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Rivet analyses reference

ATLAS_2019_I1744201

Z+jet at 8 TeV
Experiment: ATLAS (LHC)
Inspire ID: 1744201
Status: VALIDATED
Authors:
  • Aliaksei Hrynevich
  • Deepak Kar
References: 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
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FastJets.hh"
 4#include "Rivet/Projections/DileptonFinder.hh"
 5#include "Rivet/Projections/FinalState.hh"
 6
 7namespace Rivet{
 8
 9
10  /// Z+jet at 8 TeV
11  class ATLAS_2019_I1744201 : public Analysis {
12  public:
13
14    /// Constructor
15    RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2019_I1744201);
16
17
18    void init() {
19
20      DileptonFinder zfinder_el(91.2*GeV, 0.1, Cuts::abseta < 2.47 && Cuts::pT > 20*GeV &&
21                                Cuts::abspid == PID::ELECTRON, Cuts::massIn(66*GeV, 116*GeV));
22      declare(zfinder_el, "DileptonFinder_el");
23
24      declare(FastJets(zfinder_el.remainingFinalState(), JetAlg::ANTIKT, 0.4,
25                       JetMuons::NONE, JetInvisibles::NONE), "AKT04");
26
27      h_jet_y_pt.resize(6);
28      for (size_t iPtBin=0; iPtBin < h_jet_y_pt.size(); ++iPtBin) {
29        book(h_jet_y_pt[iPtBin], iPtBin+2, 1, 1);
30      }
31
32    }
33
34
35    void analyze(const Event& event) {
36
37      // electrons selection
38      const DileptonFinder& zfinder = apply<DileptonFinder>(event, "DileptonFinder_el");
39      if ( zfinder.bosons().size() != 1)  vetoEvent;
40
41      const Particles& leptons = zfinder.constituents();
42      if ( leptons.size() != 2)  vetoEvent;
43
44      if (deltaR(leptons[0], leptons[1]) < 0.2)  vetoEvent;
45
46
47      // jets selection
48      Jets jets = apply<FastJets>(event, "AKT04").jetsByPt( Cuts::pT > 25*GeV && Cuts::absrap < 3.4 );
49      idiscardIfAnyDeltaRLess(jets, leptons, 0.4);
50      if (jets.empty())  vetoEvent;  // require at least one jet in event
51
52      for (const Jet& jet : jets) {
53        const double jet_pt = jet.pT() / GeV;
54        for(size_t iPtBin = 0; iPtBin < (ptBins.size() - 1); ++iPtBin) {
55          if (jet_pt >= ptBins[iPtBin] && jet_pt < ptBins[iPtBin+1]) {
56            h_jet_y_pt[iPtBin]->fill(jet.absrap());
57          }
58        }
59	    }
60   }
61
62  void finalize() {
63
64    const double norm = crossSection()/femtobarn/sumOfWeights();
65    for(int iPtBin=0; iPtBin < 6; ++iPtBin){
66    	scale(h_jet_y_pt[iPtBin], norm / ( ptBins[iPtBin+1] - ptBins[iPtBin] ));
67    }
68
69  }
70
71   protected:
72
73     vector<double> ptBins = { 25., 50., 100., 200., 300., 400., 1050. };
74
75   private:
76     vector<Histo1DPtr> h_jet_y_pt;
77
78  };
79
80  RIVET_DECLARE_PLUGIN(ATLAS_2019_I1744201);
81}