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CELLO_1987_I236981

Measurement of $R$ for energies between 14 and 46.6 GeV
Experiment: CELLO (PETRA)
Inspire ID: 236981
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. B183 (1987) 400-411, 1987
Beams: e- e+
Beam energies: ANY
Run details:
  • e+ e- to hadrons and e+ e- to mu+ mu- (for normalization)

Measurement of $R$ in $e^+e^-$ collisions for energies between 14 and 46.6 GeV. The individual hadronic and muonic cross sections are also outputted to the yoda file so that ratio $R$ can be recalculated if runs are combined.

Source code: CELLO_1987_I236981.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 CELLO_1987_I236981 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(CELLO_1987_I236981);
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      // counters for R
25      book(_c_hadrons, "/TMP/sigma_hadrons");
26      book(_c_muons, "/TMP/sigma_muons");
27    }
28
29
30    /// Perform the per-event analysis
31    void analyze(const Event& event) {
32      const FinalState& fs = apply<FinalState>(event, "FS");
33
34      map<long,int> nCount;
35      int ntotal(0);
36      for (const Particle& p : fs.particles()) {
37        nCount[p.pid()] += 1;
38        ++ntotal;
39      }
40      // mu+mu- + photons
41      if(nCount[-13]==1 and nCount[13]==1 &&
42         ntotal==2+nCount[22])
43        _c_muons->fill();
44      // everything else
45      else {
46        _c_hadrons->fill();
47      }
48    }
49
50
51    /// Normalise histograms etc., after the run
52    void finalize() {
53      Estimate0D R = *_c_hadrons/ *_c_muons;
54      double fact = crossSection()/ sumOfWeights() /picobarn;
55      double sig_h = _c_hadrons->val()*fact;
56      double err_h = _c_hadrons->err()*fact;
57      double sig_m = _c_muons  ->val()*fact;
58      double err_m = _c_muons  ->err()*fact;
59      Estimate1DPtr hadrons;
60      book(hadrons, "sigma_hadrons");
61      Estimate1DPtr muons;
62      book(muons, "sigma_muons"  );
63      Estimate1DPtr mult;
64      book(mult, 1, 1, 1);
65      for (auto& b : mult->bins()) {
66        if (inRange(sqrtS()/GeV, b.xMin(), b.xMax())) {
67          b.set(R.val(), R.errPos());
68          hadrons->bin(b.index()).set(sig_h, err_h);
69          muons  ->bin(b.index()).set(sig_m, err_m);
70        }
71      }
72    }
73
74    /// @}
75
76
77    /// @name Histograms
78    /// @{
79    CounterPtr _c_hadrons, _c_muons;
80    /// @}
81
82
83  };
84
85
86  RIVET_DECLARE_PLUGIN(CELLO_1987_I236981);
87
88
89}