Rivet analyses

title: CMS_2020_I1794169

Measurements of production cross sections of WZ and same-sign WW boson pairs in association with two jets in proton-proton collisions at $\sqrt{s} =$ 13 TeV

Experiment: CMS (LHC)

Inspire ID: 1794169

Status: VALIDATED

Authors: - cms-pag-conveners-smp@cern.ch - Guillelmo Gomez-Ceballos - Kenneth Long

References: - arXiv: 2005.01173 - Expt page: CMS-SMP-19-012 - Phys. Lett. B 809 (2020) 135710

Beams: p+ p+

Beam energies: (6500.0, 6500.0)GeV

Run details: - VBS WZ and W+W+ interactions at $\sqrt{s} = 13$ TeV. Data collected by CMS during the year 2016-18.

Measurements of production cross sections of WZ and same-sign W+W+ boson pairs in association with two jets in proton-proton collisions at sqrt{s}=13TeV at the LHC are reported. The data sample corresponds to an integrated luminosity of 137fb-1, collected with the CMS detector during 2016--2018. The measurements are performed in the leptonic decay modes. Differential fiducial cross sections as functions of the invariant masses of the jet and charged lepton pairs, as well as of the leading-lepton transverse momentum, are measured for WW production and are consistent with the standard model predictions. The dependence of differential cross sections on the invariant mass of the jet pair is also measured for WZ production. An observation of electroweak production of WZ boson pairs is reported with an observed (expected) significance of 6.8 (5.3) standard deviations. Constraints are obtained on the structure of quartic vector boson interactions in the framework of effective field theory.

Source code:CMS_2020_I1794169.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/LeptonFinder.hh"

include "Rivet/Projections/MissingMomentum.hh"

include "Rivet/Projections/PromptFinalState.hh"

namespace Rivet {

/// @brief Production cross-sections of WZ and same-sign WW with two jets in pp collisions at 13 TeV class CMS_2020_I1794169 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2020_I1794169);


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

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

  // Initialise and register projections
  _mode = 0;
  if (getOption("LMODE") == "WZ") _mode = 1;

  // The basic final-state projection:
  // all final-state particles within
  // the given eta acceptance
  const FinalState fs(Cuts::abseta < 4.9);
  const FinalState fsjet4p7(Cuts::abseta < 4.7);

  // The final-state particles declared above are clustered using FastJet with
  // the anti-kT algorithm and a jet-radius parameter 0.4
  // muons and neutrinos are excluded from the clustering
  FastJets jet4p7fs(fsjet4p7, JetAlg::ANTIKT, 0.4);
  declare(jet4p7fs, "jets4p7");

  // FinalState of prompt photons and bare muons and electrons in the event
  PromptFinalState photons(Cuts::abspid == PID::PHOTON);
  PromptFinalState bare_leps(Cuts::abspid == PID::MUON || Cuts::abspid == PID::ELECTRON);
  bare_leps.acceptTauDecays(false);

  // Dress the prompt bare leptons with prompt photons within dR < 0.1,
  // and apply some fiducial cuts on the dressed leptons
  Cut lepton_cuts = Cuts::abseta < 2.5 && Cuts::pT > 20 * GeV;
  LeptonFinder dressed_leps(bare_leps, photons, 0.1, lepton_cuts);
  declare(dressed_leps, "leptons");

  // Missing momentum
  declare(MissingMomentum(fs), "MET");

  // Book histograms
  book(_h_WW_mjj, 9, 1, 1);
  book(_h_WW_mll, 11, 1, 1);
  book(_h_WW_ptlmax, 13, 1, 1);
  book(_h_WZ_mjj, 15, 1, 1);
}

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

  // Retrieve dressed leptons, sorted by pT
  Particles leptons = apply<LeptonFinder>(event, "leptons").particlesByPt();

  // Apply a #leptons requirement
  if (leptons.size() <= 1 || leptons.size() >= 4) return;

  // Retrieve clustered jets, sorted by pT, with a minimum pT cut
  Jets jets50 = apply<FastJets>(event, "jets4p7").jetsByPt(Cuts::pT > 50 * GeV);

  // Remove all jets within dR < 0.4 of a dressed lepton
  idiscardIfAnyDeltaRLess(jets50, leptons, 0.4);

  // Apply a njets >= 2 cut
  if (jets50.size() < 2) return;

  FourMomentum dijetCand = jets50[0].momentum() + jets50[1].momentum();
  double deltaEtaJJ = std::abs(jets50[0].eta() - jets50[1].eta());

  // Apply a mjj > 500 and detajj > 2.5 cuts
  if (dijetCand.mass() <= 500 * GeV || deltaEtaJJ <= 2.5) return;

  // W+W+ selection
  if (leptons.size() == 2 && leptons[0].pid() * leptons[1].pid() > 0 && _mode == 0) {
    FourMomentum dilCand = leptons[0].momentum() + leptons[1].momentum();
    if (dilCand.mass() > 20 * GeV) {
      double ptlmax = leptons[0].pt();
      double ptlmin = leptons[1].pt();
      if (ptlmax < ptlmin) {
        ptlmax = leptons[1].pt();
        ptlmin = leptons[0].pt();
      }

      _h_WW_mjj->fill(min(dijetCand.mass() / GeV, 2999.999));
      _h_WW_mll->fill(min(dilCand.mass() / GeV, 499.999));
      _h_WW_ptlmax->fill(min(ptlmax / GeV, 299.999));
    }
  }

  // WZ selection
  else if (leptons.size() == 3 && _mode == 1) {
    double mllZ = 10000;
    int iW = -1;
    if (leptons[0].pid() * leptons[1].pid() < 0 && leptons[0].abspid() == leptons[1].abspid()
        && fabs((leptons[0].momentum() + leptons[1].momentum()).mass() - 91.1876 * GeV)
            < fabs(mllZ - 91.1876 * GeV)) {
      mllZ = (leptons[0].momentum() + leptons[1].momentum()).mass();
      iW = 2;
    }

    if (leptons[0].pid() * leptons[2].pid() < 0 && leptons[0].abspid() == leptons[2].abspid()
        && fabs((leptons[0].momentum() + leptons[2].momentum()).mass() - 91.1876 * GeV)
            < fabs(mllZ - 91.1876 * GeV)) {
      mllZ = (leptons[0].momentum() + leptons[2].momentum()).mass();
      iW = 1;
    }

    if (leptons[1].pid() * leptons[2].pid() < 0 && leptons[1].abspid() == leptons[2].abspid()
        && fabs((leptons[1].momentum() + leptons[2].momentum()).mass() - 91.1876 * GeV)
            < fabs(mllZ - 91.1876 * GeV)) {
      mllZ = (leptons[1].momentum() + leptons[2].momentum()).mass();
      iW = 0;
    }

    // Plot
    if (iW >= 0 && fabs(mllZ - 91.1876 * GeV) < 15 * GeV) {
      _h_WZ_mjj->fill(min(dijetCand.mass() / GeV, 2999.999));
    }
  }
}


/// @todo Replace with barchart()
void normalizeToSum(Histo1DPtr hist) {
  for (size_t i = 0; i < hist->numBins(); ++i) {
    float width = hist->bin(i).xWidth();
    hist->bin(i).scaleW(width != 0 ? width : 1.);
  }
  if (hist->integral() > 0) scale(hist, 1. / hist->integral());
}


/// Normalise histograms etc., after the run
void finalize() {
  double norm = (sumOfWeights() != 0) ? crossSection() / femtobarn / sumOfWeights() : 1.0;
  scale(_h_WW_mjj, norm);
  scale(_h_WW_mll, norm);
  scale(_h_WW_ptlmax, norm);
  scale(_h_WZ_mjj, norm);
}

private:

/// Lepton-mode flag
size_t _mode;

/// @name Histograms
/// @{
Histo1DPtr _h_WW_mjj, _h_WW_mll, _h_WW_ptlmax, _h_WZ_mjj;
/// @}

};

RIVET_DECLARE_PLUGIN(CMS_2020_I1794169);

} ```