Rivet analyses referenceSND_2002_I587084Cross section for $e^+e^-\to\pi^0\pi^0\gamma$ at energies between 0.6 and 0.97 GeV.Experiment: SND (VEPP-2M) Inspire ID: 587084 Status: VALIDATED Authors:
Beam energies: ANY Run details:
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_2002_I587084 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(SND_2002_I587084);
15
16
17 /// @name Analysis methods
18 /// @{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22
23 // Initialise and register projections
24 declare(FinalState(), "FS");
25 book(_numPiPiGamma, "TMP/PiPiGamma");
26
27 }
28
29
30 /// Perform the per-event analysis
31 void analyze(const Event& event) {
32
33 const FinalState& fs = apply<FinalState>(event, "FS");
34
35 map<long,int> nCount;
36 int ntotal(0);
37 for (const Particle& p : fs.particles()) {
38 nCount[p.pid()] += 1;
39 ++ntotal;
40 }
41 // three particles (pi0 pi0 gamma)
42 if(ntotal!=3) vetoEvent;
43 if(nCount[111]==2 && nCount[22]==1)
44 _numPiPiGamma->fill();
45 }
46
47
48 /// Normalise histograms etc., after the run
49 void finalize() {
50
51 double sigma = _numPiPiGamma->val();
52 double error = _numPiPiGamma->err();
53 sigma *= crossSection()/ sumOfWeights() /nanobarn;
54 error *= crossSection()/ sumOfWeights() /nanobarn;
55 Estimate1DPtr mult;
56 book(mult, 1, 1, 1);
57 for (auto& b : mult->bins()) {
58 if (inRange(sqrtS()/MeV, b.xMin(), b.xMax())) {
59 b.set(sigma, error);
60 }
61 }
62 }
63
64 /// @}
65
66
67 /// @name Histograms
68 /// @{
69 CounterPtr _numPiPiGamma;
70 /// @}
71
72
73 };
74
75
76 RIVET_DECLARE_PLUGIN(SND_2002_I587084);
77
78
79}
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