Rivet analyses referenceSND_2018_I1694988Cross section for $e^+e^-\to\pi\gamma$ for energies between 1.075 GeV and 2 GeVExperiment: SND (VEPP-2M) Inspire ID: 1694988 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Cross section for $e^+e^-\to\pi\gamma$ for energies between 1.075 GeV and 2 GeV Source code: SND_2018_I1694988.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4
5namespace Rivet {
6
7
8 /// @brief Add a short analysis description here
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, "TMP/Pi0Gamma");
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();
39 }
40
41
42 /// Normalise histograms etc., after the run
43 void finalize() {
44 double sigma = _numPi0Gamma->val();
45 double error = _numPi0Gamma->err();
46 sigma *= crossSection()/ sumOfWeights() /picobarn;
47 error *= crossSection()/ sumOfWeights() /picobarn;
48 Scatter2D temphisto(refData(1, 1, 1));
49 Scatter2DPtr mult;
50 book(mult, 1, 1, 1);
51 for (size_t b = 0; b < temphisto.numPoints(); b++) {
52 const double x = temphisto.point(b).x();
53 pair<double,double> ex = temphisto.point(b).xErrs();
54 pair<double,double> ex2 = ex;
55 if(ex2.first ==0.) ex2. first=0.0001;
56 if(ex2.second==0.) ex2.second=0.0001;
57 if (inRange(sqrtS()/MeV, x-ex2.first, x+ex2.second)) {
58 mult->addPoint(x, sigma, ex, make_pair(error,error));
59 }
60 else {
61 mult->addPoint(x, 0., ex, make_pair(0.,.0));
62 }
63 }
64 }
65
66 //@}
67
68
69 /// @name Histograms
70 //@{
71 CounterPtr _numPi0Gamma;
72 //@}
73
74
75 };
76
77
78 // The hook for the plugin system
79 RIVET_DECLARE_PLUGIN(SND_2018_I1694988);
80
81
82}
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