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Rivet analyses reference

MC_DIPHOTON

Monte Carlo validation observables for diphoton production at LHC
Experiment: ()
Status: VALIDATED
Authors:
  • Frank Siegert
No references listed
Beams: * *
Beam energies: ANY
Run details:
  • LHC pp -> jet+jet, photon+jet, photon+photon, all with EW+QCD shower

Different observables related to the two photons

Source code: MC_DIPHOTON.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/FinalState.hh"
  4#include "Rivet/Projections/IdentifiedFinalState.hh"
  5
  6namespace Rivet {
  7
  8  
  9
 10
 11  /// @brief MC validation analysis for isolated di-photon events
 12  class MC_DIPHOTON : public Analysis {
 13  public:
 14
 15    /// Constructor
 16    MC_DIPHOTON()
 17      : Analysis("MC_DIPHOTON")
 18    {    }
 19
 20
 21    /// @name Analysis methods
 22    //@{
 23
 24    void init() {
 25      FinalState fs;
 26      declare(fs, "FS");
 27
 28      IdentifiedFinalState ifs(Cuts::abseta < 2 && Cuts::pT > 20*GeV);
 29      ifs.acceptId(PID::PHOTON);
 30      declare(ifs, "IFS");
 31
 32      book(_h_m_PP ,"m_PP", logspace(50, 1.0, 0.25*(sqrtS()>0.?sqrtS():14000.)));
 33      book(_h_pT_PP ,"pT_PP", logspace(50, 1.0, 0.25*(sqrtS()>0.?sqrtS():14000.)));
 34      book(_h_pT_P1 ,"pT_P1", 50, 0.0, 70.0);
 35      book(_h_pT_P2 ,"pT_P2", 50, 0.0, 70.0);
 36      book(_h_dphi_PP ,"dphi_PP", 20, 0.0, M_PI);
 37    }
 38
 39
 40    void analyze(const Event& event) {
 41      const double weight = 1.0;
 42
 43      const Particles& photons = apply<IdentifiedFinalState>(event, "IFS").particlesByPt();
 44
 45      if (photons.size() < 2) {
 46        vetoEvent;
 47      }
 48
 49      // Isolate photons with ET_sum in cone
 50      Particles isolated_photons;
 51      const Particles& fs = apply<FinalState>(event, "FS").particlesByPt();
 52      for (const Particle& photon : photons) {
 53        FourMomentum mom_in_cone;
 54        double eta_P = photon.eta();
 55        double phi_P = photon.phi();
 56        for (const Particle& p : fs) {
 57          if (deltaR(eta_P, phi_P, p.eta(), p.phi()) < 0.4) {
 58            mom_in_cone += p.momentum();
 59          }
 60        }
 61        if (mom_in_cone.Et()-photon.Et() < 4.0*GeV) {
 62          isolated_photons.push_back(photon);
 63        }
 64      }
 65
 66      if (isolated_photons.size() != 2) {
 67        vetoEvent;
 68      }
 69
 70      _h_pT_P1->fill(isolated_photons[0].pT(), weight);
 71      _h_pT_P2->fill(isolated_photons[1].pT(), weight);
 72      FourMomentum mom_PP = isolated_photons[0].momentum() + isolated_photons[1].momentum();
 73      _h_m_PP->fill(mom_PP.mass(), weight);
 74      _h_pT_PP->fill(mom_PP.pT(), weight);
 75      _h_dphi_PP->fill(deltaPhi(isolated_photons[0].phi(),
 76                                isolated_photons[1].phi()), weight);
 77    }
 78
 79
 80    void finalize() {
 81      scale(_h_m_PP, crossSection()/sumOfWeights());
 82      scale(_h_pT_PP, crossSection()/sumOfWeights());
 83      scale(_h_pT_P1, crossSection()/sumOfWeights());
 84      scale(_h_pT_P2, crossSection()/sumOfWeights());
 85      scale(_h_dphi_PP, crossSection()/sumOfWeights());
 86    }
 87
 88    //@}
 89
 90
 91  private:
 92
 93    /// @name Histograms
 94    //@{
 95    Histo1DPtr _h_m_PP;
 96    Histo1DPtr _h_pT_PP;
 97    Histo1DPtr _h_pT_P1;
 98    Histo1DPtr _h_pT_P2;
 99    Histo1DPtr _h_dphi_PP;
100    //@}
101
102
103  };
104
105
106
107  // The hook for the plugin system
108  RIVET_DECLARE_PLUGIN(MC_DIPHOTON);
109
110}