1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/Beam.hh"
 4#include "Rivet/Projections/ChargedFinalState.hh"
 5#include "Rivet/Projections/UnstableParticles.hh"
 6
 7namespace Rivet {
 8
 9
10  /// @brief OPAL strange baryon paper
11  /// @author Peter Richardson
12  class OPAL_1997_I421977 : public Analysis {
13  public:
14
15    /// Constructor
16    RIVET_DEFAULT_ANALYSIS_CTOR(OPAL_1997_I421977);
17
18
19    /// @name Analysis methods
20    /// @{
21
22    /// Book histograms and initialise projections before the run
23    void init() {
24      declare(Beam(), "Beams");
25      declare(ChargedFinalState(), "FS");
26      declare(UnstableParticles(), "UFS");
27
28      // Book histograms
29      book(_h_plus,  1, 1, 1);
30      book(_h_minus, 2, 1, 1);
31    }
32
33
34    /// Perform the per-event analysis
35    void analyze(const Event& event) {
36      // First, veto on leptonic events by requiring at least 4 charged FS particles
37      const FinalState& fs = apply<FinalState>(event, "FS");
38      const size_t numParticles = fs.particles().size();
39
40      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
41      if (numParticles < 2) {
42        MSG_DEBUG("Failed leptonic event cut");
43        vetoEvent;
44      }
45      MSG_DEBUG("Passed leptonic event cut");
46
47      // Get beams and average beam momentum
48      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
49      const double meanBeamMom = ( beams.first.p3().mod() +
50                                   beams.second.p3().mod() ) / 2.0;
51      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
52
53      // Final state of unstable particles to get particle spectra
54      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
55
56      for (const Particle& p : ufs.particles()) {
57        const int id = p.abspid();
58        double xE = p.E()/meanBeamMom;
59        if(id==3222)      _h_plus ->fill(xE);
60        else if(id==3112) _h_minus->fill(xE);
61      }
62    }
63
64
65    /// Normalise histograms etc., after the run
66    void finalize() {
67
68      double fact=1./sumOfWeights();
69      scale(_h_plus , fact);
70      scale(_h_minus, fact);
71
72    }
73
74    /// @}
75
76
77    /// @name Histograms
78    /// @{
79      Histo1DPtr _h_plus,_h_minus;
80    /// @}
81
82
83  };
84
85
86  RIVET_DECLARE_PLUGIN(OPAL_1997_I421977);
87
88
89}