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D0_2008_S7719523.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Tools/Logging.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/LeadingParticlesFinalState.hh"
#include "Rivet/Projections/VetoedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/RivetAIDA.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 bins.
///
/// @author Andy Buckley
/// @author Gavin Hesketh
class D0_2008_S7719523 : public Analysis {
public:
/// @name Constructors etc.
//@{
/// Constructor
D0_2008_S7719523()
: Analysis("D0_2008_S7719523")
{ }
//@}
/// @name Analysis methods
//@{
/// Set up projections and book histograms
void init() {
// General FS
FinalState fs;
addProjection(fs, "FS");
// Get leading photon
LeadingParticlesFinalState photonfs(FinalState(-1.0, 1.0, 30.0*GeV));
photonfs.addParticleId(PHOTON);
addProjection(photonfs, "LeadingPhoton");
// FS excluding the leading photon
VetoedFinalState vfs(fs);
vfs.addVetoOnThisFinalState(photonfs);
addProjection(vfs, "JetFS");
// Jets
FastJets jetpro(vfs, FastJets::D0ILCONE, 0.7);
addProjection(jetpro, "Jets");
// Histograms
_h_central_same_cross_section = bookHistogram1D(1, 1, 1);
_h_central_opp_cross_section = bookHistogram1D(2, 1, 1);
_h_forward_same_cross_section = bookHistogram1D(3, 1, 1);
_h_forward_opp_cross_section = bookHistogram1D(4, 1, 1);
}
/// Do the analysis
void analyze(const Event& event) {
const double weight = event.weight();
// Get the photon
const FinalState& photonfs = applyProjection<FinalState>(event, "LeadingPhoton");
if (photonfs.particles().size() != 1) {
vetoEvent;
}
const FourMomentum photon = photonfs.particles().front().momentum();
// Isolate photon by ensuring that a 0.4 cone around it contains less than 7% of the photon's energy
double egamma = photon.E();
double eta_P = photon.pseudorapidity();
double phi_P = photon.azimuthalAngle();
double econe = 0.0;
foreach (const Particle& p, applyProjection<FinalState>(event, "JetFS").particles()) {
if (deltaR(eta_P, phi_P,
p.momentum().pseudorapidity(), p.momentum().azimuthalAngle()) < 0.4) {
econe += p.momentum().E();
// Veto as soon as E_cone gets larger
if (econe/egamma > 0.07) {
MSG_DEBUG("Vetoing event because photon is insufficiently isolated");
vetoEvent;
}
}
}
Jets jets = applyProjection<FastJets>(event, "Jets").jetsByPt(15.0*GeV);
if (jets.size()==0) {
vetoEvent;
}
FourMomentum leadingJet = jets[0].momentum();
if (deltaR(eta_P, phi_P, leadingJet.eta(), leadingJet.phi())<0.7) {
vetoEvent;
}
int photon_jet_sign = sign( leadingJet.rapidity() * photon.rapidity() );
// Veto if leading jet is outside plotted rapidity regions
const double abs_y1 = fabs(leadingJet.rapidity());
if (inRange(abs_y1, 0.8, 1.5) || abs_y1 > 2.5) {
MSG_DEBUG("Leading jet falls outside acceptance range; |y1| = "
<< abs_y1);
vetoEvent;
}
// Fill histos
if (fabs(leadingJet.rapidity()) < 0.8) {
if (photon_jet_sign >= 1) {
_h_central_same_cross_section->fill(photon.pT(), weight);
} else {
_h_central_opp_cross_section->fill(photon.pT(), weight);
}
} else if (inRange( fabs(leadingJet.rapidity()), 1.5, 2.5)) {
if (photon_jet_sign >= 1) {
_h_forward_same_cross_section->fill(photon.pT(), weight);
} else {
_h_forward_opp_cross_section->fill(photon.pT(), weight);
}
}
}
/// Finalize
void finalize() {
const double lumi_gen = sumOfWeights()/crossSection();
const double dy_photon = 2.0;
const double dy_jet_central = 1.6;
const double dy_jet_forward = 2.0;
// Cross-section ratios (6 plots)
// Central/central and forward/forward ratios
AIDA::IHistogramFactory& hf = histogramFactory();
const string dir = histoDir();
hf.divide(dir + "/d05-x01-y01", *_h_central_opp_cross_section, *_h_central_same_cross_section);
hf.divide(dir + "/d08-x01-y01", *_h_forward_opp_cross_section, *_h_forward_same_cross_section);
// Central/forward ratio combinations
hf.divide(dir + "/d06-x01-y01", *_h_central_same_cross_section,
*_h_forward_same_cross_section)->scale(dy_jet_forward/dy_jet_central, 1);
hf.divide(dir + "/d07-x01-y01", *_h_central_opp_cross_section,
*_h_forward_same_cross_section)->scale(dy_jet_forward/dy_jet_central, 1);
hf.divide(dir + "/d09-x01-y01", *_h_central_same_cross_section,
*_h_forward_opp_cross_section)->scale(dy_jet_forward/dy_jet_central, 1);
hf.divide(dir + "/d10-x01-y01", *_h_central_opp_cross_section,
*_h_forward_opp_cross_section)->scale(dy_jet_forward/dy_jet_central, 1);
// Use generator cross section for remaining histograms
// Each of these needs the additional factor 2 because the
// y_photon * y_jet requirement reduces the corresponding 2D "bin width"
// by a factor 1/2.
scale(_h_central_same_cross_section, 2.0/lumi_gen * 1.0/dy_photon * 1.0/dy_jet_central);
scale(_h_central_opp_cross_section, 2.0/lumi_gen * 1.0/dy_photon * 1.0/dy_jet_central);
scale(_h_forward_same_cross_section, 2.0/lumi_gen * 1.0/dy_photon * 1.0/dy_jet_forward);
scale(_h_forward_opp_cross_section, 2.0/lumi_gen * 1.0/dy_photon * 1.0/dy_jet_forward);
}
//@}
private:
/// @name Histograms
//@{
AIDA::IHistogram1D* _h_central_same_cross_section;
AIDA::IHistogram1D* _h_central_opp_cross_section;
AIDA::IHistogram1D* _h_forward_same_cross_section;
AIDA::IHistogram1D* _h_forward_opp_cross_section;
//@}
};
// The hook for the plugin system
DECLARE_RIVET_PLUGIN(D0_2008_S7719523);
}

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