1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief e+e- -> pi0 gamma
 9  class SND_2018_I1694988 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(SND_2018_I1694988);
14
15
16    /// @name Analysis methods
17    /// @{
18
19    /// Book histograms and initialise projections before the run
20    void init() {
21      declare(FinalState(), "FS");
22      book(_numPi0Gamma, 1, 1, 1);
23    }
24
25
26    /// Perform the per-event analysis
27    void analyze(const Event& event) {
28
29      const FinalState& fs = apply<FinalState>(event, "FS");
30
31      map<long,int> nCount;
32      int ntotal(0);
33      for (const Particle& p : fs.particles()) {
34	nCount[p.pid()] += 1;
35	++ntotal;
36      }
37      if(ntotal==2 && nCount[22]==1 && nCount[111]==1)
38	_numPi0Gamma->fill(round(sqrtS()/MeV));
39    }
40
41
42    /// Normalise histograms etc., after the run
43    void finalize() {
44      scale(_numPi0Gamma, crossSection()/ sumOfWeights() /picobarn);
45    }
46
47    /// @}
48
49
50    /// @name Histograms
51    /// @{
52    BinnedHistoPtr<int> _numPi0Gamma;
53    /// @}
54
55
56  };
57
58
59  RIVET_DECLARE_PLUGIN(SND_2018_I1694988);
60
61
62}