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CDF_1996_S3418421

Dijet angular distributions
Experiment: CDF (Tevatron Run 1)
Inspire ID: 423414
Status: VALIDATED
Authors:
  • Frank Siegert
References: Beams: p- p+
Beam energies: (900.0, 900.0) GeV
Run details:
  • QCD dijet events at Tevatron $\sqrt{s}=1.8$ TeV without MPI.

Measurement of jet angular distributions in events with two jets in the final state in 5 bins of dijet invariant mass. Based on $106 \mathrm{pb}^{-1}$

Source code: CDF_1996_S3418421.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Tools/BinnedHistogram.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/FastJets.hh"

namespace Rivet {


  /// @brief CDF dijet angular distributions
  class CDF_1996_S3418421 : public Analysis {
  public:

    /// @name Constructors etc.
    //@{

    /// Constructor
    CDF_1996_S3418421()
      : Analysis("CDF_1996_S3418421")
    {
    }

    //@}


  public:

    /// @name Analysis methods
    //@{

    /// Book histograms and initialise projections before the run
    void init() {
      FinalState fs(-4.2, 4.2);
      declare(FastJets(fs, FastJets::CDFJETCLU, 0.7), "Jets");

      _h_chi.addHistogram(241.0, 300.0, bookHisto1D(1, 1, 1));
      _h_chi.addHistogram(300.0, 400.0, bookHisto1D(1, 1, 2));
      _h_chi.addHistogram(400.0, 517.0, bookHisto1D(1, 1, 3));
      _h_chi.addHistogram(517.0, 625.0, bookHisto1D(1, 1, 4));
      _h_chi.addHistogram(625.0, 1800.0, bookHisto1D(1, 1, 5));
      _h_ratio = bookScatter2D(2, 1, 1);
      _htmp_chi_above_25 = bookHisto1D("TMP/chiabove25", refData(2, 1, 1));
      _htmp_chi_below_25 = bookHisto1D("TMP/chibelow25", refData(2, 1, 1));
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const double weight = event.weight();

      Jets jets = apply<FastJets>(event, "Jets").jetsByPt(50.0*GeV);
      if (jets.size() < 2) vetoEvent;

      const FourMomentum jet1 = jets[0].momentum();
      const FourMomentum jet2 = jets[1].momentum();
      const double eta1 = jet1.eta();
      const double eta2 = jet2.eta();
      const double chi = exp(fabs(eta1 - eta2));
      if (fabs(eta2) > 2.0 || fabs(eta1) > 2.0 || chi > 5.0) vetoEvent;

      double m = FourMomentum(jet1 + jet2).mass();
      _h_chi.fill(m, chi, weight);

      // Fill ratio numerator or denominator depending on chi value
      ((chi > 2.5) ? _htmp_chi_above_25 : _htmp_chi_below_25)->fill(m/GeV, weight);
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      foreach (Histo1DPtr hist, _h_chi.getHistograms()) {
        normalize(hist);
      }
      divide(_htmp_chi_below_25, _htmp_chi_above_25, _h_ratio);
    }

    //@}

  private:

    /// @name Histograms
    //@{
    BinnedHistogram<double> _h_chi;
    Histo1DPtr _htmp_chi_above_25, _htmp_chi_below_25;
    Scatter2DPtr _h_ratio;
    //@}

  };



  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(CDF_1996_S3418421);

}