Rivet analyses

Charge multiplicity for different jet multiplicities in hadronic Z0 decays

Experiment: DELPHI (LEP)

Inspire ID: 334948

Status: VALIDATED

Authors: - Peter Richardson

References: - Z.Phys. C56 (1992) 63-76, 1992

Beams: e+ e-

Beam energies: (45.6, 45.6)GeV

Run details: - $\sqrt{s} = 91.2$ GeV, e+e−− > Z0 production with hadronic decays only

The charged multiplicity distribution in hadron Z0 decays for different numbers of final state jets.

Source code:DELPHI_1992_I334948.cc

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

namespace Rivet {


  /// @brief Charged multiplicity for different numbers of final state jets
  class DELPHI_1992_I334948 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(DELPHI_1992_I334948);


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

    /// Book histograms and initialise projections before the run
    void init() {

      // Initialise and register projections
      const ChargedFinalState cfs;
      declare(cfs, "FS");
      declare(FastJets(cfs, JetAlg::JADE), "Jets");

      // Book histograms
      for (unsigned int ih=0; ih<3; ++ih) {
        for (unsigned int iy=0; iy<3; ++iy) {
          book(_h_mult[ih][iy], ih+1, 1, iy+1);
        }
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const FinalState& fs = apply<FinalState>(event, "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) {
        MSG_DEBUG("Failed leptonic event cut");
        vetoEvent;
      }
      MSG_DEBUG("Passed leptonic event cut");
      const FastJets& jets = apply<FastJets>(event, "Jets");
      if (jets.clusterSeq()) {
        vector<double> ycut = {0.01,0.02,0.04};
        for (unsigned int ih=0;ih<3;++ih) {
          int nbin = jets.clusterSeq()->n_exclusive_jets_ycut(ycut[ih])-2;
          if (nbin<0 || nbin>2) continue;
          _h_mult[ih][nbin]->fill(numParticles);
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {

      for (unsigned int ih=0; ih<3; ++ih) {
        for (unsigned int iy=0; iy<3; ++iy) {
          normalize(_h_mult[ih][iy], 1000.);
        }
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    BinnedHistoPtr<int> _h_mult[3][3];
    /// @}


  };


  RIVET_DECLARE_PLUGIN(DELPHI_1992_I334948);


}