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MARKI_1977_I119979

Measurement of $R$ for energies between 3.598 and 3.886 GeV
Experiment: MARKI (Spear)
Inspire ID: 119979
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev.Lett. 39 (1977) 526, 1977
Beams: e- e+
Beam energies: (1.8, 1.8); (1.8, 1.8); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9); (1.9, 1.9) GeV
Run details:
  • e+ e- to hadrons and e+ e- to mu+ mu- (for normalization)

Measurement of $R$ and the hadronic cross section for energies between 3.598 and 3.886 GeV. The hadronic and muonic cross sections are also outputted to the yoda file so that ratio $R$ can be recalcuated if runs are combined.

Source code: MARKI_1977_I119979.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief R measurement
 9  class MARKI_1977_I119979 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(MARKI_1977_I119979);
14
15
16    /// @name Analysis methods
17    /// @{
18
19    /// Book histograms and initialise projections before the run
20    void init() {
21      declare(FinalState(), "FS");
22      // Book histograms
23      book(_c_hadrons, "/TMP/sigma_hadrons", refData<YODA::BinnedEstimate<string>>(1,1,1));
24      book(_c_muons,   "/TMP/sigma_muons"  , refData<YODA::BinnedEstimate<string>>(1,1,1));
25      for (const string& en : _c_hadrons.binning().edges<0>()) {
26        double end = std::stod(en)*GeV;
27        if(isCompatibleWithSqrtS(end)) {
28          _ecms = en;
29          break;
30        }
31      }
32      if(_ecms.empty()) MSG_ERROR("Beam energy incompatible with analysis.");
33    }
34
35
36    /// Perform the per-event analysis
37    void analyze(const Event& event) {
38      const FinalState& fs = apply<FinalState>(event, "FS");
39
40      map<long,int> nCount;
41      int ntotal(0);
42      for (const Particle& p : fs.particles()) {
43	nCount[p.pid()] += 1;
44	++ntotal;
45      }
46      // mu+mu- + photons
47      if(nCount[-13]==1 and nCount[13]==1 &&
48	 ntotal==2+nCount[22])
49	_c_muons->fill(_ecms);
50      // everything else
51      else
52	_c_hadrons->fill(_ecms);
53    }
54
55
56    /// Normalise histograms etc., after the run
57    void finalize() {
58      BinnedEstimatePtr<string> mult;
59      book(mult, 1, 1, 1);
60      divide(_c_hadrons,_c_muons,mult);
61      book(mult, 2, 1, 1);
62      divide(_c_hadrons,_c_muons,mult);
63    }
64
65    /// @}
66
67
68    /// @name Histograms
69    /// @{
70    BinnedHistoPtr<string> _c_hadrons, _c_muons;
71    string _ecms;
72    /// @}
73
74
75  };
76
77
78  RIVET_DECLARE_PLUGIN(MARKI_1977_I119979);
79
80
81}