Rivet analyses referenceCMD2_2000_I511375Cross section for $e^+e^-\to\pi^+\pi^+\pi^-\pi^+$ below 1 GeVExperiment: CMD2 (VEPP-2M) Inspire ID: 511375 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of the cross section for $e^+e^-\to\pi^+\pi^+\pi^-\pi^+$ below 1 GeV Source code: CMD2_2000_I511375.cc 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 CMD2_2000_I511375 : public Analysis {
10 public:
11
12 /// Constructor
13 RIVET_DEFAULT_ANALYSIS_CTOR(CMD2_2000_I511375);
14
15
16 /// @name Analysis methods
17 /// @{
18
19 /// Book histograms and initialise projections before the run
20 void init() {
21
22 // Initialise and register projections
23 declare(FinalState(), "FS");
24
25 // Book histograms
26 book(_npion, "TMP/pion");
27 }
28
29
30 /// Perform the per-event analysis
31 void analyze(const Event& event) {
32 const FinalState& fs = apply<FinalState>(event, "FS");
33 if(fs.particles().size()!=4) vetoEvent;
34 for (const Particle& p : fs.particles()) {
35 if(abs(p.pid())!=PID::PIPLUS) vetoEvent;
36 }
37 _npion->fill();
38
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, 1);
50 for (auto& b : mult->bins()) {
51 if (inRange(sqrtS()/GeV, 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_2000_I511375);
70
71
72}
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