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CMS_2016_I1473674

Measurement of the differential cross sections for top quark pair production as a function of kinematic event variables at sqrt(s) = 8 TeV
Experiment: CMS (LHC)
Inspire ID: 1473674
Status: VALIDATED
Authors:
  • Markus Seidel
  • Lukas Kreczko
  • Emyr Clement
References: Beams: p+ p+
Beam energies: (4000.0, 4000.0) GeV
Run details:
  • ttbar events at sqrt(s) = 8 TeV (inclusive or lepton+jets decay mode) Top quarks are expected in the event record to identify the decay mode.

Measurements are reported of the normalized differential cross sections for top quark pair production with respect to four kinematic event variables: the missing transverse energy; the scalar sum of the jet transverse momentum (pT); the scalar sum of the pT of all objects in the event; and the pT of leptonically decaying W bosons from top quark decays.

Source code: CMS_2016_I1473674.cc
  1#include "Rivet/Analysis.hh"
  2#include "Rivet/Projections/FinalState.hh"
  3#include "Rivet/Projections/FastJets.hh"
  4#include "Rivet/Projections/PartonicTops.hh"
  5#include "Rivet/Projections/LeptonFinder.hh"
  6#include "Rivet/Projections/IdentifiedFinalState.hh"
  7#include "Rivet/Projections/PromptFinalState.hh"
  8#include "Rivet/Projections/VetoedFinalState.hh"
  9#include "Rivet/Projections/InvMassFinalState.hh"
 10#include "Rivet/Projections/MissingMomentum.hh"
 11
 12namespace Rivet {
 13
 14
 15  class CMS_2016_I1473674 : public Analysis {
 16  public:
 17
 18    // Minimal constructor
 19    RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2016_I1473674);
 20
 21
 22    // Set up projections and book histograms
 23    void init() {
 24
 25      // Complete final state
 26      FinalState fs;
 27
 28      // Parton level top quarks
 29      declare(PartonicTops(TopDecay::E_MU, PromptEMuFromTau::NO), "LeptonicPartonTops");
 30      declare(PartonicTops(TopDecay::HADRONIC), "HadronicPartonTops");
 31
 32      // Projections for dressed electrons and muons
 33      IdentifiedFinalState photons(fs);
 34      photons.acceptIdPair(PID::PHOTON);
 35      //
 36      IdentifiedFinalState el_id(fs);
 37      el_id.acceptIdPair(PID::ELECTRON);
 38      PromptFinalState electrons(el_id);
 39      declare(electrons, "Electrons");
 40      LeptonFinder dressed_electrons(electrons, photons, 0.1);
 41      declare(dressed_electrons, "DressedElectrons");
 42      //
 43      IdentifiedFinalState mu_id(fs);
 44      mu_id.acceptIdPair(PID::MUON);
 45      PromptFinalState muons(mu_id);
 46      declare(muons, "Muons");
 47      LeptonFinder dressed_muons(muons, photons, 0.1);
 48      declare(dressed_muons, "DressedMuons");
 49
 50      // Projection for jets
 51      VetoedFinalState fs_jets;
 52      fs_jets.addVetoOnThisFinalState(dressed_muons);
 53      declare(FastJets(fs_jets, JetAlg::ANTIKT, 0.5), "Jets");
 54
 55      // Projections for MET
 56      declare(MissingMomentum(), "MET");
 57
 58
 59      // Booking of histograms
 60      book(_hist_met ,5, 1, 1);
 61      book(_hist_ht  ,6, 1, 1);
 62      book(_hist_st  ,7, 1, 1);
 63      book(_hist_wpt ,8, 1, 1);
 64    }
 65
 66
 67    /// Per-event analysis
 68    void analyze(const Event& event) {
 69
 70      // Select ttbar -> lepton+jets at parton level, removing tau decays
 71      const Particles leptonicpartontops = apply<ParticleFinder>(event, "LeptonicPartonTops").particlesByPt();
 72      if (leptonicpartontops.size() != 1) vetoEvent;
 73      const Particles hadronicpartontops = apply<ParticleFinder>(event, "HadronicPartonTops").particlesByPt();
 74      if (hadronicpartontops.size() != 1) vetoEvent;
 75
 76      // Select ttbar -> lepton+jets at particle level
 77      const LeptonFinder& dressed_electrons = apply<LeptonFinder>(event, "DressedElectrons");
 78      const LeptonFinder& dressed_muons = apply<LeptonFinder>(event, "DressedMuons");
 79      if (dressed_electrons.dressedLeptons().size() + dressed_muons.dressedLeptons().size() != 1) vetoEvent;
 80      const FourMomentum lepton = (dressed_electrons.dressedLeptons().empty() ? dressed_muons : dressed_electrons).dressedLeptons()[0];
 81
 82      // MET
 83      const MissingMomentum& met = apply<MissingMomentum>(event, "MET");
 84      _hist_met->fill(met.visibleMomentum().pT()/GeV);
 85
 86      // HT and ST
 87      const FastJets& jetpro = apply<FastJets>(event, "Jets");
 88      const Jets jets = jetpro.jetsByPt(Cuts::pT > 20*GeV);
 89
 90      double ht = 0.0;
 91      for (const Jet& j : jets) {
 92        if (deltaR(j.momentum(), lepton) > 0.3) {
 93          ht += j.pT();
 94        }
 95      }
 96
 97      double st = ht + lepton.pT() + met.visibleMomentum().pT();
 98      _hist_ht->fill(ht/GeV);
 99      _hist_st->fill(st/GeV);
100
101      // WPT
102      const FourMomentum w = lepton - met.visibleMomentum();
103      _hist_wpt->fill(w.pT()/GeV);
104    }
105
106
107    /// Normalize histograms
108    void finalize() {
109      normalize(_hist_met);
110      normalize(_hist_ht);
111      normalize(_hist_st);
112      normalize(_hist_wpt);
113    }
114
115  private:
116    Histo1DPtr _hist_met, _hist_ht, _hist_st, _hist_wpt;
117
118  };
119
120
121  RIVET_DECLARE_PLUGIN(CMS_2016_I1473674);
122
123}