Rivet analyses

title: D0_2011_I895662

3-jet invariant mass

Experiment: D0 (Tevatron Run 2)

Inspire ID: 895662

Status: VALIDATED

Authors: - Hendrik Hoeth

References: - arxiv:1104.1986

Beams: p- p+

Beam energies: (980.0, 980.0)GeV

Run details: - QCD events, three jets above 40 GeV.

Inclusive three-jet differential cross-section as a function of invariant mass of the three jets with the largest transverse momenta. The measurement is made in three rapidity regions ($|y|<0.8, 1.6, 2.4$) and with jets above 40, 70, and 100 GeV.

Source code:D0_2011_I895662.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

class D0_2011_I895662 : public Analysis { public:

RIVET_DEFAULT_ANALYSIS_CTOR(D0_2011_I895662);

public:

void init() {
  FastJets jets(FinalState((Cuts::etaIn(-3.6, 3.6))), JetAlg::D0ILCONE, 0.7);
  jets.useInvisibles();
  declare(jets, "Jets");

  book(_h_m3j_08_40, 1, 1, 1);
  book(_h_m3j_16_40, 2, 1, 1);
  book(_h_m3j_24_40, 3, 1, 1);
  book(_h_m3j_24_70, 4, 1, 1);
  book(_h_m3j_24_100, 5, 1, 1);
}


void analyze(const Event& event) {
  Jets jets = apply<FastJets>(event, "Jets").jetsByPt(Cuts::pT > 40 * GeV);

  // Need three jets, leading jet above 150 GeV
  if (jets.size() < 3 || jets[0].pT() <= 150. * GeV) vetoEvent;

  std::vector<FourMomentum> p;
  for (size_t i = 0; i < 3; i++) {
    p.push_back(jets[i].momentum());
  }

  // Jets need to be separated by 2*Rcone
  if (deltaR(p[0], p[1], RAPIDITY) < 1.4 || deltaR(p[0], p[2], RAPIDITY) < 1.4
      || deltaR(p[1], p[2], RAPIDITY) < 1.4)
    vetoEvent;

  // Leading three jets need to be within |y|<2.4
  double ymax = fabs(p[0].rapidity());
  for (size_t i = 1; i < 3; i++) {
    if (ymax < fabs(p[i].rapidity())) ymax = fabs(p[i].rapidity());
  }
  if (ymax >= 2.4) vetoEvent;

  double m3jet = (p[0] + p[1] + p[2]).mass() / GeV;

  if (ymax < 0.8) _h_m3j_08_40->fill(m3jet);
  if (ymax < 1.6) _h_m3j_16_40->fill(m3jet);
  if (ymax < 2.4) {
    _h_m3j_24_40->fill(m3jet);
    if (p[2].pT() > 70. * GeV) _h_m3j_24_70->fill(m3jet);
    if (p[2].pT() > 100. * GeV) _h_m3j_24_100->fill(m3jet);
  }
}


void finalize() {
  // Factor of 1000 is based on GeV <-> TeV mismatch between paper and Hepdata table
  scale(_h_m3j_08_40, 1000 * crossSection() / picobarn / sumOfWeights());
  scale(_h_m3j_16_40, 1000 * crossSection() / picobarn / sumOfWeights());
  scale(_h_m3j_24_40, 1000 * crossSection() / picobarn / sumOfWeights());
  scale(_h_m3j_24_70, 1000 * crossSection() / picobarn / sumOfWeights());
  scale(_h_m3j_24_100, 1000 * crossSection() / picobarn / sumOfWeights());
}

private:

Histo1DPtr _h_m3j_08_40;
Histo1DPtr _h_m3j_16_40;
Histo1DPtr _h_m3j_24_40;
Histo1DPtr _h_m3j_24_70;
Histo1DPtr _h_m3j_24_100;

};

RIVET_DECLARE_PLUGIN(D0_2011_I895662);

} ```