Rivet analyses

Hard double-parton scattering in four-jet events at 7 TeV

Experiment: ATLAS (LHC)

Inspire ID: 1479760

Status: VALIDATED

Authors: - Orel Gueta - Christian Gutschow

References: - Expt page: ATLAS-STDM-2015-08 - arXiv: 1608.01857

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - Four-jet events at 7 TeV

Inclusive four-jet events produced in pp collisions at a centre-of-mass energy of $\sqrt{s} = 7$ TeV have been analysed for the presence of hard double-parton scattering using data corresponding to an integrated luminosity of (37.3 ± 1.3) pb⁻¹, collected with the ATLAS detector at the LHC. The distributions of observables sensitive to the contribution of hard double-parton scattering are provided for events containing at least four jets with p_T ≥ 20 GeV and η ≤ 4.4, and at least one of which has p_T ≥ 42.5 GeV.

Source code:`ATLAS_2016_I1479760.cc`

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

namespace Rivet {


  /// Hard double-parton scattering in four-jet events at 7 TeV
  class ATLAS_2016_I1479760 : public Analysis {
  public:


    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2016_I1479760);


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

      /// Declare AntiKt 0.6 jets without muons and neutrinos
      FastJets fastJets(FinalState(), JetAlg::ANTIKT, 0.6);
      fastJets.useInvisibles(JetInvisibles::NONE);
      fastJets.useMuons(JetMuons::NONE);
      declare(fastJets, "AntiKt6Jets");

      book(_hists["deltaPt34"], 1, 1, 1);
      book(_hists["deltaPhi34"], 2, 1, 1);
      book(_hists["deltaPt12"], 3, 1, 1);
      book(_hists["deltaPt13"], 4, 1, 1);
      book(_hists["deltaPt23"], 5, 1, 1);
      book(_hists["deltaPt14"], 6, 1, 1);
      book(_hists["deltaPt24"], 7, 1, 1);
      book(_hists["deltaPhi12"], 8, 1, 1);
      book(_hists["deltaPhi13"], 9, 1, 1);
      book(_hists["deltaPhi23"], 10, 1, 1);
      book(_hists["deltaPhi14"], 11, 1, 1);
      book(_hists["deltaPhi24"], 12, 1, 1);
      book(_hists["deltaY12"], 13, 1, 1);
      book(_hists["deltaY34"], 14, 1, 1);
      book(_hists["deltaY13"], 15, 1, 1);
      book(_hists["deltaY23"], 16, 1, 1);
      book(_hists["deltaY14"], 17, 1, 1);
      book(_hists["deltaY24"], 18, 1, 1);
      book(_hists["deltaPhiPlanes12"], 19, 1, 1);
      book(_hists["deltaPhiPlanes13"], 20, 1, 1);
      book(_hists["deltaPhiPlanes14"], 21, 1, 1);
    }


    /// Calculate the DeltaPt variable
    double calcDeltaPt(const Jet& j1, const Jet& j2) {
      return (j1.momentum() + j2.momentum()).pT() / (j1.pT() + j2.pT());
    }

    /// Calculate the DeltaPhi variable between event planes
    double calcDeltaPhiPlanes(const Jet& j1, const Jet& j2, const Jet& j3, const Jet& j4) {
      const FourMomentum sumVec1 = j1.momentum() + j2.momentum();
      const FourMomentum sumVec2 = j3.momentum() + j4.momentum();
      return deltaPhi(sumVec1, sumVec2);
    }


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

      // Retrieve all anti-kt R=0.6 jets with pT above 20 GeV and eta < 4.4
      const Jets jets = apply<JetFinder>(event, "AntiKt6Jets")
                            .jetsByPt(Cuts::pT >= 20 * GeV && Cuts::abseta <= 4.4);

      // Require at least 4 jets, with the leading jet pT above 42.5 GeV
      if (jets.size() < 4) vetoEvent;
      if (jets[0].pT() < 42.5 * GeV) vetoEvent;

      /// Fill histograms
      _hists["deltaPt12"]->fill(calcDeltaPt(jets[0], jets[1]));
      _hists["deltaPt34"]->fill(calcDeltaPt(jets[2], jets[3]));
      _hists["deltaPt13"]->fill(calcDeltaPt(jets[0], jets[2]));
      _hists["deltaPt23"]->fill(calcDeltaPt(jets[1], jets[2]));
      _hists["deltaPt14"]->fill(calcDeltaPt(jets[0], jets[3]));
      _hists["deltaPt24"]->fill(calcDeltaPt(jets[1], jets[3]));
      //
      _hists["deltaPhi12"]->fill(deltaPhi(jets[0], jets[1]));
      _hists["deltaPhi34"]->fill(deltaPhi(jets[2], jets[3]));
      _hists["deltaPhi13"]->fill(deltaPhi(jets[0], jets[2]));
      _hists["deltaPhi23"]->fill(deltaPhi(jets[1], jets[2]));
      _hists["deltaPhi14"]->fill(deltaPhi(jets[0], jets[3]));
      _hists["deltaPhi24"]->fill(deltaPhi(jets[1], jets[3]));
      //
      _hists["deltaY12"]->fill(deltaRap(jets[0], jets[1]));
      _hists["deltaY34"]->fill(deltaRap(jets[2], jets[3]));
      _hists["deltaY13"]->fill(deltaRap(jets[0], jets[2]));
      _hists["deltaY23"]->fill(deltaRap(jets[1], jets[2]));
      _hists["deltaY14"]->fill(deltaRap(jets[0], jets[3]));
      _hists["deltaY24"]->fill(deltaRap(jets[1], jets[3]));
      //
      _hists["deltaPhiPlanes12"]->fill(calcDeltaPhiPlanes(jets[0], jets[1], jets[2], jets[3]));
      _hists["deltaPhiPlanes13"]->fill(calcDeltaPhiPlanes(jets[0], jets[2], jets[1], jets[3]));
      _hists["deltaPhiPlanes14"]->fill(calcDeltaPhiPlanes(jets[0], jets[3], jets[1], jets[2]));
    }


    /// Post-run processing
    void finalize() {
      normalize(_hists);
    }

    /// Histograms
    map<string, Histo1DPtr> _hists;
  };


  RIVET_DECLARE_PLUGIN(ATLAS_2016_I1479760);

}

Rivet analyses

Hard double-parton scattering in four-jet events at 7 TeV

Source code:ATLAS_2016_I1479760.cc

Source code:`ATLAS_2016_I1479760.cc`