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DM1_1982_I168552

Cross section for $e^+e^-\to\pi^+\pi^+\pi^-\pi^+$ between 1.4 and 2.18 GeV
Experiment: DM1 (DCI)
Inspire ID: 168552
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. B109 (1982) 129-132, 1982
Beams: e+ e-
Beam energies: ANY
Run details:
  • e+e- to hadrons

Measurement of the cross section for $e^+e^-\to\pi^+\pi^+\pi^-\pi^+$ between 1.4 and 2.18 GeV

Source code: DM1_1982_I168552.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 DM1_1982_I168552 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(DM1_1982_I168552);
14
15
16    /// @name Analysis methods
17    //@{
18
19    /// Book histograms and initialise projections before the run
20    void init() {
21      // Initialise and register projections
22      declare(FinalState(), "FS");
23      // Book histograms
24      book(_npion, "TMP/pion");
25    }
26
27
28    /// Perform the per-event analysis
29    void analyze(const Event& event) {
30      const FinalState& fs = apply<FinalState>(event, "FS");
31      if(fs.particles().size()!=4) vetoEvent;
32      for (const Particle& p : fs.particles()) {
33	if(abs(p.pid())!=PID::PIPLUS) vetoEvent;
34      }
35      _npion->fill();
36    }
37
38
39    /// Normalise histograms etc., after the run
40    void finalize() {
41      double sigma = _npion->val();
42      double error = _npion->err();
43      sigma *= crossSection()/ sumOfWeights() /nanobarn;
44      error *= crossSection()/ sumOfWeights() /nanobarn; 
45      Scatter2D temphisto(refData(1, 1, 1));
46      Scatter2DPtr mult;
47      book(mult, 1, 1, 1);
48      for (size_t b = 0; b < temphisto.numPoints(); b++) {
49	const double x  = temphisto.point(b).x();
50	pair<double,double> ex = temphisto.point(b).xErrs();
51	pair<double,double> ex2 = ex;
52	if(ex2.first ==0.) ex2. first=0.0001;
53	if(ex2.second==0.) ex2.second=0.0001;
54	if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
55	  mult->addPoint(x, sigma, ex, make_pair(error,error));
56	}
57	else {
58	  mult->addPoint(x, 0., ex, make_pair(0.,.0));
59	}
60      }
61    }
62
63    //@}
64
65
66    /// @name Histograms
67    //@{
68    CounterPtr _npion;
69    //@}
70
71
72  };
73
74
75  // The hook for the plugin system
76  RIVET_DECLARE_PLUGIN(DM1_1982_I168552);
77
78
79}