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 OPAL Delta++ fragmentation function paper
12  ///
13  /// @author Peter Richardson
14  class OPAL_1995_I398320 : public Analysis {
15  public:
16
17    RIVET_DEFAULT_ANALYSIS_CTOR(OPAL_1995_I398320);
18
19
20    /// @name Analysis methods
21    /// @{
22
23    void init() {
24      declare(Beam(), "Beams");
25      declare(ChargedFinalState(), "FS");
26      declare(UnstableParticles(), "UFS");
27      book(_histXpDelta, 1, 1, 1);
28    }
29
30
31    void analyze(const Event& e) {
32      // First, veto on leptonic events by requiring at least 4 charged FS particles
33      const FinalState& fs = apply<FinalState>(e, "FS");
34      const size_t numParticles = fs.particles().size();
35
36      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
37      if (numParticles < 2) {
38        MSG_DEBUG("Failed leptonic event cut");
39        vetoEvent;
40      }
41      MSG_DEBUG("Passed leptonic event cut");
42
43      // Get beams and average beam momentum
44      const ParticlePair& beams = apply<Beam>(e, "Beams").beams();
45      const double meanBeamMom = ( beams.first.p3().mod() +
46                                   beams.second.p3().mod() ) / 2.0;
47      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
48
49      // Final state of unstable particles to get particle spectra
50      const UnstableParticles& ufs = apply<UnstableParticles>(e, "UFS");
51
52      for (const Particle& p : ufs.particles()) {
53        if(p.abspid()==2224) {
54          double xp = p.p3().mod()/meanBeamMom;
55          _histXpDelta->fill(xp);
56        }
57      }
58    }
59
60
61    /// Finalize
62    void finalize() {
63      scale(_histXpDelta, 1./sumOfWeights());
64    }
65
66    /// @}
67
68
69  private:
70
71      Histo1DPtr _histXpDelta;
72
73  };
74
75
76
77  RIVET_DECLARE_ALIASED_PLUGIN(OPAL_1995_I398320, OPAL_1995_S3198391);
78
79}