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BABAR_2012_I1086164

Cross section for $e^+e^-\to 2\pi^+2\pi^-$ between 0.6 and 4.5 GeV
Experiment: BABAR (PEP-II)
Inspire ID: 1086164
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev. D85 (2012) 112009, 2012
Beams: e+ e-
Beam energies: (0.3, 0.3); (0.3, 0.3); (0.3, 0.3); (0.3, 0.3); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.4, 0.4); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.8, 0.8); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (0.9, 0.9); (1.0, 1.0); (1.0, 1.0); (1.0, 1.0); (1.0, 1.0); (1.0, 1.0); (1.0, 1.0); (1.0, 1.0); (1.0, 1.0); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.2, 1.2); (1.2, 1.2); (1.2, 1.2); (1.2, 1.2); (1.2, 1.2); (1.2, 1.2); (1.2, 1.2); (1.2, 1.2); (1.3, 1.3); (1.3, 1.3); (1.3, 1.3); (1.3, 1.3); (1.3, 1.3); (1.3, 1.3); (1.3, 1.3); (1.3, 1.3); (1.4, 1.4); (1.4, 1.4); (1.4, 1.4); (1.4, 1.4); (1.4, 1.4); (1.4, 1.4); (1.4, 1.4); (1.4, 1.4); (1.5, 1.5); (1.5, 1.5); (1.5, 1.5); (1.5, 1.5); (1.5, 1.5); (1.5, 1.5); (1.5, 1.5); (1.5, 1.5); (1.6, 1.6); (1.6, 1.6); (1.6, 1.6); (1.6, 1.6); (1.6, 1.6); (1.6, 1.6); (1.6, 1.6); (1.6, 1.6); (1.7, 1.7); (1.7, 1.7); (1.7, 1.7); (1.7, 1.7); (1.7, 1.7); (1.7, 1.7); (1.7, 1.7); (1.7, 1.7); (1.8, 1.8); (1.8, 1.8); (1.8, 1.8); (1.8, 1.8); (1.8, 1.8); (1.8, 1.8); (1.8, 1.8); (1.8, 1.8); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (2.0, 2.0); (2.0, 2.0); (2.0, 2.0); (2.0, 2.0); (2.0, 2.0); (2.0, 2.0); (2.0, 2.0); (2.0, 2.0); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2) GeV
Run details:
  • e+ e- to hadrons

Measurement of the cross section for $e^+e^-\to 2\pi^+2\pi^-$ using ISR by BaBar between 0.6 and 4.5 GeV. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples.

Source code: BABAR_2012_I1086164.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4
 5
 6namespace Rivet {
 7
 8
 9  /// @brief e+e- -> 2pi+2pi-
10  class BABAR_2012_I1086164 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2012_I1086164);
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, 1,1,1);
28      for (const string& en : _npion.binning().edges<0>()) {
29        const double end = std::stod(en)*MeV;
30        if (isCompatibleWithSqrtS(end)) {
31          _ecms = en;
32          break;
33        }
34      }
35      if (_ecms.empty())
36        MSG_ERROR("Beam energy incompatible with analysis.");
37    }
38
39
40    /// Perform the per-event analysis
41    void analyze(const Event& event) {
42      const FinalState& fs = apply<FinalState>(event, "FS");
43      if(fs.particles().size()!=4) vetoEvent;
44      for (const Particle& p : fs.particles()) {
45	if(abs(p.pid())!=PID::PIPLUS) vetoEvent;
46      }
47      _npion->fill(_ecms);
48    }
49
50
51    /// Normalise histograms etc., after the run
52    void finalize() {
53      scale(_npion, crossSection()/ sumOfWeights() /nanobarn);
54    }
55
56    /// @}
57
58
59    /// @name Histograms
60    /// @{
61    BinnedHistoPtr<string> _npion;
62    string _ecms;
63    /// @}
64
65
66  };
67
68
69  RIVET_DECLARE_PLUGIN(BABAR_2012_I1086164);
70
71
72}