Rivet analyses referenceSND_2016_I1418483Cross section for $e^+e^-\to\pi\gamma$ for energies between 600 MeV and 1380 MeVExperiment: SND (VEPP-2M) Inspire ID: 1418483 Status: VALIDATED Authors:
Beam energies: ANY Run details:
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 Scatter2D temphisto(refData(1, 1, 5));
51 Scatter2DPtr mult;
52 book(mult, 1, 1, 5);
53 for (size_t b = 0; b < temphisto.numPoints(); b++) {
54 const double x = temphisto.point(b).x();
55 pair<double,double> ex = temphisto.point(b).xErrs();
56 pair<double,double> ex2 = ex;
57 if(ex2.first ==0.) ex2. first=0.0001;
58 if(ex2.second==0.) ex2.second=0.0001;
59 if (inRange(sqrtS()/MeV, x-ex2.first, x+ex2.second)) {
60 mult->addPoint(x, sigma, ex, make_pair(error,error));
61 }
62 else {
63 mult->addPoint(x, 0., ex, make_pair(0.,.0));
64 }
65 }
66 }
67
68 //@}
69
70
71 /// @name Histograms
72 //@{
73 CounterPtr _numPi0Gamma;
74 //@}
75
76
77 };
78
79
80 // The hook for the plugin system
81 RIVET_DECLARE_PLUGIN(SND_2016_I1418483);
82
83
84}
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