1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4#include "Rivet/Projections/ChargedFinalState.hh"
 5#include "Rivet/Projections/UnstableParticles.hh"
 6#include "Rivet/Projections/Beam.hh"
 7
 8namespace Rivet {
 9
10
11  /// @brief A Measurement of K*+- (892) production in hadronic Z0 decays
12  /// @author Simone Amoroso
13  class OPAL_1993_I342766 : public Analysis {
14  public:
15
16    /// Constructor
17    RIVET_DEFAULT_ANALYSIS_CTOR(OPAL_1993_I342766);
18
19
20    /// @name Analysis methods
21    //@{
22
23    /// Book histograms and initialise projections before the run
24    void init() {
25      // Initialise and register projections
26      declare(Beam(), "Beams");
27      declare(ChargedFinalState(), "FS");
28      declare(UnstableParticles(), "UFS");
29      // Book histograms
30      book(_histXeKStar892   , 1, 1, 1);
31      book(_histMeanKStar892   , 2, 1, 1);
32    }
33
34
35    /// Perform the per-event analysis
36    void analyze(const Event& event) {
37
38      const FinalState& fs = apply<FinalState>(event, "FS");
39      const size_t numParticles = fs.particles().size();
40
41      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
42      if (numParticles < 2) {
43	MSG_DEBUG("Failed leptonic event cut");
44	vetoEvent;
45      }
46      MSG_DEBUG("Passed leptonic event cut");
47
48      // Get beams and average beam momentum
49      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
50      const double meanBeamMom = ( beams.first.p3().mod() +
51				   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 UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
56
57      for (const Particle& p : ufs.particles(Cuts::abspid==323)) {
58        double xp = p.p3().mod()/meanBeamMom;
59        _histXeKStar892->fill(xp);
60        _histMeanKStar892->fill(_histMeanKStar892->bin(0).xMid());
61      }
62    }
63
64
65    /// Normalise histograms etc., after the run
66    void finalize() {
67      scale(_histXeKStar892, 1./sumOfWeights());
68      scale(_histMeanKStar892, 1./sumOfWeights());
69    }
70
71    //@}
72
73
74  private:
75
76    /// @name Histograms
77    Histo1DPtr _histXeKStar892;
78    Histo1DPtr _histMeanKStar892;
79
80  };
81
82
83
84  // The hook for the plugin system
85  RIVET_DECLARE_PLUGIN(OPAL_1993_I342766);
86
87
88}