Rivet analyses referenceBESIII_2014_I1286898Cross section for $e^+e^-\to$ proton and antiproton between 3.65 and 3.9 GeVExperiment: BESIII (BEPC) Inspire ID: 1286898 Status: VALIDATED Authors:
Beam energies: (1.8, 1.8); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9) GeV Run details:
Measurement of the cross section for $e^+e^-\to p\bar{p}$ for energies between 3.65 and 3.9 GeV. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples. Source code: BESIII_2014_I1286898.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4
5namespace Rivet {
6
7
8 /// @brief Cross section for $e^+e^-\to$ proton and antiproton between 3.65 and 3.9 GeV
9 class BESIII_2014_I1286898 : public Analysis {
10 public:
11
12 /// Constructor
13 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2014_I1286898);
14
15
16 /// @name Analysis methods
17 /// @{
18
19 /// Book histograms and initialise projections before the run
20 void init() {
21
22 // Initialise and register projections
23 declare(FinalState(), "FS");
24
25 // Book histograms
26 book(_nproton, 1, 1, 6);
27 for (const string& en : _nproton.binning().edges<0>()) {
28 const double end = std::stod(en)*GeV;
29 if (isCompatibleWithSqrtS(end)) {
30 _ecms = en;
31 break;
32 }
33 }
34 if (_ecms.empty())
35 MSG_ERROR("Beam energy incompatible with analysis.");
36 }
37
38
39 /// Perform the per-event analysis
40 void analyze(const Event& event) {
41 const FinalState& fs = apply<FinalState>(event, "FS");
42 if(fs.particles().size()!=2) vetoEvent;
43 for (const Particle& p : fs.particles()) {
44 if(abs(p.pid())!=PID::PROTON) vetoEvent;
45 }
46 _nproton->fill(_ecms);
47 }
48
49
50 /// Normalise histograms etc., after the run
51 void finalize() {
52 scale(_nproton, crossSection()/ sumOfWeights() /picobarn);
53 }
54
55 /// @}
56
57
58 /// @name Histograms
59 /// @{
60 BinnedHistoPtr<string> _nproton;
61 string _ecms;
62 /// @}
63
64
65 };
66
67
68 RIVET_DECLARE_PLUGIN(BESIII_2014_I1286898);
69
70}
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