Rivet Analyses Reference

ATLAS_2014_I1312627

Ratios of $V$+jets observables between $W$ and $Z$ events
Experiment: ATLAS (LHC)
Inspire ID: 1312627
Status: VALIDATED
Authors:
  • Christian Gutschow
References:Beams: p+ p+
Beam energies: (3500.0, 3500.0) GeV
Run details:
  • Inclusive $W$ and inclusive $Z$ in both electron and muon channels

Measurements of the ratio of the production cross sections for $W$ and $Z$ bosons in association with jets in proton-proton collisions at $\sqrt{s} = 7$ TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is based on the entire 2011 dataset, corresponding to an integrated luminosity of 4.6$\text{fb}^{-1}$. Inclusive and differential cross-section ratios for massive vector bosons decaying to electrons and muons are measured in association with jets with transverse momentum $p_\text{T} > 30$ GeV and jet rapidity $|y| < 4.4$. The default routine will pick up the electron decay channel of the heavy bosons and compare it to the combined (muon and electron channel) data. Individual channels (for data) are available as well, use ATLAS_2014_I1312627_EL and ATLAS_2014_I1312627_MU to specify the decay channel directly. NB #1: The "x01" Scatter2D objects are constructed from the ratio of "x02" to "x03" Histo1D objects. If several output yoda files are merged with yodamerge, the merged "x01" objects will become meaningless. New "x01" Scatter2Ds can easil be constructed in a postprocessing step from the merged "x02" (nominator) and "x03" (denominator) objects. NB #2: Special care ought to be taken when evaluating theoretical uncertainties due to potential cancellations/correlations between numerator and denominator.

Source code: ATLAS_2014_I1312627.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/WFinder.hh"
#include "Rivet/Projections/ZFinder.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/VetoedFinalState.hh"

namespace Rivet {


  /// Measurement of V+jets distributions, taken as ratios between W and Z channels
  class ATLAS_2014_I1312627 : public Analysis {
  public:

    /// @name Plotting helper types
    //@{

    struct Plots {
      string ref;
      Histo1DPtr comp[2]; // (de)nominator components
      Scatter2DPtr ratio; // Rjets plot
    };

    //@}


    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2014_I1312627);

    /// @name Analysis methods
    //@{

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

      // get option
      _mode = 0;
      if ( getOption("LMODE") == "EL" )  _mode = 1;
      if ( getOption("LMODE") == "MU" )  _mode = 2;

      // Set up cuts
      Cut cuts;
      if (_mode == 2) { // muon channel
        cuts = Cuts::pT > 25*GeV && Cuts::abseta < 2.4;;
      } else if (_mode) { // electron channel
        cuts = Cuts::pT > 25*GeV && ( Cuts::etaIn(-2.47, -1.52) || Cuts::etaIn(-1.37, 1.37) || Cuts::etaIn(1.52, 2.47) );
      } else { // combined data extrapolated to common phase space
        cuts = Cuts::pT > 25*GeV && Cuts::abseta < 2.5;
      }

      // Boson finders
      FinalState fs;
      WFinder wfinder(fs, cuts, _mode > 1? PID::MUON : PID::ELECTRON, 40*GeV, 8*TeV, 0., 0.1, 
				              WFinder::ChargedLeptons::PROMPT, WFinder::ClusterPhotons::NODECAY, 
                      WFinder::AddPhotons::NO, WFinder::MassWindow::MT);
      declare(wfinder, "WF");

      ZFinder zfinder(fs, cuts, _mode > 1? PID::MUON : PID::ELECTRON, 66*GeV, 116*GeV, 0.1, 
                      ZFinder::ChargedLeptons::PROMPT, ZFinder::ClusterPhotons::NODECAY, ZFinder::AddPhotons::NO);
      declare(zfinder, "ZF");

      // Jets
      VetoedFinalState jet_fs(fs);
      jet_fs.addVetoOnThisFinalState(getProjection<WFinder>("WF"));
      jet_fs.addVetoOnThisFinalState(getProjection<ZFinder>("ZF"));
      FastJets jets(jet_fs, FastJets::ANTIKT, 0.4, JetAlg::Muons::ALL, JetAlg::Invisibles::ALL);
      declare(jets, "Jets");


      // Book Rjets plots
      _suff = string("-y0") + to_str(_mode + 1);
      hInit("Njets_incl",  "d01"); // inclusive number of jets
      hInit("Njets_excl",  "d04"); // exclusive number of jets
      hInit("Pt1_N1incl",  "d05"); // leading jet pT, at least 1 jet
      hInit("Pt1_N1excl",  "d06"); // leading jet pT, exactly 1 jet
      hInit("Pt1_N2incl",  "d07"); // leading jet pT, at least 2 jets
      hInit("Pt1_N3incl",  "d08"); // leading jet pT, at least 3 jets
      hInit("Pt2_N2incl",  "d09"); // subleading jet pT, at least 2 jets
      hInit("Pt3_N3incl",  "d10"); // sub-subleading jet pT, at least 3 jets
      hInit("ST_N2incl",   "d11"); // scalar jet pT sum, at least 2 jets
      hInit("ST_N2excl",   "d12"); // scalar jet pT sum, exactly 2 jets
      hInit("ST_N3incl",   "d13"); // scalar jet pT sum, at least 3 jets
      hInit("ST_N3excl",   "d14"); // scalar jet pT sum, exactly 3 jets
      hInit("DR_N2incl",   "d15"); // deltaR(j1, j2), at least 2 jets
      hInit("DPhi_N2incl", "d16"); // deltaPhi(j1, j2), at least 2 jets
      hInit("Mjj_N2incl",  "d17"); // mjj, at least 2 jets
      hInit("Rap1_N1incl", "d18"); // leading jet rapidity, at least 1 jet
      hInit("Rap2_N2incl", "d19"); // subleading jet rapidity, at least 2 jets
      hInit("Rap3_N3incl", "d20"); // sub-subleading jet rapidity, at least 3 jets

      // Also book numerator and denominator for Rjets plots
      for (auto& item : _plots) {
        book(item.second.comp[0], item.second.ref + "2" + _suff, refData(item.second.ref + "1" + _suff));
        book(item.second.comp[1], item.second.ref + "3" + _suff, refData(item.second.ref + "1" + _suff));
      }
    }


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

      // Retrieve boson candidate
      const WFinder& wf = apply<WFinder>(event, "WF");
      const ZFinder& zf = apply<ZFinder>(event, "ZF");
      if (wf.empty() && zf.empty())  vetoEvent;

      // Retrieve jets
      const JetAlg& jetfs = apply<JetAlg>(event, "Jets");
      Jets jets = jetfs.jetsByPt(Cuts::pT > 30*GeV && Cuts::absrap < 4.4);

      // Apply boson cuts and fill histograms
      if (!zf.empty()) {
        const Particles& leptons = zf.constituents();
        if (oppSign(leptons[0], leptons[1]) && deltaR(leptons[0], leptons[1]) > 0.2)
          fillPlots(leptons, jets, 1);
      }
      if (!wf.empty()) {
        const Particles& leptons = wf.constituentLeptons();
        if (wf.constituentNeutrino().pT() > 25*GeV && wf.mT() > 40*GeV )
          fillPlots(leptons, jets, 0);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      ///  Normalise, scale and otherwise manipulate histograms here
      const double sf( crossSection() / sumOfWeights() );
      for (const auto& item : _plots) {
        scale(item.second.comp[0], sf);
        scale(item.second.comp[1], sf);
        divide(item.second.comp[0], item.second.comp[1], item.second.ratio);
      }
    }
    //@}


    /// Analysis helper functions
    //@{

    /// Histogram filling function, to avoid duplication
    void fillPlots(const Particles& leptons, Jets& jets, int isZ) {
      // Do jet-lepton overlap removal
      idiscardIfAnyDeltaRLess(jets, leptons, 0.5);

      // Calculate jet ST
      const size_t njets = jets.size();
      const double ST = sum(jets, pT, 0.0)/GeV;

      // Fill jet histos
      _plots["Njets_excl"].comp[isZ]->fill(njets + 0.5);
      for (size_t i = 0; i <= njets; ++i)
        _plots["Njets_incl"].comp[isZ]->fill(i + 0.5);

      if (njets > 0) {
        const double pT1  = jets[0].pT()/GeV;
        const double rap1 = jets[0].absrap();
        _plots["Pt1_N1incl" ].comp[isZ]->fill(pT1);
        _plots["Rap1_N1incl"].comp[isZ]->fill(rap1);

        if (njets == 1) {
          _plots["Pt1_N1excl"].comp[isZ]->fill(pT1);
        } else if (njets > 1) {
          const double pT2  = jets[1].pT()/GeV;
          const double rap2 = jets[1].absrap();
          const double dR   = deltaR(jets[0], jets[1]);
          const double dPhi = deltaPhi(jets[0], jets[1]);
          const double mjj  = (jets[0].momentum() + jets[1].momentum()).mass()/GeV;
          _plots["Pt1_N2incl" ].comp[isZ]->fill(pT1);
          _plots["Pt2_N2incl" ].comp[isZ]->fill(pT2);
          _plots["Rap2_N2incl"].comp[isZ]->fill(rap2);
          _plots["DR_N2incl"  ].comp[isZ]->fill(dR);
          _plots["DPhi_N2incl"].comp[isZ]->fill(dPhi);
          _plots["Mjj_N2incl" ].comp[isZ]->fill(mjj);
          _plots["ST_N2incl"  ].comp[isZ]->fill(ST);

          if (njets == 2) {
            _plots["ST_N2excl"].comp[isZ]->fill(ST);
          } else if (njets > 2) {
            const double pT3  = jets[2].pT()/GeV;
            const double rap3 = jets[2].absrap();
            _plots["Pt1_N3incl" ].comp[isZ]->fill(pT1);
            _plots["Pt3_N3incl" ].comp[isZ]->fill(pT3);
            _plots["Rap3_N3incl"].comp[isZ]->fill(rap3);
            _plots["ST_N3incl"  ].comp[isZ]->fill(ST);

            if (njets == 3)
              _plots["ST_N3excl"].comp[isZ]->fill(ST);
          }
        }
      }
    }


    /// Helper for histogram initialisation
    void hInit(string label, string ident) {
      string pre = ident + "-x0";
      _plots[label].ref = pre;
      book(_plots[label].ratio, pre + "1" + _suff, true);
    }

    //@}


  protected:

    // Data members
    size_t _mode;
    string _suff;


  private:

    /// @name Map of histograms
    map<string, Plots> _plots;

  };

  // Hooks for the plugin system
  RIVET_DECLARE_PLUGIN(ATLAS_2014_I1312627);
}

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