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CMS_2015_I1327224

Search for contact interactions \& extra dimensions using dijet angular distributions in proton-proton collisions at $\sqrt{s} = 8$ TeV
Experiment: CMS (LHC)
Inspire ID: 1327224
Status: VALIDATED
Authors:
  • A. Hinzmann
No references listed
Beams: p+ p+
Beam energies: (4000.0, 4000.0) GeV
Run details:
  • Hard QCD process with a pT cut of 200 GeV on sub-leading jet is recommended.

A search is presented for quark contact interactions and extra spatial dimensions in proton-proton collisions at sqrt(s) = 8 TeV using dijet angular distributions. The search is based on a data set corresponding to an integrated luminosity of 19.7 fb-1 collected by the CMS detector at the CERN LHC. Dijet angular distributions are found to be in agreement with the perturbative QCD predictions that include electroweak corrections. Limits on the contact interaction scale from a variety of models at next-to-leading order in QCD corrections are obtained. A benchmark model in which only left-handed quarks participate is excluded up to a scale of 9.0 (11.7) TeV for destructive (constructive) interference at 95% confidence level. Lower limits between 6.0 and 8.4 TeV on the scale of virtual graviton exchange are extracted for the Arkani-Hamed--Dimopoulos--Dvali model of extra spatial dimensions.

Source code: CMS_2015_I1327224.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Tools/BinnedHistogram.hh"

namespace Rivet {


  class CMS_2015_I1327224 : public Analysis {
  public:

    DEFAULT_RIVET_ANALYSIS_CTOR(CMS_2015_I1327224);


    void init() {
      FinalState fs;
      FastJets antikt(fs, FastJets::ANTIKT, 0.5);
      declare(antikt, "ANTIKT");
      _h_chi_dijet.addHistogram(4200., 8000., bookHisto1D(1, 1, 1));
      _h_chi_dijet.addHistogram(3600., 4200., bookHisto1D(2, 1, 1));
      _h_chi_dijet.addHistogram(3000., 3600., bookHisto1D(3, 1, 1));
      _h_chi_dijet.addHistogram(2400., 3000., bookHisto1D(4, 1, 1));
      _h_chi_dijet.addHistogram(1900., 2400., bookHisto1D(5, 1, 1));
    }


    void analyze(const Event& event) {
      const double weight = event.weight();
      const Jets& jets = apply<JetAlg>(event, "ANTIKT").jetsByPt();
      if (jets.size() < 2) vetoEvent;

      FourMomentum j0(jets[0].momentum());
      FourMomentum j1(jets[1].momentum());
      double y0 = j0.rapidity();
      double y1 = j1.rapidity();
      if (fabs(y0 + y1) / 2. > 1.11) vetoEvent;

      double mjj = FourMomentum(j0 + j1).mass();
      if (mjj/GeV <1900) vetoEvent;

      double chi = exp(fabs(y0 - y1));
      if (chi >= 16.) vetoEvent;

      // Fill the histogram
      _h_chi_dijet.fill(mjj/GeV, chi, weight);
    }

    void finalize() {
      foreach (Histo1DPtr hist, _h_chi_dijet.getHistograms()) {
        normalize(hist);
      }
    }

  private:
    BinnedHistogram<double> _h_chi_dijet;
  };

  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(CMS_2015_I1327224);
}