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BABAR_2021_I1937349

Cross section for $e^+e^-\to$ $\pi^+\pi^-\pi^0$ between 0.62 and 3.5 GeV
Experiment: BABAR (PEP-II)
Inspire ID: 1937349
Status: VALIDATED
Authors:
  • Peter Richardson
References: Beams: e+ e-
Beam energies: ANY
    No run details listed

Measurement of the cross section for $e^+e^-\to \pi^+\pi^-\pi^0$ by BaBar using radiative return for energies between 0.62 and 3.5 GeV. The contribution of the $J/\psi$ has been subtracted.

Source code: BABAR_2021_I1937349.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief e+e- -> pi+pi-pi0
 9  class BABAR_2021_I1937349 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2021_I1937349);
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(_num3pi, "TMP/num3");
26    }
27
28
29    /// Perform the per-event analysis
30    void analyze(const Event& event) {
31      const FinalState& fs = apply<FinalState>(event, "FS");
32
33      map<long,int> nCount;
34      int ntotal(0);
35      for (const Particle& p : fs.particles()) {
36	nCount[p.pid()] += 1;
37	++ntotal;
38      }
39      if(ntotal!=3) vetoEvent;
40      if(nCount[-211]==1&&nCount[211]==1&&nCount[111]==1)
41	_num3pi->fill();
42    }
43
44
45    /// Normalise histograms etc., after the run
46    void finalize() {
47      double sigma = _num3pi->val();
48      double error = _num3pi->err();
49      sigma *= crossSection()/ sumOfWeights() /nanobarn;
50      error *= crossSection()/ sumOfWeights() /nanobarn;
51      Estimate1DPtr  mult;
52      book(mult, 1, 1, 1);
53      for (auto& b : mult->bins()) {
54        if (inRange(sqrtS()/GeV, b.xMin(), b.xMax())) {
55          b.set(sigma, error);
56        }
57      }
58    }
59
60    ///@}
61
62
63    /// @name Histograms
64    ///@{
65    CounterPtr _num3pi;
66    ///@}
67
68
69  };
70
71
72  RIVET_DECLARE_PLUGIN(BABAR_2021_I1937349);
73
74}