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SND_2016_I1418483

Cross section for $e^+e^-\to\pi\gamma$ for energies between 600 MeV and 1380 MeV
Experiment: SND (VEPP-2M)
Inspire ID: 1418483
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev. D93 (2016) no.9, 092001
Beams: e+ e-
Beam energies: ANY
Run details:
  • e+ e- to hadrons

Cross section for $e^+e^-\to\pi\gamma$ for energies between 600 MeV and 1380 MeV

Source code: SND_2016_I1418483.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4
 5
 6namespace Rivet {
 7
 8
 9  /// @brief Add a short analysis description here
10  class SND_2016_I1418483 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(SND_2016_I1418483);
15
16
17    /// @name Analysis methods
18    /// @{
19
20    /// Book histograms and initialise projections before the run
21    void init() {
22      declare(FinalState(), "FS");
23      book(_numPi0Gamma, "TMP/Pi0Gamma");
24    }
25
26
27    /// Perform the per-event analysis
28    void analyze(const Event& event) {
29
30      const FinalState& fs = apply<FinalState>(event, "FS");
31
32      map<long,int> nCount;
33      int ntotal(0);
34      for (const Particle& p : fs.particles()) {
35	nCount[p.pid()] += 1;
36	++ntotal;
37      }
38      if(ntotal==2 && nCount[22]==1 && nCount[111]==1)
39	_numPi0Gamma->fill();
40
41    }
42
43
44    /// Normalise histograms etc., after the run
45    void finalize() {
46      double sigma = _numPi0Gamma->val();
47      double error = _numPi0Gamma->err();
48      sigma *= crossSection()/ sumOfWeights() /nanobarn;
49      error *= crossSection()/ sumOfWeights() /nanobarn;
50      Estimate1DPtr mult;
51      book(mult, 1, 1, 5);
52      for (auto& b : mult->bins()) {
53        if (inRange(sqrtS()/MeV, b.xMin(), b.xMax())) {
54          b.set(sigma, error);
55        }
56      }
57    }
58
59    /// @}
60
61
62    /// @name Histograms
63    /// @{
64    CounterPtr _numPi0Gamma;
65    /// @}
66
67
68  };
69
70
71  RIVET_DECLARE_PLUGIN(SND_2016_I1418483);
72
73
74}