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CMS_2011_S9215166

Forward energy flow in MB and dijet events at 0.9 and 7 TeV
Experiment: CMS (LHC)
Inspire ID: 930319
Status: VALIDATED
Authors:
  • S. Dooling
  • A. Knutsson
References: Beams: p+ p+
Beam energies: (450.0, 450.0); (3500.0, 3500.0) GeV
Run details:
  • $pp$ MB and QCD interactions at 0.9 and 7 TeV. No pT-cuts.

Forward energy flow measured by CMS at $\sqrt{s} = 0.9$ and 7 TeV in MB and dijet events.

Source code: CMS_2011_S9215166.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/VetoedFinalState.hh"

namespace Rivet {


  class CMS_2011_S9215166 : public Analysis {
  public:

    /// Constructor
    CMS_2011_S9215166() : Analysis("CMS_2011_S9215166"), _weightMB(0.), _weightDiJet(0.) {  }


    void init() {
      const FinalState fs(-6.0, 6.0, 0.0*GeV);
      declare(fs, "FS");
      declare(FastJets(fs, FastJets::ANTIKT, 0.5), "Jets");

      VetoedFinalState fsv(fs);
      fsv.vetoNeutrinos();
      fsv.addVetoPairDetail(PID::MUON, 0.0*GeV, 99999.9*GeV);
      declare(fsv, "fsv");

      // For the MB ND selection
      const ChargedFinalState fschrgd(-6.0,6.0,0.0*GeV);
      declare(fschrgd, "fschrgd");
      VetoedFinalState fschrgdv(fschrgd);
      fschrgdv.vetoNeutrinos();
      declare(fschrgdv, "fschrgdv");

      if (fuzzyEquals(sqrtS()/GeV, 900, 1E-3)) {
        _hist_mb      = bookHisto1D(1, 1, 1); // energy flow in MB, 0.9 TeV
        _hist_dijet = bookHisto1D(2, 1, 1); // energy flow in dijet events, 0.9 TeV
      } else if (fuzzyEquals(sqrtS()/GeV, 7000, 1E-3)) {
        _hist_mb      = bookHisto1D(3, 1, 1); // energy flow in MB, 7 TeV
        _hist_dijet = bookHisto1D(4, 1, 1); // energy flow in dijet events, 7 TeV
      }
    }


    void analyze(const Event& event) {
      const double weight = event.weight();

      // Skip if the event is empty
      const FinalState& fsv = apply<FinalState>(event, "fsv");
      if (fsv.empty()) vetoEvent;

      // Veto diffractive topologies according to defined hadron level
      double count_chrg_forward = 0;
      double count_chrg_backward = 0;
      const FinalState& fschrgdv = apply<FinalState>(event, "fschrgdv");
      foreach (const Particle& p, fschrgdv.particles()) {
        if (3.9 < p.eta() && p.eta() < 4.4) count_chrg_forward++;
        if (-4.4 < p.eta() && p.eta() < -3.9) count_chrg_backward++;
      }
      if (count_chrg_forward == 0 || count_chrg_backward == 0) vetoEvent;
      /// @todo "Diffractive" veto should really also veto dijet events?


      // MINIMUM BIAS EVENTS
      _weightMB += weight;
      foreach (const Particle& p, fsv.particles()) {
        _hist_mb->fill(p.abseta(), weight*p.E()/GeV);
      }


      // DIJET EVENTS
      double PTCUT = -1.0;
      if (fuzzyEquals(sqrtS()/GeV, 900, 1E-3)) PTCUT = 8.0*GeV;
      else if (fuzzyEquals(sqrtS()/GeV, 7000, 1E-3)) PTCUT = 20.0*GeV;
      const FastJets& jetpro = apply<FastJets>(event, "Jets");
      const Jets jets = jetpro.jetsByPt(PTCUT);
      if (jets.size() >= 2) {
        // eta cut for the central jets
        if (fabs(jets[0].eta()) < 2.5 && fabs(jets[1].eta()) < 2.5) {
          // Back to back condition of the jets
          const double diffphi = deltaPhi(jets[1].phi(), jets[0].phi());
          if (diffphi-PI < 1.0) {
	    _weightDiJet += weight;
            foreach (const Particle& p, fsv.particles()) {
              _hist_dijet->fill(p.abseta(), weight*p.E()/GeV);
            }
          }
        }
      }

    }


    void finalize() {
      scale(_hist_mb   , 0.5/_weightMB   );
      scale(_hist_dijet, 0.5/_weightDiJet);
    }


  private:

    Histo1DPtr _hist_mb, _hist_dijet;
    double _weightMB,_weightDiJet;

  };


  // Hook for the plugin system
  DECLARE_RIVET_PLUGIN(CMS_2011_S9215166);

}