// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/FastJets.hh"

namespace Rivet {


  /// @brief CDF dijet cross-section, differential in dijet mass
  class CDF_2000_I511377 : public Analysis {
  public:

    RIVET_DEFAULT_ANALYSIS_CTOR(CDF_2000_I511377);


    /// @name Analysis methods
    /// @{

    /// Book histograms and initialise projections before the run
    void init() {
      FinalState fs((Cuts::etaIn(-4.2, 4.2)));
      declare(FastJets(fs, JetAlg::CDFJETCLU, 0.7), "Jets");
      book(_h_mjj ,1, 1, 1);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      Jets jets = apply<FastJets>(event, "Jets").jets(cmpMomByEt);
      if (jets.size() < 2) vetoEvent;
      FourMomentum jet1 = jets[0].momentum();
      FourMomentum jet2 = jets[1].momentum();
      double eta1 = jet1.eta();
      double eta2 = jet2.eta();
      if (fabs(eta1) > 2.0 || fabs(eta2) > 2.0) vetoEvent;
      if (fabs(tanh((eta1-eta2)/2)) > 2.0/3.0) vetoEvent;
      double mjj = FourMomentum(jet1+jet2).mass()/GeV;
      if (mjj < 180) vetoEvent;
      _h_mjj->fill(mjj);
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_h_mjj, crossSection()/picobarn/sumOfWeights());
    }

    /// @}


  private:

    /// Histogram
    Histo1DPtr _h_mjj;

  };



  RIVET_DECLARE_ALIASED_PLUGIN(CDF_2000_I511377, CDF_2000_S4266730);

}
