1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/Beam.hh"
 4#include "Rivet/Projections/FinalState.hh"
 5#include "Rivet/Projections/ChargedFinalState.hh"
 6#include "Rivet/Projections/UnstableParticles.hh"
 7
 8namespace Rivet {
 9
10
11  /// @brief pi0 and gamma spectra at 29 GeV
12  class TPC_1985_I205868 : public Analysis {
13  public:
14
15    /// Constructor
16    RIVET_DEFAULT_ANALYSIS_CTOR(TPC_1985_I205868);
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      book(_histPhoton, 1, 1, 1);
28      book(_histPi    , 2, 1, 1);
29    }
30
31
32    /// Perform the per-event analysis
33    void analyze(const Event& event) {
34
35      // First, veto on leptonic events by requiring at least 4 charged FS particles
36      const FinalState& fs = apply<FinalState>(event, "FS");
37      const size_t numParticles = fs.particles().size();
38
39      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
40      if (numParticles < 2) {
41        MSG_DEBUG("Failed leptonic event cut");
42        vetoEvent;
43      }
44      MSG_DEBUG("Passed leptonic event cut");
45
46      // Get beams and average beam momentum
47      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
48      const double meanBeamMom = ( beams.first.p3().mod() +
49                                   beams.second.p3().mod() ) / 2.0;
50      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
51
52      // Final state of unstable particles to get particle spectra
53      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
54
55      for (const Particle& p : ufs.particles()) {
56        const int id = p.abspid();
57        switch (id) {
58        case 22: // Photons
59          _histPhoton->fill(p.E());
60          break;
61        case 111: // Neutral pions
62          _histPi->fill(p.E());
63          break;
64        }
65      }
66
67    }
68
69
70    /// Normalise histograms etc., after the run
71    void finalize() {
72      scale(_histPhoton, sqrtS()/2./sumOfWeights());
73      scale(_histPi    , sqrtS()/2./sumOfWeights());
74    }
75
76    /// @}
77
78
79    /// @name Histograms
80    /// @{
81    Histo1DPtr _histPhoton;
82    Histo1DPtr _histPi    ;
83    /// @}
84
85
86  };
87
88
89  RIVET_DECLARE_PLUGIN(TPC_1985_I205868);
90
91
92}