Rivet analyses referenceCMD2_2002_I568807Cross section for $e^+e^-\to \pi^+\pi^-$ at near the $\rho$ mass.Experiment: CMD2 (VEPP-2M) Inspire ID: 568807 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of the cross section for $e^+e^-\to \pi^+\pi^-$ at energies near the $\rho$ mass. Source code: CMD2_2002_I568807.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_2002_I568807 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(CMD2_2002_I568807);
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 /// Perform the per-event analysis
32 void analyze(const Event& event) {
33 const FinalState& fs = apply<FinalState>(event, "FS");
34 if(fs.particles().size()!=2) vetoEvent;
35 for (const Particle& p : fs.particles()) {
36 if(abs(p.pid())!=PID::PIPLUS) vetoEvent;
37 }
38 _npion->fill();
39 }
40
41
42 /// Normalise histograms etc., after the run
43 void finalize() {
44 double sigma = _npion->val();
45 double error = _npion->err();
46 sigma *= crossSection()/ sumOfWeights() /nanobarn;
47 error *= crossSection()/ sumOfWeights() /nanobarn;
48 Estimate1DPtr mult;
49 book(mult, 1, 1, 2);
50 for (auto& b : mult->bins()) {
51 if (inRange(sqrtS()/MeV, b.xMin(), b.xMax())) {
52 b.set(sigma, error);
53 }
54 }
55 }
56
57 /// @}
58
59
60 /// @name Histograms
61 /// @{
62 CounterPtr _npion;
63 /// @}
64
65
66 };
67
68
69 RIVET_DECLARE_PLUGIN(CMD2_2002_I568807);
70
71
72}
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