DELPHI_1995_S3137023.cc

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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/RivetAIDA.hh"
#include "Rivet/Tools/ParticleIdUtils.hh"
#include "Rivet/Projections/Beam.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/UnstableFinalState.hh"

namespace Rivet {


  /// @brief DELPHI strange baryon paper
  /// @author Hendrik Hoeth
  class DELPHI_1995_S3137023 : public Analysis {
  public:

    /// Constructor
    DELPHI_1995_S3137023()
      : Analysis("DELPHI_1995_S3137023")
    {
      setBeams(ELECTRON, POSITRON);
      _weightedTotalNumXiMinus = 0;
      _weightedTotalNumSigma1385Plus = 0;
    }

 
    /// @name Analysis methods
    //@{

    void init() {
      addProjection(Beam(), "Beams");
      addProjection(ChargedFinalState(), "FS");
      addProjection(UnstableFinalState(), "UFS");

      _histXpXiMinus       = bookHistogram1D(2, 1, 1);
      _histXpSigma1385Plus = bookHistogram1D(3, 1, 1);
    }


    void analyze(const Event& e) {
      // First, veto on leptonic events by requiring at least 4 charged FS particles
      const FinalState& fs = applyProjection<FinalState>(e, "FS");
      const size_t numParticles = fs.particles().size();
   
      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
      if (numParticles < 2) {
        getLog() << Log::DEBUG << "Failed leptonic event cut" << endl;
        vetoEvent;
      }
      getLog() << Log::DEBUG << "Passed leptonic event cut" << endl;
   
      // Get event weight for histo filling
      const double weight = e.weight();
   
      // Get beams and average beam momentum
      const ParticlePair& beams = applyProjection<Beam>(e, "Beams").beams();
      const double meanBeamMom = ( beams.first.momentum().vector3().mod() +
                                   beams.second.momentum().vector3().mod() ) / 2.0;
      getLog() << Log::DEBUG << "Avg beam momentum = " << meanBeamMom << endl;
   
      // Final state of unstable particles to get particle spectra
      const UnstableFinalState& ufs = applyProjection<UnstableFinalState>(e, "UFS");
   
      foreach (const Particle& p, ufs.particles()) {
        const int id = abs(p.pdgId());
        switch (id) {
        case 3312:
          _histXpXiMinus->fill(p.momentum().vector3().mod()/meanBeamMom, weight);
          _weightedTotalNumXiMinus += weight;
          break;
        case 3114:
          _histXpSigma1385Plus->fill(p.momentum().vector3().mod()/meanBeamMom, weight);
          _weightedTotalNumSigma1385Plus += weight;
          break;
        }
      }
   
    }
     

    /// Finalize
    void finalize() {
      normalize(_histXpXiMinus       , _weightedTotalNumXiMinus/sumOfWeights());
      normalize(_histXpSigma1385Plus , _weightedTotalNumSigma1385Plus/sumOfWeights());
    }
 
    //@}


  private:
 
    /// Store the weighted sums of numbers of charged / charged+neutral
    /// particles - used to calculate average number of particles for the
    /// inclusive single particle distributions' normalisations.
    double _weightedTotalNumXiMinus;
    double _weightedTotalNumSigma1385Plus;
 
    AIDA::IHistogram1D *_histXpXiMinus;
    AIDA::IHistogram1D *_histXpSigma1385Plus;
    //@}
 
  };



  // This global object acts as a hook for the plugin system
  AnalysisBuilder<DELPHI_1995_S3137023> plugin_DELPHI_1995_S3137023;

}