1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/UnstableParticles.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief J/psi spectrum in Upsilon(4S) decays
 9  class CLEO_1986_I230961 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(CLEO_1986_I230961);
14
15
16    /// @name Analysis methods
17    /// @{
18
19    /// Book histograms and initialise projections before the run
20    void init() {
21      // projections
22      declare(UnstableParticles(Cuts::pid==300553), "UFS");
23      // histos
24      book(_h,2,1,1);
25    }
26
27    /// Recursively walk the decay tree to find decay products of @a p
28    void findDecayProducts(Particle mother, Particles& unstable) {
29      for(const Particle& p: mother.children()) {
30        const int id = abs(p.pid());
31        if (id == 443) {
32          unstable.push_back(p);
33        }
34        else if(!p.children().empty()) {
35          findDecayProducts(p, unstable);
36        }
37      }
38    }
39
40
41    /// Perform the per-event analysis
42    void analyze(const Event& event) {
43      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
44      for (const Particle& ups : ufs.particles()) {
45        Particles unstable;
46        // Find the decay products we want
47        findDecayProducts(ups,unstable);
48        LorentzTransform cms_boost;
49        if (ups.p3().mod() > 0.001) {
50          cms_boost = LorentzTransform::mkFrameTransformFromBeta(ups.mom().betaVec());
51        }
52        for (const Particle& p : unstable) {
53          const double modp = cms_boost.transform(p.mom()).p3().mod();
54          _h->fill(modp);
55        }
56      }
57    }
58
59
60    /// Normalise histograms etc., after the run
61    void finalize() {
62      normalize(_h, 1.0, false);
63    }
64
65    /// @}
66
67
68    /// @name Histograms
69    /// @{
70    Histo1DPtr _h;
71    /// @}
72
73
74  };
75
76
77  RIVET_DECLARE_PLUGIN(CLEO_1986_I230961);
78
79}