Rivet analyses referenceDM2_1989_I267118Cross section for $e^+e^-\to \pi^+\pi^-$ between 1.35 and 2.4 GeVExperiment: DM2 (DCI) Inspire ID: 267118 Status: VALIDATED Authors:
Beam energies: (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (1.0, 1.0); (1.0, 1.0); (1.0, 1.0); (1.0, 1.0); (1.1, 1.1) GeV Run details:
Measurement of the cross section for $e^+e^-\to \pi^+\pi^-$ at energies between 1.35 and 2.4 GeV. Useful for comparing models of the pion form factor. Source code: DM2_1989_I267118.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4
5
6namespace Rivet {
7
8
9 /// @brief e+e- > pi+pi-
10 class DM2_1989_I267118 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(DM2_1989_I267118);
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
26 // Book histograms
27 book(_npion,1,1,1);
28 for (const string& en : _npion.binning().edges<0>()) {
29 double end = std::stod(en)*GeV;
30 if(isCompatibleWithSqrtS(end)) {
31 ecms = en;
32 break;
33 }
34 }
35 if(ecms.empty()) 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::PIPLUS) vetoEvent;
45 }
46 _npion->fill(ecms);
47 }
48
49
50 /// Normalise histograms etc., after the run
51 void finalize() {
52 scale(_npion,crossSection()/ sumOfWeights() /nanobarn);
53 }
54
55 /// @}
56
57
58 /// @name Histograms
59 /// @{
60 BinnedHistoPtr<string> _npion;
61 string ecms;
62 /// @}
63
64
65 };
66
67
68 RIVET_DECLARE_PLUGIN(DM2_1989_I267118);
69
70
71}
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