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Rivet analyses reference

BESIII_2020_I1837725

Measurement of the cross section for $e^+e^-\to2p2\bar{p}$ for $E_{\text{CMS}}$ between 4 and 4.6 GeV
Experiment: BESIII (BEPC)
Inspire ID: 1837725
Status: VALIDATED
Authors:
  • Peter Richardson
References: Beams: e+ e-
Beam energies: (2.0, 2.0); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.3, 2.3) GeV
Run details:
  • e+ e- to hadrons

Measurement of the cross section for $e^+e^-\to2p2\bar{p}$ for $E_{\text{CMS}}$ between 4 and 4.6 GeV by the BESIII collaboration. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples.

Source code: BESIII_2020_I1837725.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4#include "Rivet/Projections/FastJets.hh"
 5#include "Rivet/Projections/LeptonFinder.hh"
 6#include "Rivet/Projections/MissingMomentum.hh"
 7#include "Rivet/Projections/PromptFinalState.hh"
 8
 9namespace Rivet {
10
11
12  /// @brief e+e- > 2p 2pbar
13  class BESIII_2020_I1837725 : public Analysis {
14  public:
15
16    /// Constructor
17    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2020_I1837725);
18
19
20    /// @name Analysis methods
21    ///@{
22
23    /// Book histograms and initialise projections before the run
24    void init() {
25
26      // Initialise and register projections
27      declare(FinalState(), "FS");
28
29      // Book histograms
30      book(_nproton, 1, 1, 1);
31      for (const string& en : _nproton.binning().edges<0>()) {
32        const double end = std::stod(en)*GeV;
33        if (isCompatibleWithSqrtS(end)) {
34          _ecms = en;
35          break;
36        }
37      }
38      if(_ecms.empty()) MSG_ERROR("Beam energy incompatible with analysis.");
39    }
40
41
42    /// Perform the per-event analysis
43    void analyze(const Event& event) {
44      const FinalState& fs = apply<FinalState>(event, "FS");
45      if(fs.particles().size()!=4) vetoEvent;
46      for (const Particle& p :  fs.particles()) {
47	if(abs(p.pid())!=PID::PROTON) vetoEvent;
48      }
49      _nproton->fill(_ecms);
50    }
51
52
53    /// Normalise histograms etc., after the run
54    void finalize() {
55      scale(_nproton, crossSection()/ sumOfWeights() /femtobarn);
56    }
57
58    ///@}
59
60
61    /// @name Histograms
62    ///@{
63    BinnedHistoPtr<string> _nproton;
64    string _ecms;
65    ///@}
66
67
68  };
69
70
71  RIVET_DECLARE_PLUGIN(BESIII_2020_I1837725);
72
73}