Rivet analyses

Z+jet at 8 TeV

Experiment: ATLAS (LHC)

Inspire ID: 1744201

Status: VALIDATED

Authors: - Aliaksei Hrynevich - Deepak Kar

References: - Expt page: ATLAS-STDM-2016-11 - arXiv: 1907.06728

Beams: p+ p+

Beam energies: (4000.0, 4000.0)GeV

Run details: - pp -> Z(ee)+jets at 8 TeV

The inclusive cross-section for jet production in association with a Z boson decaying into an electron-positron pair is measured as a function of the transverse momentum and the absolute rapidity of jets using 19.9 fb⁻¹ of $\sqrt{s}=8$ TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. The measured Z+ jets cross-section is unfolded to the particle level. The cross-section is compared with state-of-the-art Standard Model calculations, including the next-to-leading-order and next-to-next-to-leading-order perturbative QCD calculations, corrected for non-perturbative and QED radiation effects. The results of the measurements cover final-state jets with transverse momenta up to 1 TeV, and show good agreement with fixed-order calculations.

Source code:`ATLAS_2019_I1744201.cc`

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/DileptonFinder.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/FinalState.hh"

namespace Rivet {


  /// Z+jet at 8 TeV
  class ATLAS_2019_I1744201 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2019_I1744201);


    void init() {

      DileptonFinder zfinder_el(91.2 * GeV, 0.1,
                                Cuts::abseta < 2.47 && Cuts::pT > 20 * GeV && Cuts::abspid == PID::ELECTRON,
                                Cuts::massIn(66 * GeV, 116 * GeV));
      declare(zfinder_el, "DileptonFinder_el");

      declare(FastJets(zfinder_el.remainingFinalState(), JetAlg::ANTIKT, 0.4, JetMuons::NONE,
                       JetInvisibles::NONE),
              "AKT04");

      h_jet_y_pt.resize(6);
      for (size_t iPtBin = 0; iPtBin < h_jet_y_pt.size(); ++iPtBin) {
        book(h_jet_y_pt[iPtBin], iPtBin + 2, 1, 1);
      }
    }


    void analyze(const Event& event) {

      // electrons selection
      const DileptonFinder& zfinder = apply<DileptonFinder>(event, "DileptonFinder_el");
      if (zfinder.bosons().size() != 1) vetoEvent;

      const Particles& leptons = zfinder.constituents();
      if (leptons.size() != 2) vetoEvent;

      if (deltaR(leptons[0], leptons[1]) < 0.2) vetoEvent;


      // jets selection
      Jets jets = apply<FastJets>(event, "AKT04").jetsByPt(Cuts::pT > 25 * GeV && Cuts::absrap < 3.4);
      idiscardIfAnyDeltaRLess(jets, leptons, 0.4);
      if (jets.empty()) vetoEvent; // require at least one jet in event

      for (const Jet& jet : jets) {
        const double jet_pt = jet.pT() / GeV;
        for (size_t iPtBin = 0; iPtBin < (ptBins.size() - 1); ++iPtBin) {
          if (jet_pt >= ptBins[iPtBin] && jet_pt < ptBins[iPtBin + 1]) {
            h_jet_y_pt[iPtBin]->fill(jet.absrap());
          }
        }
      }
    }

    void finalize() {

      const double norm = crossSection() / femtobarn / sumOfWeights();
      for (int iPtBin = 0; iPtBin < 6; ++iPtBin) {
        scale(h_jet_y_pt[iPtBin], norm / (ptBins[iPtBin + 1] - ptBins[iPtBin]));
      }
    }

  protected:

    vector<double> ptBins = {25., 50., 100., 200., 300., 400., 1050.};

  private:

    vector<Histo1DPtr> h_jet_y_pt;
  };

  RIVET_DECLARE_PLUGIN(ATLAS_2019_I1744201);
}

Rivet analyses

Z+jet at 8 TeV

Source code:ATLAS_2019_I1744201.cc

Source code:`ATLAS_2019_I1744201.cc`