1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/Beam.hh"
  4#include "Rivet/Projections/ChargedFinalState.hh"
  5#include "Rivet/Projections/TriggerCDFRun0Run1.hh"
  6
  7namespace Rivet {
  8
  9
 10  /// @brief CDF Run I charged multiplicity measurement
 11  ///
 12  /// @author Hendrik Hoeth
 13  ///
 14  /// This analysis measures the charged multiplicity distribution
 15  /// in minimum bias events at two different center-of-mass energies:
 16  /// \f$ \sqrt{s} = \f$ 630 and 1800 GeV.
 17  ///
 18  /// Particles with c*tau > 10 mm are considered stable, i.e. they
 19  /// are reconstructed and their decay products removed. Selection
 20  /// cuts are |eta|<1 and pT>0.4 GeV.
 21  ///
 22  /// @par Run conditions
 23  ///
 24  /// @arg Two different beam energies: \f$ \sqrt{s} = \$f 630 & 1800 GeV
 25  /// @arg Run with generic QCD events.
 26  /// @arg Set particles with c*tau > 10 mm stable
 27  class CDF_2002_I567774 : public Analysis {
 28  public:
 29
 30    RIVET_DEFAULT_ANALYSIS_CTOR(CDF_2002_I567774);
 31
 32
 33    /// @name Analysis methods
 34    /// @{
 35
 36    /// Book projections and histograms
 37    void init() {
 38      declare(TriggerCDFRun0Run1(), "Trigger");
 39      const ChargedFinalState cfs(Cuts::abseta < 1.0 && Cuts::pT >= 0.4*GeV);
 40      declare(cfs, "FS");
 41
 42      // Histos
 43      if (isCompatibleWithSqrtS(630*GeV)) {
 44        book(_hist_multiplicity  ,1, 1, 1);
 45        book(_hist_pt_vs_multiplicity  ,3, 1, 1);
 46      } else if (isCompatibleWithSqrtS(1800*GeV)) {
 47        book(_hist_multiplicity ,2, 1, 1);
 48        book(_hist_pt_vs_multiplicity ,4, 1, 1);
 49      }
 50      book(_sumWTrig, "sumWTrig");
 51
 52    }
 53
 54
 55    /// Do the analysis
 56    void analyze(const Event& evt) {
 57      // Trigger
 58      const bool trigger = apply<TriggerCDFRun0Run1>(evt, "Trigger").minBiasDecision();
 59      if (!trigger) vetoEvent;
 60      _sumWTrig->fill();
 61
 62      // Get beam energy and tracks
 63      const ChargedFinalState& fs = apply<ChargedFinalState>(evt, "FS");
 64      const size_t numParticles = fs.particles().size();
 65
 66      // Fill histos of charged multiplicity distributions
 67      _hist_multiplicity->fill(numParticles);
 68
 69      // Fill histos for <pT> vs. charged multiplicity
 70      for (const Particle& p : fs.particles()) {
 71        const double pT = p.pT();
 72        _hist_pt_vs_multiplicity->fill(numParticles, pT/GeV);
 73      }
 74
 75    }
 76
 77
 78    void finalize() {
 79      // This normalisation is NOT a cross-section.
 80      // In the paper the x-axes (!) of the histograms are
 81      // scaled such that they can put both energies in the
 82      // same plot. Of course this affects the area, too.
 83      // Since we want to plot the actual multiplicity, we
 84      // scale the x-axes back and have to adjust the areas
 85      // accordingly. The scale factors are given in the
 86      // legend of the plot in the paper. Have a look at
 87      // figure 1 and everything immediately becomes clear.
 88      // DON'T TRY TO REPAIR THIS, YOU WILL BREAK IT.
 89      if (isCompatibleWithSqrtS(630*GeV)) {
 90        normalize(_hist_multiplicity, 3.21167); // fixed norm OK
 91      } else if (isCompatibleWithSqrtS(1800*GeV)) {
 92        normalize(_hist_multiplicity, 4.19121); // fixed norm OK
 93      }
 94    }
 95
 96    /// @}
 97
 98
 99  private:
100
101    /// Counter
102    CounterPtr _sumWTrig;
103
104    /// @name Histos
105    /// @{
106    Histo1DPtr _hist_multiplicity;
107    Profile1DPtr _hist_pt_vs_multiplicity;
108    /// @}
109
110  };
111
112
113
114  RIVET_DECLARE_ALIASED_PLUGIN(CDF_2002_I567774, CDF_2002_S4796047);
115
116}