1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/UnstableParticles.hh"
 4#include "Rivet/Tools/Random.hh"
 5
 6namespace Rivet {
 7
 8
 9  /// @brief direct photon spectrum in upslion decay
10  class ARGUS_1987_I248655 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1987_I248655);
15
16
17    /// @name Analysis methods
18    /// @{
19
20    /// Book histograms and initialise projections before the run
21    void init() {
22      // projections
23      declare(UnstableParticles(Cuts::pid==553), "UFS");
24      book(_h_gamma,2,1,1);
25      book(_n_Ups,"TMP/nUps");
26    }
27
28
29    /// Perform the per-event analysis
30    void analyze(const Event& event) {
31      // Find the Upsilons among the unstables
32      for (const Particle& ups : apply<UnstableParticles>(event, "UFS").particles()) {
33	unsigned int nhadron(0);
34	Particles photons;
35	for(const Particle & child : ups.children()) {
36	  if(PID::isHadron(child.pid()))
37	    ++nhadron;
38	  else if(child.pid()==PID::PHOTON)
39	    photons.push_back(child);
40	}
41	if(nhadron!=0 && photons.empty()) {
42	  _n_Ups->fill();
43	}
44	else if(nhadron!=0) {
45	  LorentzTransform boost;
46	  if (ups.p3().mod() > 1*MeV)
47	    boost = LorentzTransform::mkFrameTransformFromBeta(ups.momentum().betaVec());
48	  for(const Particle & gamma:photons) {
49	    double E = boost.transform(gamma.momentum()).E();
50	    E = randnorm(E,sqrt(sqr(0.072)+sqr(0.065)/E)*E);
51	    _h_gamma->fill(2.*E/ups.mass());
52	  }
53	}
54      }
55    }
56
57
58    /// Normalise histograms etc., after the run
59    void finalize() {
60      scale(_h_gamma, 1./ *_n_Ups);
61    }
62
63    /// @}
64
65
66    /// @name Histograms
67    /// @{
68    Histo1DPtr _h_gamma;
69    CounterPtr _n_Ups;
70    /// @}
71
72
73  };
74
75
76  RIVET_DECLARE_PLUGIN(ARGUS_1987_I248655);
77
78}