Rivet analyses

title: CMS_2020_I1776758

Ratios of cross sections in the associated production of a Z boson with at least one charm or bottom quark jet are measured in proton-proton collisions at $\sqrt{s}=13$ TeV

Experiment: CMS (LHC)

Inspire ID: 1776758

Status: VALIDATED

Authors: - Hannes Jung

References: - Phys.Rev.D 102 (2020) 3 032007 - DOI:10.1103/PhysRevD.102.032007 - arXiv: 2001.06899 - Expt page: CMS-SMP-19-004

Beams: p+ p+

Beam energies: (6500.0, 6500.0)GeV

Run details: - Z to leptons

Ratios of cross sections, $\sigma(Z+c~jets)/\sigma(Z+jets)$, $\sigma(Z+b~jets)/\sigma(Z+jets)$ and $\sigma(Z+c~jets)/\sigma(Z+b~jets)$ in the associated production of a Z boson with at least one charm or bottom quark jet are measured in proton-proton collisions at $\sqrt{s}=13$ TeV. The data sample, collected by the CMS experiment at the CERN LHC, corresponds to an integrated luminosity of 35.9 $fv^{-1}$, with a fiducial volume of $p_T > 30 $ GeV and $|\eta|<2.4$ for the jets. The Z boson candidates come from leptonic decays into electrons or muons with $p_T > 25 $ GeV and $|\eta|<2.4$ and the dilepton mass satisfies $ 71 < M_Z < 111 $ GeV.

Source code:CMS_2020_I1776758.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/DileptonFinder.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/LeptonFinder.hh"

include "Rivet/Projections/VetoedFinalState.hh"

include "Rivet/Tools/Cuts.hh"

namespace Rivet {

/// @brief Ratios of cross-sections in Z + >= 1 c- or b-jet at 13 TeV class CMS_2020_I1776758 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2020_I1776758);


// based on SMP_19_004

/// @name Analysis methods
///@{

/// Book histograms and initialise projections before the run
void init() {

  // Initialise and register projections
  DileptonFinder zeeFinder(91.2 * GeV, 0.1,
                           Cuts::abseta < 2.4 && Cuts::pT > 25 * GeV && Cuts::abspid == PID::ELECTRON,
                           Cuts::massIn(71 * GeV, 111 * GeV));
  declare(zeeFinder, "ZeeFinder");

  DileptonFinder zmumuFinder(91.2 * GeV, 0.1,
                             Cuts::abseta < 2.4 && Cuts::pT > 25 * GeV && Cuts::abspid == PID::MUON,
                             Cuts::massIn(71 * GeV, 111 * GeV));
  declare(zmumuFinder, "ZmumuFinder");

  VisibleFinalState visfs;
  VetoedFinalState jetConstits(visfs);
  jetConstits.addVetoOnThisFinalState(zeeFinder);
  jetConstits.addVetoOnThisFinalState(zmumuFinder);

  FastJets akt04Jets(jetConstits, JetAlg::ANTIKT, 0.4);
  declare(akt04Jets, "AntiKt04Jets");

  book(_h_jet_pt_combined, "_TMP/jet_pt_combined", refData(1, 1, 1));
  book(_h_jet_pt_cjet_combined, "_TMP/jet_pt_cjet_combined", refData(1, 1, 1));
  book(_h_jet_pt_bjet_combined, "_TMP/jet_pt_bjet_combined", refData(1, 1, 1));

  book(_h_Z_pt_combined, "_TMP/Z_pt_combined", refData(2, 1, 1));
  book(_h_Z_pt_cjet_combined, "_TMP/Z_pt_cjet_combined", refData(2, 1, 1));
  book(_h_Z_pt_bjet_combined, "_TMP/Z_pt_bjet_combined", refData(2, 1, 1));

  // book ratio histos

  book(_h_R_jet_pt_cjet_combined, 1, 1, 1);
  book(_h_R_jet_pt_bjet_combined, 3, 1, 1);
  book(_h_R_jet_pt_cb_combined, 5, 1, 1);

  book(_h_R_Z_pt_cjet_combined, 2, 1, 1);
  book(_h_R_Z_pt_bjet_combined, 4, 1, 1);
  book(_h_R_Z_pt_cb_combined, 6, 1, 1);
}


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

  const DileptonFinder& zeeFS = apply<DileptonFinder>(event, "ZeeFinder");
  const DileptonFinder& zmumuFS = apply<DileptonFinder>(event, "ZmumuFinder");

  const Particles& zees = zeeFS.bosons();
  const Particles& zmumus = zmumuFS.bosons();

  // We did not find exactly one Z. No good.
  if (zees.size() + zmumus.size() != 1) {
    MSG_DEBUG("Did not find exactly one good Z candidate");
    vetoEvent;
  }

  //event identification depending on mass window
  bool ee_event = false;
  bool mm_event = false;

  if (zees.size() == 1) {
    ee_event = true;
  }
  if (zmumus.size() == 1) {
    mm_event = true;
  }
  if (!(ee_event || mm_event)) vetoEvent;

  // Cluster jets
  // NB. Veto has already been applied on leptons and photons used for dressing
  const FastJets& fj = apply<FastJets>(event, "AntiKt04Jets");
  Jets jets = fj.jetsByPt(Cuts::abseta < 2.4 && Cuts::pT > 30 * GeV);
  idiscardIfAnyDeltaRLess(jets, ee_event ? zees : zmumus, 0.4);

  // We don't care about events with no isolated jets
  if (jets.empty()) {
    MSG_DEBUG("No jets in event");
    vetoEvent;
  }

  Jets jc_final;
  Jets jb_final;

  //identification of bjets
  int n_ctag = 0;
  int n_btag = 0;
  for (const Jet& j : jets) {
    if (j.cTagged()) {
      n_ctag = n_ctag + 1;
    }
    if (j.bTagged()) {
      n_btag = n_btag + 1;
    }
  }

  for (const Jet& j : jets) {
    if (j.cTagged() && n_btag == 0) {
      jc_final.push_back(j);
    }
    if (j.bTagged()) {
      jb_final.push_back(j);
    }
  }
  //histogram filling

  if ((ee_event || mm_event) && jets.size() > 0) {

    FourMomentum j1(jets[0].momentum());

    if (ee_event) {
      _h_Z_pt_combined->fill(zees[0].pt() / GeV);
      _h_jet_pt_combined->fill(j1.pt() / GeV);
    }
    if (mm_event) {
      _h_Z_pt_combined->fill(zmumus[0].pt() / GeV);
      _h_jet_pt_combined->fill(j1.pt() / GeV);
    }


    if (jc_final.size() > 0) {
      FourMomentum c1(jc_final[0].momentum());
      _h_jet_pt_cjet_combined->fill(c1.pt() / GeV);
      if (ee_event) {
        _h_Z_pt_cjet_combined->fill(zees[0].pt() / GeV);
      }
      if (mm_event) {
        _h_Z_pt_cjet_combined->fill(zmumus[0].pt() / GeV);
      }
    }
    if (jb_final.size() > 0) {
      FourMomentum b1(jb_final[0].momentum());
      _h_jet_pt_bjet_combined->fill(b1.pt() / GeV);
      if (ee_event) {
        _h_Z_pt_bjet_combined->fill(zees[0].pt() / GeV);
      }
      if (mm_event) {
        _h_Z_pt_bjet_combined->fill(zmumus[0].pt() / GeV);
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {

  divide(_h_jet_pt_cjet_combined, _h_jet_pt_combined, _h_R_jet_pt_cjet_combined);
  divide(_h_jet_pt_bjet_combined, _h_jet_pt_combined, _h_R_jet_pt_bjet_combined);
  divide(_h_jet_pt_cjet_combined, _h_jet_pt_bjet_combined, _h_R_jet_pt_cb_combined);

  divide(_h_Z_pt_cjet_combined, _h_Z_pt_combined, _h_R_Z_pt_cjet_combined);
  divide(_h_Z_pt_bjet_combined, _h_Z_pt_combined, _h_R_Z_pt_bjet_combined);
  divide(_h_Z_pt_cjet_combined, _h_Z_pt_bjet_combined, _h_R_Z_pt_cb_combined);
}

///@}


/// @name Histograms

Histo1DPtr _h_jet_pt_combined;
Histo1DPtr _h_jet_pt_cjet_combined;
Histo1DPtr _h_jet_pt_bjet_combined;
Histo1DPtr _h_Z_pt_combined, _h_Z_pt_cjet_combined, _h_Z_pt_bjet_combined;


Estimate1DPtr _h_R_jet_pt_cjet_combined, _h_R_jet_pt_bjet_combined, _h_R_jet_pt_cb_combined;


Estimate1DPtr _h_R_Z_pt_cjet_combined, _h_R_Z_pt_bjet_combined, _h_R_Z_pt_cb_combined;

};

RIVET_DECLARE_PLUGIN(CMS_2020_I1776758);

} ```