1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4#include "Rivet/Projections/UnstableParticles.hh"
 5#include "Rivet/Projections/Beam.hh"
 6
 7namespace Rivet {
 8
 9
10  /// @brief Add a short analysis description here
11  class HRS_1992_I339573 : public Analysis {
12  public:
13
14    /// Constructor
15    RIVET_DEFAULT_ANALYSIS_CTOR(HRS_1992_I339573);
16
17
18    /// @name Analysis methods
19    //@{
20
21    /// Book histograms and initialise projections before the run
22    void init() {
23      declare(Beam(), "Beams");
24      declare(FinalState(), "FS");
25      declare(UnstableParticles(), "UFS");
26
27      // Book histograms
28      book(_h_lambda, 1 , 1, 1);
29    }
30
31
32    /// Perform the per-event analysis
33    void analyze(const Event& event) {
34      // First, veto on leptonic events by requiring at least 4 charged FS particles
35      const FinalState& fs = apply<FinalState>(event, "FS");
36      const size_t numParticles = fs.particles().size();
37
38      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
39      if (numParticles < 2) {
40        MSG_DEBUG("Failed leptonic event cut");
41        vetoEvent;
42      }
43      MSG_DEBUG("Passed leptonic event cut");
44
45      // Get beams and average beam momentum
46      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
47      const double meanBeamMom = ( beams.first.p3().mod() +
48                                   beams.second.p3().mod() ) / 2.0;
49      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
50
51      // Final state to get particle spectra
52      for( const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::abspid==3122)) {
53	double xE = p.E()/meanBeamMom;
54	_h_lambda->fill(xE);
55      }
56
57    }
58
59
60    /// Normalise histograms etc., after the run
61    void finalize() {
62
63      double fact = sqr(sqrtS())/GeV2*crossSection()/nanobarn/sumOfWeights();
64      scale(_h_lambda, fact); 
65    }
66
67    //@}
68
69
70    /// @name Histograms
71    //@{
72    Histo1DPtr _h_lambda;
73    //@}
74
75
76  };
77
78
79  // The hook for the plugin system
80  RIVET_DECLARE_PLUGIN(HRS_1992_I339573);
81
82
83}