due to FO-ME.
- *
- * This is only called to compute the scale variation for events where
- * we don't do resummation (e.g. non-FKL).
- * Since at tree level the scale dependence is just due to alpha_s,
- * it is enough to return the alpha_s(mur) factors in the matrix element.
- * The rest drops out in the ratio of (output event ME)/(input event ME),
- * so we never have to compute it.
- */
- EventReweighter::EventFactors
+ Weights
EventReweighter::fixed_order_scale_ME(Event const & ev) const{
int alpha_s_power = 0;
for(auto const & part: ev.outgoing()){
if(is_parton(part))
++alpha_s_power;
else {
switch(part.type){
case pid::Higgs: {
alpha_s_power += 2;
break;
}
// TODO
case pid::Wp:
case pid::Wm:
case pid::photon:
case pid::Z:
default:
- throw std::logic_error("Emission of boson of unsupported type");
+ throw not_implemented("Emission of boson of unsupported type");
}
}
}
- EventFactors result;
+ Weights result;
result.central = pow(pdf_.Halphas(ev.central().mur), alpha_s_power);
for(auto const & var: ev.variations()){
result.variations.emplace_back(
pow(pdf_.Halphas(var.mur), alpha_s_power)
);
}
return result;
}
} // namespace HEJ
diff --git a/src/MatrixElement.cc b/src/MatrixElement.cc
index e9c644d..5d31d30 100644
--- a/src/MatrixElement.cc
+++ b/src/MatrixElement.cc
@@ -1,826 +1,860 @@
#include "HEJ/MatrixElement.hh"
+#include <unordered_map>
+
#include <CLHEP/Random/Randomize.h>
#include <CLHEP/Random/RanluxEngine.h>
#include "HEJ/Constants.hh"
#include "HEJ/currents.hh"
#include "HEJ/exceptions.hh"
#include "HEJ/PDG_codes.hh"
-#include "HEJ/uno.hh"
+#include "HEJ/event_types.hh"
#include "HEJ/utility.hh"
namespace HEJ{
//cf. last line of eq. (22) in \ref Andersen:2011hs
double MatrixElement::omega0(
double alpha_s, double mur,
fastjet::PseudoJet const & q_j, double lambda
) const {
const double result = - alpha_s*N_C/M_PI*log(q_j.perp2()/(lambda*lambda));
if(! param_.log_correction) return result;
// use alpha_s(sqrt(q_j*lambda)), evolved to mur
return (
1. + alpha_s/(4.*M_PI)*beta0*log(mur*mur/(q_j.perp()*lambda))
)*result;
}
+ Weights MatrixElement::operator()(
+ Event const & event,
+ bool check_momenta
+ ) const {
+ return tree(event, check_momenta)*virtual_corrections(event);
+ }
+
+ Weights MatrixElement::tree(
+ Event const & event,
+ bool check_momenta
+ ) const {
+ if(! is_HEJ(event.type())) {
+ return Weights{0., std::vector<double>(event.variations().size(), 0.)};
+ }
+ return tree_param(event)*tree_kin(event, check_momenta);
+ }
+
+ Weights MatrixElement::tree_param(
+ Event const & event
+ ) const {
+ Weights result;
+ // only compute once for each renormalisation scale
+ std::unordered_map<double, double> known;
+ result.central = tree_param(event, event.central().mur);
+ known.emplace(event.central().mur, result.central);
+ for(auto const & var: event.variations()) {
+ const auto ME_it = known.find(var.mur);
+ if(ME_it == end(known)) {
+ const double wt = tree_param(event, var.mur);
+ result.variations.emplace_back(wt);
+ known.emplace(var.mur, wt);
+ }
+ else {
+ result.variations.emplace_back(ME_it->second);
+ }
+ }
+ return result;
+ }
+
+ Weights MatrixElement::virtual_corrections(
+ Event const & event
+ ) const {
+ if(! is_HEJ(event.type())) {
+ return Weights{0., std::vector<double>(event.variations().size(), 0.)};
+ }
+ Weights result;
+ // only compute once for each renormalisation scale
+ std::unordered_map<double, double> known;
+ result.central = virtual_corrections(event, event.central().mur);
+ known.emplace(event.central().mur, result.central);
+ for(auto const & var: event.variations()) {
+ const auto ME_it = known.find(var.mur);
+ if(ME_it == end(known)) {
+ const double wt = virtual_corrections(event, var.mur);
+ result.variations.emplace_back(wt);
+ known.emplace(var.mur, wt);
+ }
+ else {
+ result.variations.emplace_back(ME_it->second);
+ }
+ }
+ return result;
+ }
+
double MatrixElement::virtual_corrections(
- double mur,
- std::array<Particle, 2> const & in,
- std::vector<Particle> const & out
+ Event const & event,
+ double mur
) const{
+ auto const & in = event.incoming();
+ auto const & out = event.outgoing();
fastjet::PseudoJet const & pa = in.front().p;
#ifndef NDEBUG
fastjet::PseudoJet const & pb = in.back().p;
double const norm = (in.front().p + in.back().p).E();
#endif
assert(std::is_sorted(out.begin(), out.end(), rapidity_less{}));
assert(out.size() >= 2);
assert(pa.pz() < pb.pz());
fastjet::PseudoJet q = pa - out[0].p;
size_t first_idx = 0;
size_t last_idx = out.size() - 1;
// if there is a Higgs or unordered gluon outside the extremal partons
// then it is not part of the FKL ladder and does not contribute
// to the virtual corrections
- if(out.front().type == pid::Higgs || has_unob_gluon(in, out)){
+ if(out.front().type == pid::Higgs || event.type() == event_type::unob){
q -= out[1].p;
++first_idx;
}
- if(out.back().type == pid::Higgs || has_unof_gluon(in, out)){
+ if(out.back().type == pid::Higgs || event.type() == event_type::unof){
--last_idx;
}
double exponent = 0;
const double alpha_s = alpha_s_(mur);
for(size_t j = first_idx; j < last_idx; ++j){
exponent += omega0(alpha_s, mur, q, CLAMBDA)*(
out[j+1].rapidity() - out[j].rapidity()
);
q -= out[j+1].p;
}
assert(
nearby(q, -1*pb, norm)
|| out.back().type == pid::Higgs
- || has_unof_gluon(in, out)
+ || event.type() == event_type::unof
);
return exp(exponent);
}
} // namespace HEJ
namespace {
//! Lipatov vertex for partons emitted into extremal jets
double C2Lipatov(CLHEP::HepLorentzVector qav, CLHEP::HepLorentzVector qbv,
CLHEP::HepLorentzVector p1, CLHEP::HepLorentzVector p2)
{
CLHEP::HepLorentzVector temptrans=-(qav+qbv);
CLHEP::HepLorentzVector p5=qav-qbv;
CLHEP::HepLorentzVector CL=temptrans
+ p1*(qav.m2()/p5.dot(p1) + 2.*p5.dot(p2)/p1.dot(p2))
- p2*(qbv.m2()/p5.dot(p2) + 2.*p5.dot(p1)/p1.dot(p2));
// cout << "#Fadin qa : "<<qav<<endl;
// cout << "#Fadin qb : "<<qbv<<endl;
// cout << "#Fadin p1 : "<<p1<<endl;
// cout << "#Fadin p2 : "<<p2<<endl;
// cout << "#Fadin p5 : "<<p5<<endl;
// cout << "#Fadin Gauge Check : "<< CL.dot(p5)<<endl;
// cout << "#Fadin C2L : "<< -CL.dot(CL)<<" "<<-CL.dot(CL)/(qav.m2()*qbv.m2())/(4./p5.perp2())<<endl;
// TODO can this dead test go?
// if (-CL.dot(CL)<0.)
// if (fabs(CL.dot(p5))>fabs(CL.dot(CL))) // not sufficient!
// return 0.;
// else
return -CL.dot(CL);
}
//! Lipatov vertex with soft subtraction for partons emitted into extremal jets
double C2Lipatovots(CLHEP::HepLorentzVector qav, CLHEP::HepLorentzVector qbv,
CLHEP::HepLorentzVector p1, CLHEP::HepLorentzVector p2)
{
double kperp=(qav-qbv).perp();
if (kperp>HEJ::CLAMBDA)
return C2Lipatov(qav, qbv, p1, p2)/(qav.m2()*qbv.m2());
else {
double Cls=(C2Lipatov(qav, qbv, p1, p2)/(qav.m2()*qbv.m2()));
return Cls-4./(kperp*kperp);
}
}
//! Lipatov vertex
double C2Lipatov(CLHEP::HepLorentzVector qav, CLHEP::HepLorentzVector qbv,
CLHEP::HepLorentzVector pim, CLHEP::HepLorentzVector pip,
CLHEP::HepLorentzVector pom, CLHEP::HepLorentzVector pop) // B
{
CLHEP::HepLorentzVector temptrans=-(qav+qbv);
CLHEP::HepLorentzVector p5=qav-qbv;
CLHEP::HepLorentzVector CL=temptrans
+ qav.m2()*(1./p5.dot(pip)*pip + 1./p5.dot(pop)*pop)/2.
- qbv.m2()*(1./p5.dot(pim)*pim + 1./p5.dot(pom)*pom)/2.
+ ( pip*(p5.dot(pim)/pip.dot(pim) + p5.dot(pom)/pip.dot(pom))
+ pop*(p5.dot(pim)/pop.dot(pim) + p5.dot(pom)/pop.dot(pom))
- pim*(p5.dot(pip)/pip.dot(pim) + p5.dot(pop)/pop.dot(pim))
- pom*(p5.dot(pip)/pip.dot(pom) + p5.dot(pop)/pop.dot(pom)) )/2.;
return -CL.dot(CL);
}
//! Lipatov vertex with soft subtraction
double C2Lipatovots(CLHEP::HepLorentzVector qav, CLHEP::HepLorentzVector qbv,
CLHEP::HepLorentzVector pa, CLHEP::HepLorentzVector pb,
CLHEP::HepLorentzVector p1, CLHEP::HepLorentzVector p2)
{
double kperp=(qav-qbv).perp();
if (kperp>HEJ::CLAMBDA)
return C2Lipatov(qav, qbv, pa, pb, p1, p2)/(qav.m2()*qbv.m2());
else {
double Cls=(C2Lipatov(qav, qbv, pa, pb, p1, p2)/(qav.m2()*qbv.m2()));
double temp=Cls-4./(kperp*kperp);
return temp;
}
}
/** Matrix element squared for tree-level current-current scattering
* @param aptype Particle a PDG ID
* @param bptype Particle b PDG ID
* @param pn Particle n Momentum
* @param pb Particle b Momentum
* @param p1 Particle 1 Momentum
* @param pa Particle a Momentum
* @returns ME Squared for Tree-Level Current-Current Scattering
*/
double ME_current(
int aptype, int bptype,
CLHEP::HepLorentzVector const & pn,
CLHEP::HepLorentzVector const & pb,
CLHEP::HepLorentzVector const & p1,
CLHEP::HepLorentzVector const & pa
){
if (aptype==21&&bptype==21) {
return jM2gg(pn,pb,p1,pa);
} else if (aptype==21&&bptype!=21) {
if (bptype > 0)
return jM2qg(pn,pb,p1,pa);
else
return jM2qbarg(pn,pb,p1,pa);
}
else if (bptype==21&&aptype!=21) { // ----- || -----
if (aptype > 0)
return jM2qg(p1,pa,pn,pb);
else
return jM2qbarg(p1,pa,pn,pb);
}
else { // they are both quark
if (bptype>0) {
if (aptype>0)
return jM2qQ(pn,pb,p1,pa);
else
return jM2qQbar(pn,pb,p1,pa);
}
else {
if (aptype>0)
return jM2qQbar(p1,pa,pn,pb);
else
return jM2qbarQbar(pn,pb,p1,pa);
}
}
throw std::logic_error("unknown particle types");
}
/** \brief Matrix element squared for tree-level current-current scattering with Higgs
* @param aptype Particle a PDG ID
* @param bptype Particle b PDG ID
* @param pn Particle n Momentum
* @param pb Particle b Momentum
* @param p1 Particle 1 Momentum
* @param pa Particle a Momentum
* @param qH t-channel momentum before Higgs
* @param qHp1 t-channel momentum after Higgs
* @returns ME Squared for Tree-Level Current-Current Scattering with Higgs
*/
double ME_Higgs_current(
int aptype, int bptype,
CLHEP::HepLorentzVector const & pn,
CLHEP::HepLorentzVector const & pb,
CLHEP::HepLorentzVector const & p1,
CLHEP::HepLorentzVector const & pa,
CLHEP::HepLorentzVector const & qH, // t-channel momentum before Higgs
CLHEP::HepLorentzVector const & qHp1, // t-channel momentum after Higgs
double mt, bool include_bottom, double mb
){
if (aptype==21&&bptype==21) // gg initial state
return MH2gg(pn,pb,p1,pa,-qHp1,-qH,mt,include_bottom,mb);
else if (aptype==21&&bptype!=21) {
if (bptype > 0)
return MH2qg(pn,pb,p1,pa,-qHp1,-qH,mt,include_bottom,mb)*4./9.;
else
return MH2qbarg(pn,pb,p1,pa,-qHp1,-qH,mt,include_bottom,mb)*4./9.;
}
else if (bptype==21&&aptype!=21) {
if (aptype > 0)
return MH2qg(p1,pa,pn,pb,-qH,-qHp1,mt,include_bottom,mb)*4./9.;
else
return MH2qbarg(p1,pa,pn,pb,-qH,-qHp1,mt,include_bottom,mb)*4./9.;
}
else { // they are both quark
if (bptype>0) {
if (aptype>0)
return MH2qQ(pn,pb,p1,pa,-qHp1,-qH,mt,include_bottom,mb)*4.*4./(9.*9.);
else
return MH2qQbar(pn,pb,p1,pa,-qHp1,-qH,mt,include_bottom,mb)*4.*4./(9.*9.);
}
else {
if (aptype>0)
return MH2qQbar(p1,pa,pn,pb,-qH,-qHp1,mt,include_bottom,mb)*4.*4./(9.*9.);
else
return MH2qbarQbar(pn,pb,p1,pa,-qHp1,-qH,mt,include_bottom,mb)*4.*4./(9.*9.);
}
}
throw std::logic_error("unknown particle types");
}
/** \brief Current matrix element squared with Higgs and unordered forward emission
* @param aptype Particle A PDG ID
* @param bptype Particle B PDG ID
* @param punof Unordered Particle Momentum
* @param pn Particle n Momentum
* @param pb Particle b Momentum
* @param p1 Particle 1 Momentum
* @param pa Particle a Momentum
* @param qH t-channel momentum before Higgs
* @param qHp1 t-channel momentum after Higgs
* @returns ME Squared with Higgs and unordered forward emission
*/
double ME_Higgs_current_unof(
int aptype, int bptype,
CLHEP::HepLorentzVector const & punof,
CLHEP::HepLorentzVector const & pn,
CLHEP::HepLorentzVector const & pb,
CLHEP::HepLorentzVector const & p1,
CLHEP::HepLorentzVector const & pa,
CLHEP::HepLorentzVector const & qH, // t-channel momentum before Higgs
CLHEP::HepLorentzVector const & qHp1, // t-channel momentum after Higgs
double mt, bool include_bottom, double mb
){
if (aptype==21&&bptype!=21) {
if (bptype > 0)
return jM2unogqHg(punof,pn,pb,p1,pa,-qHp1,-qH,mt,include_bottom,mb);
else
return jM2unogqbarHg(punof,pn,pb,p1,pa,-qHp1,-qH,mt,include_bottom,mb);
}
else { // they are both quark
if (bptype>0) {
if (aptype>0)
return jM2unogqHQ(punof,pn,pb,p1,pa,-qHp1,-qH,mt,include_bottom,mb);
else
return jM2unogqHQbar(punof,pn,pb,p1,pa,-qHp1,-qH,mt,include_bottom,mb);
}
else {
if (aptype>0)
return jM2unogqbarHQ(punof,pn,pb,p1,pa,-qHp1,-qH,mt,include_bottom,mb);
else
return jM2unogqbarHQbar(punof,pn,pb,p1,pa,-qHp1,-qH,mt,include_bottom,mb);
}
}
throw std::logic_error("unknown particle types");
}
/** \brief Current matrix element squared with Higgs and unordered backward emission
* @param aptype Particle A PDG ID
* @param bptype Particle B PDG ID
* @param pn Particle n Momentum
* @param pb Particle b Momentum
* @param punob Unordered back Particle Momentum
* @param p1 Particle 1 Momentum
* @param pa Particle a Momentum
* @param qH t-channel momentum before Higgs
* @param qHp1 t-channel momentum after Higgs
* @returns ME Squared with Higgs and unordered backward emission
*/
double ME_Higgs_current_unob(
int aptype, int bptype,
CLHEP::HepLorentzVector const & pn,
CLHEP::HepLorentzVector const & pb,
CLHEP::HepLorentzVector const & punob,
CLHEP::HepLorentzVector const & p1,
CLHEP::HepLorentzVector const & pa,
CLHEP::HepLorentzVector const & qH, // t-channel momentum before Higgs
CLHEP::HepLorentzVector const & qHp1, // t-channel momentum after Higgs
double mt, bool include_bottom, double mb
){
if (bptype==21&&aptype!=21) {
if (aptype > 0)
return jM2unobgHQg(pn,pb,punob,p1,pa,-qHp1,-qH,mt,include_bottom,mb);
else
return jM2unobgHQbarg(pn,pb,punob,p1,pa,-qHp1,-qH,mt,include_bottom,mb);
}
else { // they are both quark
if (aptype>0) {
if (bptype>0)
return jM2unobqHQg(pn,pb,punob,p1,pa,-qHp1,-qH,mt,include_bottom,mb);
else
return jM2unobqbarHQg(pn,pb,punob,p1,pa,-qHp1,-qH,mt,include_bottom,mb);
}
else {
if (bptype>0)
return jM2unobqHQbarg(pn,pb,punob,p1,pa,-qHp1,-qH,mt,include_bottom,mb);
else
return jM2unobqbarHQbarg(pn,pb,punob,p1,pa,-qHp1,-qH,mt,include_bottom,mb);
}
}
throw std::logic_error("unknown particle types");
}
CLHEP::HepLorentzVector to_HepLorentzVector(HEJ::Particle const & particle){
return {particle.p.px(), particle.p.py(), particle.p.pz(), particle.p.E()};
}
void validate(HEJ::MatrixElementConfig const & config) {
#ifndef HEJ_BUILD_WITH_QCDLOOP
if(!config.Higgs_coupling.use_impact_factors) {
throw std::invalid_argument{
"Invalid Higgs coupling settings.\n"
"HEJ without QCDloop support can only use impact factors.\n"
"Set use_impact_factors to true or recompile HEJ.\n"
};
}
#endif
if(config.Higgs_coupling.use_impact_factors
&& config.Higgs_coupling.mt != std::numeric_limits<double>::infinity()) {
throw std::invalid_argument{
"Conflicting settings: "
"impact factors may only be used in the infinite top mass limit"
};
}
}
} // namespace anonymous
namespace HEJ{
MatrixElement::MatrixElement(
std::function<double (double)> alpha_s,
MatrixElementConfig conf
):
alpha_s_{std::move(alpha_s)},
param_{std::move(conf)}
{
validate(param_);
}
- double MatrixElement::operator()(
- double mur,
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing,
- bool check_momenta
- ) const {
- return tree(
- mur,
- incoming, outgoing,
- check_momenta
- )*virtual_corrections(
- mur,
- incoming, outgoing
- );
- }
-
double MatrixElement::tree_kin(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing,
+ Event const & ev,
bool check_momenta
) const {
- assert(
- std::is_sorted(
- incoming.begin(), incoming.end(),
- [](Particle o1, Particle o2){return o1.p.pz()<o2.p.pz();}
- )
- );
- assert(std::is_sorted(outgoing.begin(), outgoing.end(), rapidity_less{}));
auto AWZH_boson = std::find_if(
- begin(outgoing), end(outgoing),
+ begin(ev.outgoing()), end(ev.outgoing()),
[](Particle const & p){return is_AWZH_boson(p);}
);
- if(AWZH_boson == end(outgoing)){
- return tree_kin_jets(incoming, outgoing, check_momenta);
+ if(AWZH_boson == end(ev.outgoing())){
+ return tree_kin_jets(ev, check_momenta);
}
switch(AWZH_boson->type){
case pid::Higgs: {
- return tree_kin_Higgs(incoming, outgoing, check_momenta);
+ return tree_kin_Higgs(ev, check_momenta);
}
// TODO
case pid::Wp:
case pid::Wm:
case pid::photon:
case pid::Z:
default:
- throw std::logic_error("Emission of boson of unsupported type");
+ throw not_implemented("Emission of boson of unsupported type");
}
}
namespace{
constexpr int extremal_jet_idx = 1;
constexpr int no_extremal_jet_idx = 0;
bool treat_as_extremal(Particle const & parton){
return parton.p.user_index() == extremal_jet_idx;
}
template<class InputIterator>
double FKL_ladder_weight(
InputIterator begin_gluon, InputIterator end_gluon,
CLHEP::HepLorentzVector const & q0,
CLHEP::HepLorentzVector const & pa, CLHEP::HepLorentzVector const & pb,
CLHEP::HepLorentzVector const & p1, CLHEP::HepLorentzVector const & pn
){
double wt = 1;
auto qi = q0;
for(auto gluon_it = begin_gluon; gluon_it != end_gluon; ++gluon_it){
assert(gluon_it->type == pid::gluon);
const auto g = to_HepLorentzVector(*gluon_it);
const auto qip1 = qi - g;
if(treat_as_extremal(*gluon_it)){
wt *= C2Lipatovots(qip1, qi, pa, pb)*C_A;
} else{
wt *= C2Lipatovots(qip1, qi, pa, pb, p1, pn)*C_A;
}
qi = qip1;
}
return wt;
}
} // namespace anonymous
std::vector<Particle> MatrixElement::tag_extremal_jet_partons(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> out_partons, bool check_momenta
+ Event const & ev, bool check_momenta
) const{
+ auto out_partons = filter_partons(ev.outgoing());
if(!check_momenta){
for(auto & parton: out_partons){
parton.p.set_user_index(no_extremal_jet_idx);
}
return out_partons;
}
- fastjet::ClusterSequence cs(to_PseudoJet(out_partons), param_.jet_param.def);
- const auto jets = sorted_by_rapidity(cs.inclusive_jets(param_.jet_param.min_pt));
+ // TODO: avoid reclustering
+ fastjet::ClusterSequence cs(to_PseudoJet(out_partons), ev.jet_def());
+ const auto jets = sorted_by_rapidity(cs.inclusive_jets(ev.min_jet_pt()));
assert(jets.size() >= 2);
auto most_backward = begin(jets);
auto most_forward = end(jets) - 1;
// skip jets caused by unordered emission
- if(has_unob_gluon(incoming, out_partons)){
+ if(ev.type() == event_type::unob){
assert(jets.size() >= 3);
++most_backward;
}
- else if(has_unof_gluon(incoming, out_partons)){
+ else if(ev.type() == event_type::unof){
assert(jets.size() >= 3);
--most_forward;
}
const auto extremal_jet_indices = cs.particle_jet_indices(
{*most_backward, *most_forward}
);
assert(extremal_jet_indices.size() == out_partons.size());
for(size_t i = 0; i < out_partons.size(); ++i){
assert(HEJ::is_parton(out_partons[i]));
const int idx = (extremal_jet_indices[i]>=0)?
extremal_jet_idx:
no_extremal_jet_idx;
out_partons[i].p.set_user_index(idx);
}
return out_partons;
}
double MatrixElement::tree_kin_jets(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> partons,
+ Event const & ev,
bool check_momenta
) const {
- partons = tag_extremal_jet_partons(incoming, partons, check_momenta);
- if(has_unob_gluon(incoming, partons) || has_unof_gluon(incoming, partons)){
+ auto const & incoming = ev.incoming();
+ const auto partons = tag_extremal_jet_partons(ev, check_momenta);
+ if(is_uno(ev.type())){
throw not_implemented("unordered emission not implemented for pure jets");
}
const auto pa = to_HepLorentzVector(incoming[0]);
const auto pb = to_HepLorentzVector(incoming[1]);
const auto p1 = to_HepLorentzVector(partons.front());
const auto pn = to_HepLorentzVector(partons.back());
return ME_current(
incoming[0].type, incoming[1].type,
pn, pb, p1, pa
)/(4*(N_C*N_C - 1))*FKL_ladder_weight(
begin(partons) + 1, end(partons) - 1,
pa - p1, pa, pb, p1, pn
);
}
double MatrixElement::tree_kin_Higgs(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing,
+ Event const & ev,
bool check_momenta
) const {
- if(has_uno_gluon(incoming, outgoing)){
- return tree_kin_Higgs_between(incoming, outgoing, check_momenta);
+ if(is_uno(ev.type())){
+ return tree_kin_Higgs_between(ev, check_momenta);
}
- if(outgoing.front().type == pid::Higgs){
- return tree_kin_Higgs_first(incoming, outgoing, check_momenta);
+ if(ev.outgoing().front().type == pid::Higgs){
+ return tree_kin_Higgs_first(ev, check_momenta);
}
- if(outgoing.back().type == pid::Higgs){
- return tree_kin_Higgs_last(incoming, outgoing, check_momenta);
+ if(ev.outgoing().back().type == pid::Higgs){
+ return tree_kin_Higgs_last(ev, check_momenta);
}
- return tree_kin_Higgs_between(incoming, outgoing, check_momenta);
+ return tree_kin_Higgs_between(ev, check_momenta);
}
namespace {
// Colour acceleration multipliers, for gluons see eq. (7) in arXiv:0910.5113
// TODO: code duplication with currents.cc
double K_g(double p1minus, double paminus) {
return 1./2.*(p1minus/paminus + paminus/p1minus)*(C_A - 1./C_A) + 1./C_A;
}
double K_g(
CLHEP::HepLorentzVector const & pout,
CLHEP::HepLorentzVector const & pin
) {
if(pin.z() > 0) return K_g(pout.plus(), pin.plus());
return K_g(pout.minus(), pin.minus());
}
double K(
ParticleID type,
CLHEP::HepLorentzVector const & pout,
CLHEP::HepLorentzVector const & pin
) {
if(type == ParticleID::gluon) return K_g(pout, pin);
return C_F;
}
// Colour factor in strict MRK limit
double K_MRK(ParticleID type) {
return (type == ParticleID::gluon)?C_A:C_F;
}
}
double MatrixElement::MH2_forwardH(
CLHEP::HepLorentzVector p1out, CLHEP::HepLorentzVector p1in,
ParticleID type2,
CLHEP::HepLorentzVector p2out, CLHEP::HepLorentzVector p2in,
CLHEP::HepLorentzVector pH,
double t1, double t2
) const{
ignore(p2out, p2in);
const double shat = p1in.invariantMass2(p2in);
// gluon case
#ifdef HEJ_BUILD_WITH_QCDLOOP
if(!param_.Higgs_coupling.use_impact_factors){
return K(type2, p2out, p2in)*C_A*1./(16*M_PI*M_PI)*t1/t2*MH2gq_outsideH(
p1out, p1in, p2out, p2in, pH,
param_.Higgs_coupling.mt, param_.Higgs_coupling.include_bottom,
param_.Higgs_coupling.mb
)/(4*(N_C*N_C - 1));
}
#endif
return K_MRK(type2)/C_A*9./2.*shat*shat*(
C2gHgp(p1in,p1out,pH) + C2gHgm(p1in,p1out,pH)
)/(t1*t2);
}
double MatrixElement::tree_kin_Higgs_first(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing,
+ Event const & ev,
bool check_momenta
) const {
+ auto const & incoming = ev.incoming();
+ auto const & outgoing = ev.outgoing();
assert(outgoing.front().type == pid::Higgs);
if(outgoing[1].type != pid::gluon) {
assert(incoming.front().type == outgoing[1].type);
- return tree_kin_Higgs_between(incoming, outgoing, check_momenta);
+ return tree_kin_Higgs_between(ev, check_momenta);
}
const auto pH = to_HepLorentzVector(outgoing.front());
const auto partons = tag_extremal_jet_partons(
- incoming,
- std::vector<Particle>(begin(outgoing) + 1, end(outgoing)),
- check_momenta
+ ev, check_momenta
);
const auto pa = to_HepLorentzVector(incoming[0]);
const auto pb = to_HepLorentzVector(incoming[1]);
const auto p1 = to_HepLorentzVector(partons.front());
const auto pn = to_HepLorentzVector(partons.back());
const auto q0 = pa - p1 - pH;
const double t1 = q0.m2();
const double t2 = (pn - pb).m2();
return MH2_forwardH(
p1, pa, incoming[1].type, pn, pb, pH,
t1, t2
)*FKL_ladder_weight(
begin(partons) + 1, end(partons) - 1,
q0, pa, pb, p1, pn
);
}
double MatrixElement::tree_kin_Higgs_last(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing,
+ Event const & ev,
bool check_momenta
) const {
+ auto const & incoming = ev.incoming();
+ auto const & outgoing = ev.outgoing();
assert(outgoing.back().type == pid::Higgs);
if(outgoing[outgoing.size()-2].type != pid::gluon) {
assert(incoming.back().type == outgoing[outgoing.size()-2].type);
- return tree_kin_Higgs_between(incoming, outgoing, check_momenta);
+ return tree_kin_Higgs_between(ev, check_momenta);
}
const auto pH = to_HepLorentzVector(outgoing.back());
const auto partons = tag_extremal_jet_partons(
- incoming,
- std::vector<Particle>(begin(outgoing), end(outgoing) - 1),
- check_momenta
+ ev, check_momenta
);
const auto pa = to_HepLorentzVector(incoming[0]);
const auto pb = to_HepLorentzVector(incoming[1]);
auto p1 = to_HepLorentzVector(partons.front());
const auto pn = to_HepLorentzVector(partons.back());
auto q0 = pa - p1;
const double t1 = q0.m2();
const double t2 = (pn + pH - pb).m2();
return MH2_forwardH(
pn, pb, incoming[0].type, p1, pa, pH,
t2, t1
)*FKL_ladder_weight(
begin(partons) + 1, end(partons) - 1,
q0, pa, pb, p1, pn
);
}
double MatrixElement::tree_kin_Higgs_between(
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing,
+ Event const & ev,
bool check_momenta
) const {
+ using namespace event_type;
+ auto const & incoming = ev.incoming();
+ auto const & outgoing = ev.outgoing();
+
const auto the_Higgs = std::find_if(
begin(outgoing), end(outgoing),
[](Particle const & s){ return s.type == pid::Higgs; }
);
assert(the_Higgs != end(outgoing));
const auto pH = to_HepLorentzVector(*the_Higgs);
- std::vector<Particle> partons(begin(outgoing), the_Higgs);
- partons.insert(end(partons), the_Higgs + 1, end(outgoing));
- partons = tag_extremal_jet_partons(incoming, partons, check_momenta);
+ const auto partons = tag_extremal_jet_partons(ev, check_momenta);
const auto pa = to_HepLorentzVector(incoming[0]);
const auto pb = to_HepLorentzVector(incoming[1]);
auto p1 = to_HepLorentzVector(
- partons[has_unob_gluon(incoming, outgoing)?1:0]
+ partons[(ev.type() == unob)?1:0]
);
auto pn = to_HepLorentzVector(
- partons[partons.size() - (has_unof_gluon(incoming, outgoing)?2:1)]
+ partons[partons.size() - ((ev.type() == unof)?2:1)]
);
auto first_after_Higgs = begin(partons) + (the_Higgs-begin(outgoing));
assert(
(first_after_Higgs == end(partons) && (
- has_unob_gluon(incoming, outgoing)
+ (ev.type() == unob)
|| partons.back().type != pid::gluon
))
|| first_after_Higgs->rapidity() >= the_Higgs->rapidity()
);
assert(
(first_after_Higgs == begin(partons) && (
- has_unof_gluon(incoming, outgoing)
+ (ev.type() == unof)
|| partons.front().type != pid::gluon
))
|| (first_after_Higgs-1)->rapidity() <= the_Higgs->rapidity()
);
// always treat the Higgs as if it were in between the extremal FKL partons
if(first_after_Higgs == begin(partons)) ++first_after_Higgs;
else if(first_after_Higgs == end(partons)) --first_after_Higgs;
// t-channel momentum before Higgs
auto qH = pa;
for(auto parton_it = begin(partons); parton_it != first_after_Higgs; ++parton_it){
qH -= to_HepLorentzVector(*parton_it);
}
auto q0 = pa - p1;
auto begin_ladder = begin(partons) + 1;
auto end_ladder = end(partons) - 1;
double current_factor;
- if(has_unob_gluon(incoming, outgoing)){
+ if(ev.type() == unob){
current_factor = C_A*C_A/2.*ME_Higgs_current_unob( // 1/2 = "K_uno"
incoming[0].type, incoming[1].type,
pn, pb, to_HepLorentzVector(partons.front()), p1, pa, qH, qH - pH,
param_.Higgs_coupling.mt,
param_.Higgs_coupling.include_bottom, param_.Higgs_coupling.mb
);
const auto p_unob = to_HepLorentzVector(partons.front());
q0 -= p_unob;
p1 += p_unob;
++begin_ladder;
}
- else if(has_unof_gluon(incoming, outgoing)){
+ else if(ev.type() == unof){
current_factor = C_A*C_A/2.*ME_Higgs_current_unof( // 1/2 = "K_uno"
incoming[0].type, incoming[1].type,
to_HepLorentzVector(partons.back()), pn, pb, p1, pa, qH, qH - pH,
param_.Higgs_coupling.mt,
param_.Higgs_coupling.include_bottom, param_.Higgs_coupling.mb
);
pn += to_HepLorentzVector(partons.back());
--end_ladder;
}
else{
current_factor = ME_Higgs_current(
incoming[0].type, incoming[1].type,
pn, pb, p1, pa, qH, qH - pH,
param_.Higgs_coupling.mt,
param_.Higgs_coupling.include_bottom, param_.Higgs_coupling.mb
);
}
const double ladder_factor = FKL_ladder_weight(
begin_ladder, first_after_Higgs,
q0, pa, pb, p1, pn
)*FKL_ladder_weight(
first_after_Higgs, end_ladder,
qH - pH, pa, pb, p1, pn
);
return current_factor*C_A*C_A/(N_C*N_C-1.)*ladder_factor;
}
double MatrixElement::tree_param_partons(
double alpha_s, double mur,
std::vector<Particle> const & partons
) const{
const double gs2 = 4.*M_PI*alpha_s;
double wt = std::pow(gs2, partons.size());
if(param_.log_correction){
// use alpha_s(q_perp), evolved to mur
assert(partons.size() >= 2);
for(size_t i = 1; i < partons.size()-1; ++i){
wt *= 1 + alpha_s/(2*M_PI)*beta0*log(mur/partons[i].p.perp());
}
}
return wt;
}
double MatrixElement::tree_param(
- double mur,
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing
+ Event const & ev,
+ double mur
) const{
+ assert(is_HEJ(ev.type()));
+
+ const auto & out = ev.outgoing();
const double alpha_s = alpha_s_(mur);
auto AWZH_boson = std::find_if(
- begin(outgoing), end(outgoing),
+ begin(out), end(out),
[](auto const & p){return is_AWZH_boson(p);}
);
double AWZH_coupling = 1.;
- if(AWZH_boson != end(outgoing)){
+ if(AWZH_boson != end(out)){
switch(AWZH_boson->type){
case pid::Higgs: {
AWZH_coupling = alpha_s*alpha_s;
break;
}
// TODO
case pid::Wp:
case pid::Wm:
case pid::photon:
case pid::Z:
default:
- throw std::logic_error("Emission of boson of unsupported type");
+ throw not_implemented("Emission of boson of unsupported type");
}
}
- if(has_unob_gluon(incoming, outgoing)){
+ if(ev.type() == event_type::unob){
return AWZH_coupling*4*M_PI*alpha_s*tree_param_partons(
- alpha_s, mur, filter_partons({begin(outgoing) + 1, end(outgoing)})
+ alpha_s, mur, filter_partons({begin(out) + 1, end(out)})
);
}
- if(has_unof_gluon(incoming, outgoing)){
+ if(ev.type() == event_type::unof){
return AWZH_coupling*4*M_PI*alpha_s*tree_param_partons(
- alpha_s, mur, filter_partons({begin(outgoing), end(outgoing) - 1})
+ alpha_s, mur, filter_partons({begin(out), end(out) - 1})
);
}
- return AWZH_coupling*tree_param_partons(alpha_s, mur, filter_partons(outgoing));
+ return AWZH_coupling*tree_param_partons(alpha_s, mur, filter_partons(out));
}
- double MatrixElement::tree(
- double mur,
- std::array<Particle, 2> const & incoming,
- std::vector<Particle> const & outgoing,
- bool check_momenta
- ) const {
- return tree_param(mur, incoming, outgoing)*tree_kin(
- incoming, outgoing, check_momenta
- );
- }
} // namespace HEJ
diff --git a/src/PhaseSpacePoint.cc b/src/PhaseSpacePoint.cc
index d3f1850..ff32eb3 100644
--- a/src/PhaseSpacePoint.cc
+++ b/src/PhaseSpacePoint.cc
@@ -1,538 +1,537 @@
#include "HEJ/PhaseSpacePoint.hh"
#include <random>
#include <CLHEP/Random/Randomize.h>
#include <CLHEP/Random/RanluxEngine.h>
#include "HEJ/Constants.hh"
#include "HEJ/resummation_jet.hh"
-#include "HEJ/uno.hh"
#include "HEJ/utility.hh"
#include "HEJ/kinematics.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 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{}));
}
PhaseSpacePoint::PhaseSpacePoint(
Event const & ev, PhaseSpacePointConfig conf, HEJ::RNG & ran
):
- unob_{has_unob_gluon(ev.incoming(), ev.outgoing())},
- unof_{!unob_ && has_unof_gluon(ev.incoming(), ev.outgoing())},
+ unob_{ev.type() == event_type::unob},
+ unof_{ev.type() == event_type::unof},
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)});
}
most_backward_FKL(outgoing_).type = ev.incoming().front().type;
most_forward_FKL(outgoing_).type = ev.incoming().back().type;
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_ && jets[0].delta_R(jets[1]) > R_eff){
++first_valid_jet;
--num_valid_jets;
}
else if(unof_ && 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_;
const size_t most_forward_FKL_idx = jets.size() - 1 - unof_;
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((unob_ && i == 0) || i == most_backward_FKL_idx){
// unordered or FKL backward emission
extremal = std::min_element(
first_new_parton, end(jet_partons), rapidity_less{}
);
extremal->set_user_index(
(i == most_backward_FKL_idx)?backward_FKL_idx:unob_idx
);
}
else if((unof_ && i == jets.size() - 1) || i == most_forward_FKL_idx){
// unordered or FKL forward emission
extremal = std::max_element(
first_new_parton, end(jet_partons), rapidity_less{}
);
extremal->set_user_index(
(i == most_forward_FKL_idx)?forward_FKL_idx:unof_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;
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_];
}
template<class Particle>
Particle const & PhaseSpacePoint::most_forward_FKL(
std::vector<Particle> const & partons
) const{
const size_t idx = partons.size() - 1 - unof_;
assert(idx < partons.size());
return partons[idx];
}
template<class Particle>
Particle & PhaseSpacePoint::most_backward_FKL(
std::vector<Particle> & partons
) const{
return partons[0 + unob_];
}
template<class Particle>
Particle & PhaseSpacePoint::most_forward_FKL(
std::vector<Particle> & partons
) const{
const size_t idx = partons.size() - 1 - unof_;
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
diff --git a/src/Weights.cc b/src/Weights.cc
new file mode 100644
index 0000000..9e0ee9c
--- /dev/null
+++ b/src/Weights.cc
@@ -0,0 +1,41 @@
+#include "HEJ/Weights.hh"
+
+#include <stdexcept>
+
+namespace HEJ {
+
+ Weights& Weights::operator*=(Weights const & other) {
+ if(other.variations.size() != variations.size()) {
+ throw std::invalid_argument{"Wrong number of weights"};
+ }
+ central *= other.central;
+ for(std::size_t i = 0; i < variations.size(); ++i) {
+ variations[i] *= other.variations[i];
+ }
+ return *this;
+ }
+
+ Weights& Weights::operator*=(double factor) {
+ central *= factor;
+ for(auto & wt: variations) wt *= factor;
+ return *this;
+ }
+
+ Weights& Weights::operator/=(Weights const & other) {
+ if(other.variations.size() != variations.size()) {
+ throw std::invalid_argument{"Wrong number of weights"};
+ }
+ central /= other.central;
+ for(std::size_t i = 0; i < variations.size(); ++i) {
+ variations[i] /= other.variations[i];
+ }
+ return *this;
+ }
+
+ Weights& Weights::operator/=(double factor) {
+ central /= factor;
+ for(auto & wt: variations) wt /= factor;
+ return *this;
+ }
+
+}
diff --git a/t/check_res.cc b/t/check_res.cc
index 50b4325..9ef2ffd 100644
--- a/t/check_res.cc
+++ b/t/check_res.cc
@@ -1,97 +1,96 @@
#include <iostream>
#include "LHEF/LHEF.h"
#include "HEJ/stream.hh"
#include "HEJ/EventReweighter.hh"
#include "HEJ/Mixmax.hh"
namespace{
const fastjet::JetDefinition jet_def{fastjet::kt_algorithm, 0.4};
const fastjet::JetDefinition Born_jet_def{jet_def};
constexpr double Born_jetptmin = 30;
constexpr double extpartonptmin = 30;
constexpr double max_ext_soft_pt_fraction =
std::numeric_limits<double>::infinity();
constexpr double jetptmin = 35;
constexpr bool log_corr = false;
using EventTreatment = HEJ::EventTreatment;
using namespace HEJ::event_type;
HEJ::EventTreatMap treat{
{no_2_jets, EventTreatment::discard},
{bad_final_state, EventTreatment::discard},
{nonHEJ, EventTreatment::discard},
{unof, EventTreatment::discard},
{unob, EventTreatment::discard},
{FKL, EventTreatment::reweight}
};
};
int main(int argn, char** argv) {
if(argn == 5 && std::string(argv[4]) == "uno"){
--argn;
treat[unof] = EventTreatment::reweight;
treat[unob] = EventTreatment::reweight;
treat[FKL] = EventTreatment::discard;
}
if(argn != 4){
std::cerr << "Usage: check_res eventfile xsection tolerance [uno]";
return EXIT_FAILURE;
}
const double xsec_ref = std::stod(argv[2]);
const double tolerance = std::stod(argv[3]);
HEJ::istream in{argv[1]};
LHEF::Reader reader{in};
HEJ::PhaseSpacePointConfig psp_conf;
psp_conf.jet_param = HEJ::JetParameters{jet_def, jetptmin};
psp_conf.min_extparton_pt = extpartonptmin;
psp_conf.max_ext_soft_pt_fraction = max_ext_soft_pt_fraction;
HEJ::MatrixElementConfig ME_conf;
- ME_conf.jet_param = psp_conf.jet_param;
ME_conf.log_correction = log_corr;
ME_conf.Higgs_coupling = HEJ::HiggsCouplingSettings{};
HEJ::EventReweighterConfig conf;
conf.psp_config = std::move(psp_conf);
conf.ME_config = std::move(ME_conf);
conf.jet_param = psp_conf.jet_param;
conf.treat = treat;
reader.readEvent();
const bool has_Higgs = std::find(
begin(reader.hepeup.IDUP),
end(reader.hepeup.IDUP),
25
) != end(reader.hepeup.IDUP);
const double mu = has_Higgs?125.:91.188;
HEJ::ScaleGenerator scale_gen{
{{std::to_string(mu), HEJ::FixedScale{mu}}}, {}, 1.
};
HEJ::Mixmax ran{};
HEJ::EventReweighter hej{reader.heprup, std::move(scale_gen), conf, ran};
double xsec = 0.;
double xsec_err = 0.;
do{
HEJ::Event ev{
HEJ::UnclusteredEvent{reader.hepeup},
Born_jet_def, Born_jetptmin
};
auto resummed_events = hej.reweight(ev, 20);
for(auto const & ev: resummed_events) {
xsec += ev.central().weight;
xsec_err += ev.central().weight*ev.central().weight;
}
} while(reader.readEvent());
xsec_err = std::sqrt(xsec_err);
const double significance =
std::abs(xsec - xsec_ref) / std::sqrt( xsec_err*xsec_err + tolerance*tolerance );
std::cout << xsec_ref << " +/- " << tolerance << " ~ "
<< xsec << " +- " << xsec_err << " => " << significance << " sigma\n";
if(significance > 3.){
std::cerr << "Cross section is off by over 3 sigma!\n";
return EXIT_FAILURE;
}
}
diff --git a/t/test_ME_generic.cc b/t/test_ME_generic.cc
index 8563223..33a9077 100644
--- a/t/test_ME_generic.cc
+++ b/t/test_ME_generic.cc
@@ -1,104 +1,104 @@
// Generic tester for the ME for a given set of PSP
// reference weights and PSP (as LHE file) have to be given as _individual_ files
#include <fstream>
#include "LHEF/LHEF.h"
#include "HEJ/MatrixElement.hh"
#include "HEJ/Event.hh"
#include "HEJ/YAMLreader.hh"
#include "HEJ/stream.hh"
constexpr double alpha_s = 0.118;
-constexpr double mu = 1234.; // coupling fixed, mu doesn't matter
constexpr double ep = 1e-6;
-void dump(HEJ::UnclusteredEvent const & ev, HEJ::Config config){
+void dump(HEJ::Event const & ev){
{
LHEF::Writer writer{std::cout};
std::cout << std::setprecision(6);
- HEJ::Event out_ev{ev, config.resummation_jets.def, config.resummation_jets.min_pt};
- writer.hepeup = to_HEPEUP(std::move(out_ev), nullptr);
+ writer.hepeup = to_HEPEUP(std::move(ev), nullptr);
writer.writeEvent();
}
std::cout << "Rapidity ordering:\n";
- for(const auto & part: ev.outgoing){
+ for(const auto & part: ev.outgoing()){
std::cout << std::setw(2) << part.type << ": "<< std::setw(7) << part.rapidity() << std::endl;
}
}
int main(int argn, char** argv){
if(argn != 4 && argn != 5){
std::cerr << "\n# Usage:\n."<< argv[0] <<" config.yml ME_weights input_file.lhe\n\n";
return EXIT_FAILURE;
}
bool OUTPUT_MODE = false;
if(argn == 5 && std::string("OUTPUT")==std::string(argv[4]))
OUTPUT_MODE = true;
const HEJ::Config config = HEJ::load_config(argv[1]);
std::fstream wgt_file;
if ( OUTPUT_MODE ) {
std::cout << "_______________________USING OUTPUT MODE!_______________________" << std::endl;
wgt_file.open(argv[2], std::fstream::out);
wgt_file.precision(10);
} else {
wgt_file.open(argv[2], std::fstream::in);
}
HEJ::istream in{argv[3]};
LHEF::Reader reader{in};
HEJ::MatrixElement ME{
[](double){ return alpha_s; },
HEJ::to_MatrixElementConfig(config)
};
double max_ratio = 0.;
size_t idx_max_ratio = 0;
- HEJ::UnclusteredEvent ev_max_ratio;
+ HEJ::Event ev_max_ratio;
double av_ratio = 0;
size_t i = 0;
while(reader.readEvent()){
++i;
- HEJ::UnclusteredEvent event{reader.hepeup};
- const double our_ME = ME.tree(
- mu, event.incoming, event.outgoing, true
- );
+ HEJ::Event event{
+ HEJ::UnclusteredEvent{reader.hepeup},
+ config.resummation_jets.def,
+ config.resummation_jets.min_pt
+ };
+ const double our_ME = ME.tree(event, true).central;
if ( OUTPUT_MODE ) {
wgt_file << our_ME << std::endl;
} else {
std::string line;
if(!std::getline(wgt_file,line)) break;
const double ref_ME = std::stod(line);
const double diff = std::abs(our_ME/ref_ME-1.);
av_ratio+=diff;
if( diff > max_ratio ) {
max_ratio = diff;
idx_max_ratio = i;
ev_max_ratio = event;
}
if( diff > ep ){
size_t precision(std::cout.precision());
std::cout.precision(16);
std::cout<< "Large difference in PSP " << i << "\nis: "<<our_ME << " should: " << ref_ME << " => difference: " << diff << std::endl;
std::cout.precision(precision);
- dump(event, config);
+ dump(event);
return EXIT_FAILURE;
}
}
}
wgt_file.close();
if ( !OUTPUT_MODE ) {
size_t precision(std::cout.precision());
std::cout.precision(16);
std::cout << "Avg ratio after " << i << " PSP: " << av_ratio/i << std::endl;
std::cout << "maximal ratio at " << idx_max_ratio << ": " << max_ratio << std::endl;
std::cout.precision(precision);
}
return EXIT_SUCCESS;
}