Rivet analyses

title: CMS_2022_I2080534

EW W+W- production at 13 TeV

Experiment: CMS (LHC)

Inspire ID: 2080534

Status: VALIDATED

Authors: - Mattia Lizzo

References: - Expt page: CMS-SMP-21-001 - Phys.Lett.B 841 (2023) 137495 - arXiv: 2205.05711

Beams: p+ p+

Beam energies: (6500.0, 6500.0)GeV

Run details: - EW production of W+W- pairs in association with two jets, each W boson decaying into l+nu final state.

An observation is reported of the electroweak production of a $W^+W^-$ pair in association with two jets, with both $W$ bosons decaying leptonically. The data sample corresponds to an integrated luminosity of 138fb$^{-1}$ of proton-proton collisions at $\sqrt{s} = 13$ TeV, collected by the CMS detector at the CERN LHC. Events are selected by requiring exactly two opposite-sign leptons (electrons or muons) and two jets with large pseudorapidity separation and high dijet invariant mass. Events are categorized based on the flavor of the final-state leptons. A signal is observed with a significance of 5.6 standard deviations (5.2 expected) with respect to the background-only hypothesis. The measured fiducial cross section is 10.2 $\pm$ 2.0 fb and this value is consistent with the standard model prediction of 9.1 $\pm$ 0.6 fb.

Source code:CMS_2022_I2080534.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 EW W+W- production at 13 TeV class CMS_2022_I2080534 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2022_I2080534);

/// @name Analysis methods
/// @{
void init() {

  // The basic final-state projection:
  // all final-state particles within
  // the given eta acceptance
  const FinalState fs(Cuts::abseta < 4.9 && Cuts::pT > 100 * MeV);

  // 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 jetfs(fs, JetAlg::ANTIKT, 0.4);
  declare(jetfs, "jets");

  // 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);

  // 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 > 10 * 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_xsec_exp, 1, 1, 1);
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  // Retrieve dressed leptons, sorted by pT
  const Particles& leptons = apply<LeptonFinder>(event, "leptons").particlesByPt();

  // Retrieve clustered jets, sorted by pT, with a minimum pT cut
  Jets jets = apply<FastJets>(event, "jets").jetsByPt(Cuts::pT > 30 * GeV && Cuts::abseta < 4.7);

  // Retrieve Etmiss variable
  const double Etmiss = apply<MissingMomentum>(event, "MET").missingEt();

  // Remove jets with dressed leptons within dR < 0.4
  idiscardIfAnyDeltaRLess(jets, leptons, 0.4);
  if (jets.size() < 2) vetoEvent;

  // Veto event if there is at least one b-jet
  for (const Jet& j : jets) {
    if (j.bTagged()) vetoEvent;
  }

  // Apply lepton cuts
  if (leptons.size() < 2) vetoEvent;
  if (leptons[0].pT() < 25 * GeV || leptons[1].pT() < 13 * GeV) vetoEvent;
  if (leptons.size() > 2 && leptons[2].pT() > 10 * GeV) vetoEvent;
  if (leptons[0].pid() * leptons[1].pid() != -11 * 13 && leptons[0].pid() * leptons[1].pid() != -11 * 11
      && leptons[0].pid() * leptons[1].pid() != -13 * 13)
    vetoEvent;

  FourMomentum l1 = leptons[0].momentum();
  FourMomentum l2 = leptons[1].momentum();
  FourMomentum ll = (l1 + l2);
  const double mll = ll.mass();

  if (ll.pT() < 30 * GeV) vetoEvent;
  if (mll < 50 * GeV) vetoEvent;

  // Apply a missing-momentum cut
  if (Etmiss < 20 * GeV) vetoEvent;

  FourMomentum j1 = jets[0].momentum();
  FourMomentum j2 = jets[1].momentum();
  const double mjj = (j1 + j2).mass();
  const double detajj = abs(j1.eta() - j2.eta());

  // Apply VBS cuts
  if (mjj < 300 * GeV || detajj < 2.5) vetoEvent;

  _h_xsec_exp->fill("Exclusive"s);
}

/// Normalise histograms etc., after the run
void finalize() {
  const double norm = crossSection() / femtobarn / sumOfWeights();

  scale(_h_xsec_exp, norm);
}

//@}

/// @name Histograms
//@{
BinnedHistoPtr<string> _h_xsec_exp;
//@}

};

RIVET_DECLARE_PLUGIN(CMS_2022_I2080534);

} // namespace Rivet ```