Rivet analyses referenceBABAR_2009_I829441Cross section for $e^+e^-\to \pi^+\pi^-$ below 3 GeVExperiment: BABAR (PEP-II) Inspire ID: 829441 Status: VALIDATED Authors:
Beam energies: ANY Run details:
1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4
5namespace Rivet {
6
7
8 /// @brief Add a short analysis description here
9 class BABAR_2009_I829441 : public Analysis {
10 public:
11
12 /// Constructor
13 RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2009_I829441);
14
15
16 /// @name Analysis methods
17 /// @{
18
19 /// Book histograms and initialise projections before the run
20 void init() {
21 // Initialise and register projections
22 declare(FinalState(), "FS");
23
24 // Book histograms
25 book(_npion, "TMP/pion");
26 }
27
28
29 /// Perform the per-event analysis
30 void analyze(const Event& event) {
31 const FinalState& fs = apply<FinalState>(event, "FS");
32 if(fs.particles().size()!=2) vetoEvent;
33 for (const Particle& p : fs.particles()) {
34 if(abs(p.pid())!=PID::PIPLUS) vetoEvent;
35 }
36 _npion->fill();
37 }
38
39
40 /// Normalise histograms etc., after the run
41 void finalize() {
42 double sigma = _npion->val();
43 double error = _npion->err();
44 sigma *= crossSection()/ sumOfWeights() /nanobarn;
45 error *= crossSection()/ sumOfWeights() /nanobarn;
46 Estimate1DPtr mult;
47 book(mult, 1, 1, 1);
48 for (auto& b : mult->bins()) {
49 if (inRange(sqrtS()/GeV, b.xMin(), b.xMax())) {
50 b.set(sigma, error);
51 }
52 }
53
54 }
55
56 /// @}
57
58
59 /// @name Histograms
60 /// @{
61 CounterPtr _npion;
62 /// @}
63
64
65 };
66
67
68 RIVET_DECLARE_PLUGIN(BABAR_2009_I829441);
69
70
71}
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