Rivet analyses

title: ATLAS_2019_I1744201

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++ // -- 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); } ```