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| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/LeadingParticlesFinalState.hh"
#include "Rivet/Projections/VetoedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
namespace Rivet {
/// @brief Measurement of isolated gamma + jet + X differential cross-sections
///
/// Inclusive isolated gamma + jet cross-sections, differential in pT(gamma), for
/// various photon and jet rapidity configurations.
///
/// @author Giovanni Marchiori
class ATLAS_2012_I1093738 : public Analysis {
public:
// Constructor
ATLAS_2012_I1093738()
: Analysis("ATLAS_2012_I1093738")
{ }
// Book histograms and initialise projections before the run
void init() {
// Final state
FinalState fs;
declare(fs, "FS");
// Voronoi eta-phi tessellation with KT jets, for ambient energy density calculation
FastJets fj(fs, FastJets::KT, 0.5);
fj.useJetArea(new fastjet::AreaDefinition(fastjet::VoronoiAreaSpec()));
declare(fj, "KtJetsD05");
// Leading photon
LeadingParticlesFinalState photonfs(FinalState((Cuts::etaIn(-1.37, 1.37) && Cuts::pT >= 25.0*GeV)));
photonfs.addParticleId(PID::PHOTON);
declare(photonfs, "LeadingPhoton");
// FS excluding the leading photon
VetoedFinalState vfs(fs);
vfs.addVetoOnThisFinalState(photonfs);
declare(vfs, "JetFS");
// Jets
FastJets jetpro(vfs, FastJets::ANTIKT, 0.4);
jetpro.useInvisibles();
declare(jetpro, "Jets");
book(_h_phbarrel_jetcentral_SS ,1, 1, 1);
book(_h_phbarrel_jetmedium_SS ,2, 1, 1);
book(_h_phbarrel_jetforward_SS ,3, 1, 1);
book(_h_phbarrel_jetcentral_OS ,4, 1, 1);
book(_h_phbarrel_jetmedium_OS ,5, 1, 1);
book(_h_phbarrel_jetforward_OS ,6, 1, 1);
}
int getEtaBin(double eta, int what) const {
const double aeta = fabs(eta);
if (what == 0) return binIndex(aeta, _eta_bins_ph);
if (what == 1) return binIndex(aeta, _eta_bins_jet);
return binIndex(aeta, _eta_bins_areaoffset);
}
// Perform the per-event analysis
void analyze(const Event& event) {
// Get the photon
const FinalState& photonfs = apply<FinalState>(event, "LeadingPhoton");
if (photonfs.particles().size() < 1) vetoEvent;
const FourMomentum photon = photonfs.particles().front().momentum();
// Get the jet
Jets jets = apply<FastJets>(event, "Jets").jetsByPt(20.0*GeV);
if (jets.empty()) vetoEvent;
FourMomentum leadingJet = jets[0].momentum();
// Require jet separated from photon
if (deltaR(photon, leadingJet) < 1.0) vetoEvent;
// Veto if leading jet is outside plotted rapidity regions
if (leadingJet.absrap() > 4.4) vetoEvent;
// Compute the jet pT densities
vector< vector<double> > ptDensities(_eta_bins_areaoffset.size()-1);
FastJets fastjets = apply<FastJets>(event, "KtJetsD05");
const shared_ptr<fastjet::ClusterSequenceArea> clust_seq_area = fastjets.clusterSeqArea();
for (const Jet& jet : fastjets.jets()) {
const double area = clust_seq_area->area(jet); //< Implicit call to pseudojet()
if (area > 1e-4 && jet.abseta() < _eta_bins_areaoffset.back()) {
ptDensities.at(getEtaBin(jet.abseta(), 2)) += jet.pT()/area;
}
}
// Compute the median event energy density
/// @todo This looks equivalent to median(ptDensities[b]) -- isn't SKIPNHARDJETS meant to be used as an offset?
const unsigned int SKIPNHARDJETS = 0;
vector<double> ptDensity;
for (size_t b = 0; b < _eta_bins_areaoffset.size()-1; b++) {
double median = 0.0;
if (ptDensities[b].size() > SKIPNHARDJETS) {
std::sort(ptDensities[b].begin(), ptDensities[b].end());
const int nDens = ptDensities[b].size() - SKIPNHARDJETS;
if (nDens % 2 == 0) {
median = (ptDensities[b][nDens/2]+ptDensities[b][(nDens-2)/2])/2;
} else {
median = ptDensities[b][(nDens-1)/2];
}
}
ptDensity.push_back(median);
}
// Compute photon isolation with a standard ET cone
const Particles fs = apply<FinalState>(event, "JetFS").particles();
FourMomentum mom_in_EtCone;
const double ISO_DR = 0.4;
const double CLUSTER_ETA_WIDTH = 0.25*5.0;
const double CLUSTER_PHI_WIDTH = (PI/128.)*7.0;
for (const Particle& p : fs) {
// Check if it's in the cone of .4
if (deltaR(photon, p) >= ISO_DR) continue;
// Check if it's in the 5x7 central core
if (fabs(deltaEta(photon, p)) < CLUSTER_ETA_WIDTH*0.5 &&
fabs(deltaPhi(photon, p)) < CLUSTER_PHI_WIDTH*0.5) continue;
// Increment sum
mom_in_EtCone += p.momentum();
}
// Figure out the correction (area*density)
const double ETCONE_AREA = PI*ISO_DR*ISO_DR - CLUSTER_ETA_WIDTH*CLUSTER_PHI_WIDTH;
const double correction = ptDensity[getEtaBin(photon.abseta(),2)] * ETCONE_AREA;
// Require photon to be isolated
if (mom_in_EtCone.Et()-correction > 4.0*GeV) vetoEvent;
const int photon_jet_sign = sign( leadingJet.rapidity() * photon.rapidity() );
// Fill histos
const double abs_jet_rapidity = fabs(leadingJet.rapidity());
const double photon_pt = photon.pT()/GeV;
const double abs_photon_eta = fabs(photon.eta());
if (abs_photon_eta < 1.37) {
if (abs_jet_rapidity < 1.2) {
if (photon_jet_sign >= 1) {
_h_phbarrel_jetcentral_SS->fill(photon_pt);
} else {
_h_phbarrel_jetcentral_OS->fill(photon_pt);
}
} else if (abs_jet_rapidity < 2.8) {
if (photon_jet_sign >= 1) {
_h_phbarrel_jetmedium_SS->fill(photon_pt);
} else {
_h_phbarrel_jetmedium_OS->fill(photon_pt);
}
} else if (abs_jet_rapidity < 4.4) {
if (photon_jet_sign >= 1) {
_h_phbarrel_jetforward_SS->fill(photon_pt);
} else {
_h_phbarrel_jetforward_OS->fill(photon_pt);
}
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
scale(_h_phbarrel_jetcentral_SS, crossSection()/sumOfWeights());
scale(_h_phbarrel_jetcentral_OS, crossSection()/sumOfWeights());
scale(_h_phbarrel_jetmedium_SS, crossSection()/sumOfWeights());
scale(_h_phbarrel_jetmedium_OS, crossSection()/sumOfWeights());
scale(_h_phbarrel_jetforward_SS, crossSection()/sumOfWeights());
scale(_h_phbarrel_jetforward_OS, crossSection()/sumOfWeights());
}
private:
Histo1DPtr _h_phbarrel_jetcentral_SS, _h_phbarrel_jetmedium_SS, _h_phbarrel_jetforward_SS;
Histo1DPtr _h_phbarrel_jetcentral_OS, _h_phbarrel_jetmedium_OS, _h_phbarrel_jetforward_OS;
const vector<double> _eta_bins_ph = {0.0, 1.37, 1.52, 2.37};
const vector<double> _eta_bins_jet = {0.0, 1.2, 2.8, 4.4};
const vector<double> _eta_bins_areaoffset = {0.0, 1.5, 3.0};
};
// The hook for the plugin system
RIVET_DECLARE_PLUGIN(ATLAS_2012_I1093738);
}
|