Rivet analyses

title: CMS_2018_I1662081

Measurement of the differential cross sections of top quark pair production as a function of kinematic event variables in pp collisions at sqrt(s) = 13 TeV

Experiment: CMS (LHC)

Inspire ID: 1662081

Status: VALIDATED

Authors: - Doug Burns - Emyr Clement - Markus Seidel

References: - TOP-16-014 - arxiv:1803.03991 - Submitted to JHEP

Beams: p+ p+

Beam energies: (6500.0, 6500.0)GeV

Run details: - ttbar events at sqrt(s) = 13 TeV, lepton+jets selection at particle level

Abstract : Measurements of the differential $t\overline{t}$ production cross section are presented in the single-lepton decay channel, with respect to a number of global event observables. The measurements are performed with $\text{35.9~fb}^{-1}$ of proton-proton collision data collected by the CMS experiment at the LHC during 2016 at $\sqrt{s} = \text{13~TeV}$. The differential cross sections are measured at the level of long-lived generated particles in a phase space similar to that accessible by the CMS detector, and are compared to state-of-the-art leading-order and next-to-leading-order $t\overline{t}$ simulations. Rivet : This analysis is to be run on $t\bar{t}$ simulation. The particle level selection requires: - exactly one electron or muon with $p_{T} > 26$~GeV and $|\eta| < 2.4$ - no additional electrons or muons with $p_{T} > 15$~GeV and $|\eta| < 2.4$ - at least three jets with $p_{T} > 30$~GeV and $|\eta| < 2.4$, and one jet with $p_{T} > 25$~GeV and $|\eta| < 2.4$ - two of these selected jets must be tagged as originating from a $b$ quark.

Source code:CMS_2018_I1662081.cc

```c++

include "Rivet/Analysis.hh"

include "Rivet/Projections/ChargedLeptons.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/IdentifiedFinalState.hh"

include "Rivet/Projections/LeptonFinder.hh"

include "Rivet/Projections/MissingMomentum.hh"

include "Rivet/Projections/PromptFinalState.hh"

include "Rivet/Projections/VetoedFinalState.hh"

namespace Rivet {

class CMS_2018_I1662081 : public Analysis { public:

// Minimal constructor
CMS_2018_I1662081()
    : Analysis("CMS_2018_I1662081") { }


// Set up projections and book histograms
void init() {
  // Complete final state
  FinalState fs(Cuts::abseta < 5);

  // Dressed leptons
  ChargedLeptons charged_leptons(fs);
  IdentifiedFinalState photons(fs, PID::PHOTON);

  PromptFinalState prompt_leptons(charged_leptons);
  prompt_leptons.acceptMuonDecays(true);
  prompt_leptons.acceptTauDecays(true);
  PromptFinalState prompt_photons(photons);
  prompt_photons.acceptMuonDecays(true);
  prompt_photons.acceptTauDecays(true);
  Cut looseLeptonCuts = Cuts::pt > 15 * GeV && Cuts::abseta < 2.4;

  LeptonFinder dressed_leptons(prompt_leptons, prompt_photons, 0.1, looseLeptonCuts);
  declare(dressed_leptons, "LeptonFinder");

  // Projection for jets
  VetoedFinalState fsForJets(fs);
  fsForJets.addVetoOnThisFinalState(dressed_leptons);
  declare(FastJets(fsForJets, JetAlg::ANTIKT, 0.4), "Jets");

  // Projections for MET
  declare(MissingMomentum(fs), "MET");

  // Booking of histograms
  book(_hist_norm_met, 4, 1, 1);
  book(_hist_norm_ht, 2, 1, 1);
  book(_hist_norm_st, 3, 1, 1);
  book(_hist_norm_wpt, 5, 1, 1);
  book(_hist_norm_njets, 1, 1, 1);
  book(_hist_norm_lpt, 6, 1, 1);
  book(_hist_norm_labseta, 7, 1, 1);

  book(_hist_abs_met, 11, 1, 1);
  book(_hist_abs_ht, 9, 1, 1);
  book(_hist_abs_st, 10, 1, 1);
  book(_hist_abs_wpt, 12, 1, 1);
  book(_hist_abs_njets, 8, 1, 1);
  book(_hist_abs_lpt, 13, 1, 1);
  book(_hist_abs_labseta, 14, 1, 1);
}


// per event analysis
void analyze(const Event& event) {

  // Lepton veto selection
  const LeptonFinder& dressed_leptons = apply<LeptonFinder>(event, "LeptonFinder");
  if (dressed_leptons.dressedLeptons().size() != 1) vetoEvent;

  // Signal lepton selection
  FourMomentum lepton = dressed_leptons.dressedLeptons()[0];

  const double leptonPt = lepton.pT();
  const double leptonAbsEta = std::abs(lepton.eta());
  if (leptonPt <= 26 * GeV || leptonAbsEta >= 2.4) vetoEvent;

  // Jet selection
  const FastJets& jetpro = apply<FastJets>(event, "Jets");
  const Jets jets = jetpro.jets(Cuts::abseta < 2.4 && Cuts::pT > 20 * GeV);
  Jets cleanedJets;
  unsigned int nJetsAbove30GeV = 0;
  unsigned int nJetsAbove20GeV = 0;
  unsigned int nBJetsAbove30GeV = 0;
  unsigned int nBJetsAbove20GeV = 0;
  for (const Jet& j : jets) {
    cleanedJets.push_back(j);
    ++nJetsAbove20GeV;
    if (j.pT() > 30 * GeV) ++nJetsAbove30GeV;

    if (j.bTagged()) {
      ++nBJetsAbove20GeV;
      if (j.pT() > 30 * GeV) ++nBJetsAbove30GeV;
    }
  }

  if (nJetsAbove30GeV < 3 || nJetsAbove20GeV < 4) vetoEvent;
  if (nBJetsAbove30GeV < 1 || nBJetsAbove20GeV < 2) vetoEvent;

  // MET
  const MissingMomentum& met = apply<MissingMomentum>(event, "MET");
  _hist_norm_met->fill(met.visibleMomentum().pT() / GeV);
  _hist_abs_met->fill(met.visibleMomentum().pT() / GeV);

  // HT and ST
  double ht = 0.0;
  for (const Jet& j : cleanedJets) ht += j.pT();

  double st = ht + lepton.pT() + met.visibleMomentum().pT();
  _hist_norm_ht->fill(ht / GeV);
  _hist_norm_st->fill(st / GeV);
  _hist_abs_ht->fill(ht / GeV);
  _hist_abs_st->fill(st / GeV);

  // WPT
  FourMomentum w = lepton - met.visibleMomentum();
  _hist_norm_wpt->fill(w.pT() / GeV);
  _hist_abs_wpt->fill(w.pT() / GeV);

  // Lepton pt and eta
  _hist_norm_lpt->fill(leptonPt / GeV);
  _hist_norm_labseta->fill(leptonAbsEta / GeV);

  _hist_abs_lpt->fill(leptonPt / GeV);
  _hist_abs_labseta->fill(leptonAbsEta / GeV);

  // NJets
  _hist_norm_njets->fill(cleanedJets.size());
  _hist_abs_njets->fill(cleanedJets.size());
}


void finalize() {
  normalize(_hist_norm_met);
  normalize(_hist_norm_ht);
  normalize(_hist_norm_st);
  normalize(_hist_norm_wpt);
  normalize(_hist_norm_njets);
  normalize(_hist_norm_lpt);
  normalize(_hist_norm_labseta);

  scale(_hist_abs_met, crossSection() / picobarn / sumOfWeights());
  scale(_hist_abs_ht, crossSection() / picobarn / sumOfWeights());
  scale(_hist_abs_st, crossSection() / picobarn / sumOfWeights());
  scale(_hist_abs_wpt, crossSection() / picobarn / sumOfWeights());
  scale(_hist_abs_njets, crossSection() / picobarn / sumOfWeights());
  scale(_hist_abs_lpt, crossSection() / picobarn / sumOfWeights());
  scale(_hist_abs_labseta, crossSection() / picobarn / sumOfWeights());
}

private:

Histo1DPtr _hist_norm_met, _hist_norm_ht, _hist_norm_st, _hist_norm_wpt, _hist_norm_njets, _hist_norm_lpt,
    _hist_norm_labseta;
Histo1DPtr _hist_abs_met, _hist_abs_ht, _hist_abs_st, _hist_abs_wpt, _hist_abs_njets, _hist_abs_lpt,
    _hist_abs_labseta;

};

RIVET_DECLARE_PLUGIN(CMS_2018_I1662081);

} ```