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CMD2_2000_I511375

Cross section for $e^+e^-\to\pi^+\pi^+\pi^-\pi^+$ below 1 GeV
Experiment: CMD2 (VEPP-2M)
Inspire ID: 511375
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. B475 (2000) 190-197, 2000
Beams: e+ e-
Beam energies: ANY
Run details:
  • e+e- to hadrons

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}