1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4#include "Rivet/Projections/Beam.hh"
 5#include "Rivet/Projections/ChargedFinalState.hh"
 6#include "Rivet/Projections/UnstableParticles.hh"
 7
 8namespace Rivet {
 9
10
11  /// @brief L3 inclusive eta production in hadronic Z0 decays
12  /// @author Simone Amoroso
13  class L3_1992_I336180 : public Analysis {
14  public:
15
16    /// Constructor
17    RIVET_DEFAULT_ANALYSIS_CTOR(L3_1992_I336180);
18
19
20    /// @name Analysis methods
21    /// @{
22
23    /// Book histograms and initialise projections before the run
24    void init() {
25
26      // Initialise and register projections
27      declare(Beam(), "Beams");
28      declare(ChargedFinalState(), "FS");
29      declare(UnstableParticles(), "UFS");
30
31      // Book histograms
32      book(_histXpEta , 1, 1, 1);
33      book(_histLnXpEta , 2, 1, 1);
34
35    }
36
37
38    /// Perform the per-event analysis
39    void analyze(const Event& event) {
40
41      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
42      const FinalState& fs = apply<FinalState>(event, "FS");
43      if (fs.particles().size() < 2) {
44	MSG_DEBUG("Failed ncharged cut");
45	vetoEvent;
46      }
47      MSG_DEBUG("Passed ncharged cut");
48
49      // Get beams and average beam momentum
50      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
51      const double meanBeamMom = ( beams.first.p3().mod() + beams.second.p3().mod() ) / 2.0;
52      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
53
54      // Final state of unstable particles to get particle spectra
55      const Particles& etas = apply<UnstableParticles>(event, "UFS").particles(Cuts::abspid==PID::ETA);
56
57      for (const Particle& p : etas) {
58	double xp = p.p3().mod()/meanBeamMom;
59        MSG_DEBUG("Eta xp = " << xp);
60        _histXpEta->fill(xp);
61        _histLnXpEta->fill(log(1./xp));
62      }
63    }
64
65    /// Normalise histograms etc., after the run
66    void finalize() {
67      scale(_histXpEta, 1./sumOfWeights());
68      scale(_histLnXpEta, 1./sumOfWeights());
69    }
70
71    /// @}
72
73
74  private:
75
76    Histo1DPtr _histXpEta;
77    Histo1DPtr _histLnXpEta;
78
79  };
80
81
82
83  RIVET_DECLARE_PLUGIN(L3_1992_I336180);
84
85
86}