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Rivet analyses reference

MC_PHOTONJETS

Monte Carlo validation observables for photon + jets production
Experiment: ()
Status: VALIDATED
Authors:
  • Frank Siegert
No references listed
Beams: * *
Beam energies: ANY
Run details:
  • Tevatron Run II ppbar -> gamma + jets.

Different observables related to the photon and extra jets.

Source code: MC_PHOTONJETS.cc
  1// -*- C++ -*-
  2#include "Rivet/Analyses/MC_JetAnalysis.hh"
  3#include "Rivet/Projections/LeadingParticlesFinalState.hh"
  4#include "Rivet/Projections/VetoedFinalState.hh"
  5#include "Rivet/Projections/FastJets.hh"
  6
  7namespace Rivet {
  8
  9  
 10
 11
 12  /// @brief MC validation analysis for photon + jets events
 13  class MC_PHOTONJETS : public MC_JetAnalysis {
 14  public:
 15
 16    /// Default constructor
 17    MC_PHOTONJETS()
 18      : MC_JetAnalysis("MC_PHOTONJETS", 4, "Jets")
 19    {    }
 20
 21
 22    /// @name Analysis methods
 23    //@{
 24
 25    /// Book histograms
 26    void init() {
 27      // General FS
 28      FinalState fs((Cuts::etaIn(-5.0, 5.0)));
 29      declare(fs, "FS");
 30
 31      // Get leading photon
 32      LeadingParticlesFinalState photonfs(FinalState(Cuts::abseta < 2.5 && Cuts::pT >= 30*GeV));
 33      photonfs.addParticleId(PID::PHOTON);
 34      declare(photonfs, "LeadingPhoton");
 35
 36      // FS for jets excludes the leading photon
 37      VetoedFinalState vfs(fs);
 38      vfs.addVetoOnThisFinalState(photonfs);
 39      declare(vfs, "JetFS");
 40      FastJets jetpro(vfs, FastJets::ANTIKT, 0.4);
 41      declare(jetpro, "Jets");
 42
 43      book(_h_photon_jet1_deta ,"photon_jet1_deta", 50, -5.0, 5.0);
 44      book(_h_photon_jet1_dphi ,"photon_jet1_dphi", 20, 0.0, M_PI);
 45      book(_h_photon_jet1_dR ,"photon_jet1_dR", 25, 0.5, 7.0);
 46
 47      MC_JetAnalysis::init();
 48    }
 49
 50
 51    /// Do the analysis
 52    void analyze(const Event& e) {
 53      // Get the photon
 54      /// @todo share IsolatedPhoton projection between all MC_*PHOTON* analyses
 55      const Particles photons = apply<FinalState>(e, "LeadingPhoton").particles();
 56      if (photons.size() != 1) {
 57        vetoEvent;
 58      }
 59      const FourMomentum photon = photons.front().momentum();
 60
 61      // Get all charged particles
 62      const FinalState& fs = apply<FinalState>(e, "JetFS");
 63      if (fs.empty()) {
 64        vetoEvent;
 65      }
 66
 67      // Passed cuts, so get the weight
 68      const double weight = 1.0;
 69
 70      // Isolate photon by ensuring that a 0.4 cone around it contains less than 7% of the photon's energy
 71      const double egamma = photon.E();
 72      double econe = 0.0;
 73      for (const Particle& p : fs.particles()) {
 74        if (deltaR(photon, p.momentum()) < 0.4) {
 75          econe += p.E();
 76          // Veto as soon as E_cone gets larger
 77          if (econe/egamma > 0.07) {
 78            vetoEvent;
 79          }
 80        }
 81      }
 82
 83      const Jets& jets = apply<FastJets>(e, "Jets").jetsByPt(_jetptcut);
 84      if (jets.size()>0) {
 85        _h_photon_jet1_deta->fill(photon.eta()-jets[0].eta(), weight);
 86        _h_photon_jet1_dphi->fill(mapAngle0ToPi(photon.phi()-jets[0].phi()), weight);
 87        _h_photon_jet1_dR->fill(deltaR(photon, jets[0].momentum()), weight);
 88      }
 89
 90      MC_JetAnalysis::analyze(e);
 91    }
 92
 93
 94    // Finalize
 95    void finalize() {
 96      scale(_h_photon_jet1_deta, crossSectionPerEvent());
 97      scale(_h_photon_jet1_dphi, crossSectionPerEvent());
 98      scale(_h_photon_jet1_dR, crossSectionPerEvent());
 99
100      MC_JetAnalysis::finalize();
101    }
102
103    //@}
104
105
106  private:
107
108    /// @name Histograms
109    //@{
110    Histo1DPtr _h_photon_jet1_deta;
111    Histo1DPtr _h_photon_jet1_dphi;
112    Histo1DPtr _h_photon_jet1_dR;
113    //@}
114
115  };
116
117
118
119  // The hook for the plugin system
120  RIVET_DECLARE_PLUGIN(MC_PHOTONJETS);
121
122}