Rivet analyses referenceCMD2_2007_I728302Cross section for $e^+e^-\to \pi^+\pi^-$ between 600 and 970 MeVExperiment: CMD2 (VEPP-2M) Inspire ID: 728302 Status: VALIDATED Authors:
Beam energies: (0.3, 0.3); (0.3, 0.3); (0.3, 0.3); (0.3, 0.3); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5) GeV Run details:
Measurement of the cross section for $e^+e^-\to \pi^+\pi^-$ at energies between 600 and 970 MeV. Useful for comparing models of the pion form factor. Source code: CMD2_2007_I728302.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 CMD2_2007_I728302 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(CMD2_2007_I728302);
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, 2,1,1);
28 vector<int> enint({600, 630, 660, 690, 720, 750, 760, 764, 770, 774, 778, 780, 781, 782,
29 783, 784, 786, 790, 794, 800, 810, 820, 840, 880, 920, 940, 950, 958, 970});
30 icms=-1;
31 for(const int& en : enint) {
32 double end = double(en)*MeV;
33 if(isCompatibleWithSqrtS(end)) {
34 icms = en;
35 break;
36 }
37 }
38 if(icms<0) 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()!=2) vetoEvent;
46 for (const Particle& p : fs.particles()) {
47 if(abs(p.pid())!=PID::PIPLUS) vetoEvent;
48 }
49 _npion->fill(icms);
50 }
51
52
53 /// Normalise histograms etc., after the run
54 void finalize() {
55 scale(_npion,crossSection()/ sumOfWeights() /nanobarn);
56 }
57
58 /// @}
59
60
61 /// @name Histograms
62 /// @{
63 BinnedHistoPtr<int> _npion;
64 int icms;
65 /// @}
66
67
68 };
69
70
71 RIVET_DECLARE_PLUGIN(CMD2_2007_I728302);
72
73
74}
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