Rivet analyses

title: CMS_2011_I912560

Measurement of ratio of the 3-jet over 2-jet cross section in $pp$ collisions at $\sqrt{s} = 7$ TeV

Experiment: CMS (LHC)

Inspire ID: 912560

Status: VALIDATED

Authors: - Tomo Umer

References: - Phys. Lett. B 702 (2011) 336

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - Inclusive QCD at 7 TeV. $\hat{\pT}$ (or equivalent) greater than 30 GeV

A measurement of the ratio of the inclusive 3-jet to 2-jet cross sections as a function of the total jet transverse momentum, $H_T$, in the range $0.2 < H_T < 2.5$ TeV is presented. The data have been collected at a proton--proton centre-of-mass energy of 7~TeV with the CMS detector at the LHC, and correspond to an integrated luminosity of 36/pb. Jets are anti-$k_t$ with $R = 0.5$, $p_\perp > 50~\GeV$ and $|\eta| < 2.5$.

Source code:CMS_2011_I912560.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// CMS ratio of 3-jet to 2-jet cross-sections class CMS_2011_I912560 : public Analysis { public:

RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2011_I912560);


void init() {
  FinalState fs;
  FastJets akt(fs, JetAlg::ANTIKT, 0.5);
  declare(akt, "antikT");

  book(_h_tmp_dijet, "TMP/dijet", refData(1, 1, 1));
  book(_h_tmp_trijet, "TMP/trijet", refData(1, 1, 1));
  book(_h_r32, 1, 1, 1);
}


void analyze(const Event& event) {

  Jets highpT_jets;
  double HT = 0;
  for (const Jet& jet : apply<JetFinder>(event, "antikT").jetsByPt(Cuts::pT > 50.0 * GeV)) {
    if (jet.abseta() < 2.5) {
      highpT_jets.push_back(jet);
      HT += jet.pT();
    }
  }
  if (highpT_jets.size() < 2) vetoEvent;
  if (highpT_jets.size() >= 2) _h_tmp_dijet->fill(HT / TeV);
  if (highpT_jets.size() >= 3) _h_tmp_trijet->fill(HT / TeV);
}


void finalize() {
  divide(_h_tmp_trijet, _h_tmp_dijet, _h_r32);
}

private:

/// @{
Histo1DPtr _h_tmp_dijet, _h_tmp_trijet;
Estimate1DPtr _h_r32;
/// @}

};

RIVET_DECLARE_ALIASED_PLUGIN(CMS_2011_I912560, CMS_2011_S9088458);

} ```

Aliases: - CMS_2011_S9088458