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CMD2_1998_I480170

Cross section for $e^+e^-\to \pi^+\pi^-\pi^0$ near the $\phi$ mass
Experiment: CMD2 (VEPP-2M)
Inspire ID: 480170
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. B434 (1998) 426-436, 1998
Beams: e+ e-
Beam energies: ANY
Run details:
  • e+ e- to hadrons

Measurement of the cross section for $e^+e^-\to \pi^+\pi^-\pi^0$ for energies near the $\phi$ mass.

Source code: CMD2_1998_I480170.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_1998_I480170 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(CMD2_1998_I480170);
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
48      double sigma = _num3pi->val();
49      double error = _num3pi->err();
50      sigma *= crossSection()/ sumOfWeights() /nanobarn;
51      error *= crossSection()/ sumOfWeights() /nanobarn; 
52      Scatter2D temphisto(refData(1, 1, 1));
53      Scatter2DPtr mult;
54      book(mult, 1, 1, 1);
55      for (size_t b = 0; b < temphisto.numPoints(); b++) {
56	const double x  = temphisto.point(b).x();
57	pair<double,double> ex = temphisto.point(b).xErrs();
58	pair<double,double> ex2 = ex;
59	if(ex2.first ==0.) ex2. first=0.0001;
60	if(ex2.second==0.) ex2.second=0.0001;
61	if (inRange(sqrtS()/MeV, x-ex2.first, x+ex2.second)) {
62	  mult->addPoint(x, sigma, ex, make_pair(error,error));
63	}
64	else {
65	  mult->addPoint(x, 0., ex, make_pair(0.,.0));
66	}
67      }
68    }
69
70    //@}
71
72
73    /// @name Histograms
74    //@{
75    CounterPtr _num3pi;
76    //@}
77
78
79  };
80
81
82  // The hook for the plugin system
83  RIVET_DECLARE_PLUGIN(CMD2_1998_I480170);
84
85
86}