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 CLEO_1986_I220652 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(CLEO_1986_I220652);
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      // histos
25      book(_h,1,1,1);
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()) continue;
42	LorentzTransform boost;
43	if (ups.p3().mod() > 1*MeV)
44	  boost = LorentzTransform::mkFrameTransformFromBeta(ups.momentum().betaVec());
45	for(const Particle & gamma:photons) {
46	  double E = boost.transform(gamma.momentum()).E();
47	  E = randnorm(E,0.21*sqrt(E));
48	  _h->fill(2.*E/ups.mass());
49	}
50      }
51    }
52
53
54    /// Normalise histograms etc., after the run
55    void finalize() {
56      normalize(_h,1.,false);
57    }
58
59    /// @}
60
61
62    /// @name Histograms
63    /// @{
64    Histo1DPtr _h;
65    /// @}
66
67
68  };
69
70
71  RIVET_DECLARE_PLUGIN(CLEO_1986_I220652);
72
73}