Rivet analyses

title: ATLAS_2016_I1479760

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 $(37.3 \pm 1.3)$ $\mathrm{pb}^{-1}$, 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 $p_{\mathrm{T}} \geq 20$ GeV and $\eta \leq 4.4$, and at least one of which has $p_{\text{T}} \geq 42.5$ GeV.

Source code:ATLAS_2016_I1479760.cc

```c++ // -- 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);

} ```