Rivet analyses referenceSND_2005_I686349Cross section for $e^+e^-\to \pi^+\pi^-$ at energies between 0.4 and 1 GeVExperiment: SND (VEPP-2M) Inspire ID: 686349 Status: VALIDATED Authors:
Beam energies: ANY Run details:
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 SND_2005_I686349 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(SND_2005_I686349);
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, "TMP/pion");
28
29 }
30
31
32 /// Perform the per-event analysis
33 void analyze(const Event& event) {
34 const FinalState& fs = apply<FinalState>(event, "FS");
35 if(fs.particles().size()!=2) vetoEvent;
36 for (const Particle& p : fs.particles()) {
37 if(abs(p.pid())!=PID::PIPLUS) vetoEvent;
38 }
39 _npion->fill();
40 }
41
42
43 /// Normalise histograms etc., after the run
44 void finalize() {
45 double sigma = _npion->val();
46 double error = _npion->err();
47 sigma *= crossSection()/ sumOfWeights() /nanobarn;
48 error *= crossSection()/ sumOfWeights() /nanobarn;
49 Estimate1DPtr mult;
50 book(mult, 1, 1, 1);
51 for (auto& b : mult->bins()) {
52 if (inRange(sqrtS()/MeV, b.xMin(), b.xMax())) {
53 b.set(sigma, error);
54 }
55 }
56 }
57
58 /// @}
59
60
61 /// @name Histograms
62 /// @{
63 CounterPtr _npion;
64 /// @}
65
66
67 };
68
69
70 RIVET_DECLARE_PLUGIN(SND_2005_I686349);
71
72
73}
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