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Rivet analyses reference

SND_1999_I508003

Cross section for $e^+e^-\to \pi^+\pi^-\pi^0$ between 1.04 and 1.38 GeV.
Experiment: SND (VEPP-2M)
Inspire ID: 508003
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. B462 (1999) 365-370, 1999
Beams: e+ e-
Beam energies: ANY
Run details:
  • e+ e- to hadrons

Measurement of the cross section for $e^+e^-\to \pi^+\pi^-\pi^0$ by SND for energies between 1.04 and 1.38 GeV.

Source code: SND_1999_I508003.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 SND_1999_I508003 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(SND_1999_I508003);
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(_num3pi, "TMP/num3");
27
28    }
29
30
31    /// Perform the per-event analysis
32    void analyze(const Event& event) {
33      const FinalState& fs = apply<FinalState>(event, "FS");
34
35      map<long,int> nCount;
36      int ntotal(0);
37      for (const Particle& p : fs.particles()) {
38	nCount[p.pid()] += 1;
39	++ntotal;
40      }
41      if(ntotal!=3) vetoEvent;
42      if(nCount[-211]==1&&nCount[211]==1&&nCount[111]==1)
43	_num3pi->fill();
44
45    }
46
47
48    /// Normalise histograms etc., after the run
49    void finalize() {
50
51      double sigma = _num3pi->val();
52      double error = _num3pi->err();
53      sigma *= crossSection()/ sumOfWeights() /nanobarn;
54      error *= crossSection()/ sumOfWeights() /nanobarn; 
55      Scatter2D temphisto(refData(1, 1, 1));
56      Scatter2DPtr mult;
57      book(mult, 1, 1, 1);
58      for (size_t b = 0; b < temphisto.numPoints(); b++) {
59	const double x  = temphisto.point(b).x();
60	pair<double,double> ex = temphisto.point(b).xErrs();
61	pair<double,double> ex2 = ex;
62	if(ex2.first ==0.) ex2. first=0.0001;
63	if(ex2.second==0.) ex2.second=0.0001;
64	if (inRange(sqrtS()/MeV, x-ex2.first, x+ex2.second)) {
65	  mult->addPoint(x, sigma, ex, make_pair(error,error));
66	}
67	else {
68	  mult->addPoint(x, 0., ex, make_pair(0.,.0));
69	}
70      }
71    }
72
73    //@}
74
75
76    /// @name Histograms
77    //@{
78    CounterPtr _num3pi;
79    //@}
80
81
82  };
83
84
85  // The hook for the plugin system
86  RIVET_DECLARE_PLUGIN(SND_1999_I508003);
87
88
89}