Rivet analyses

title: ATLAS_2017_I1604271

ATLAS Inclusive jet cross section measurement at sqrt(s)=8TeV

Experiment: ATLAS (LHC)

Inspire ID: 1604271

Status: VALIDATED

Authors: - Jon Butterworth - Jonathan Bossio - Zdenek Hubacek

References: - Expt page: ATLAS-STDM-2015-01 - JHEP 09 (2017) 020 - arXiv: 1706.03192

Beams: p+ p+

Beam energies: (4000.0, 4000.0)GeV

Run details: - LHC 8TeV, ATLAS, QCD jet production, anti-kt R=0.4 jets, anti-kt R=0.6 jets

Inclusive jet production cross-sections are measured in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=8$ TeV recorded by the ATLAS experiment at the Large Hadron Collider at CERN. The total integrated luminosity of the analysed data set amounts to 20.2 fb$^{-1}$. Double-differential cross-sections are measured for jets defined by the anti-$k_\text{t}$ jet clustering algorithm with radius parameters of $R=0.4$ and $R=0.6$ and are presented as a function of the jet transverse momentum, in the range between 70 GeV and 2.5 TeV and in six bins of the absolute jet rapidity, between 0 and 3.0. The measured cross-sections are compared to predictions of quantum chromodynamics, calculated at next-to-leading order in perturbation theory, and corrected for non-perturbative and electroweak effects. The level of agreement with predictions, using a selection of different parton distribution functions for the proton, is quantified. Tensions between the data and the theory predictions are observed.

Source code:ATLAS_2017_I1604271.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief Inclusive jets at 8 TeV class ATLAS_2017_I1604271 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2017_I1604271);

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

  const FinalState fs;
  declare(fs, "FinalState");
  FastJets fj04(fs, JetAlg::ANTIKT, 0.4);
  FastJets fj06(fs, JetAlg::ANTIKT, 0.6);
  fj04.useInvisibles();
  declare(fj04, "AntiKT04");
  fj06.useInvisibles();
  declare(fj06, "AntiKT06");

  // |y| and ystar bins
  const vector<double> ybins{0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0};

  // Book histograms
  // pT histograms
  book(_pThistograms6, ybins);
  book(_pThistograms4, ybins);
  for (size_t i = 0; i < _pThistograms4->numBins(); ++i) {
    book(_pThistograms6->bin(i + 1), i + 1, 1, 1);
    book(_pThistograms4->bin(i + 1), i + 7, 1, 1);
  }
}


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

  const Jets& kt4Jets = apply<FastJets>(event, "AntiKT04")
                            .jetsByPt(Cuts::pT > 70 * GeV && Cuts::absrap < 3.0);
  const Jets& kt6Jets = apply<FastJets>(event, "AntiKT06")
                            .jetsByPt(Cuts::pT > 70 * GeV && Cuts::absrap < 3.0);

  int nJets4 = kt4Jets.size();
  int nJets6 = kt6Jets.size();

  // Inclusive jet selection
  for (int ijet = 0; ijet < nJets4; ++ijet) { // loop over jets
    FourMomentum jet = kt4Jets[ijet].momentum();
    // pT selection
    const double absy = jet.absrap();
    _pThistograms4->fill(absy, jet.pt() / GeV);
  }

  for (int ijet = 0; ijet < nJets6; ++ijet) { // loop over jets
    FourMomentum jet = kt6Jets[ijet].momentum();
    // pT selection
    const double absy = jet.absrap();
    _pThistograms6->fill(absy, jet.pt() / GeV);
  }
}


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

  const double xs_norm_factor = 0.5 * crossSection() / picobarn / sumOfWeights();

  scale(_pThistograms4, xs_norm_factor);
  scale(_pThistograms6, xs_norm_factor);
  divByGroupWidth({_pThistograms4, _pThistograms6});
}

private:

// The inclusive pT spectrum for akt4 jets
Histo1DGroupPtr _pThistograms4;
// The inclusive pT spectrum for akt6 jets
Histo1DGroupPtr _pThistograms6;

};

RIVET_DECLARE_PLUGIN(ATLAS_2017_I1604271);

} ```