Rivet analyses referenceBESII_2009_I814778Measurement of $R$ for energies between 2.6 and 3.65 GeVExperiment: BESII (BEPC) Inspire ID: 814778 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of $R$ in $e^+e^-$ collisions by BESII for energies between 2.6 and 3.65 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: BESII_2009_I814778.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4
5namespace Rivet {
6
7
8 /// @brief Measurement of $R$ for energies between 2.6 and 3.65 GeV
9 class BESII_2009_I814778 : public Analysis {
10 public:
11
12 /// Constructor
13 RIVET_DEFAULT_ANALYSIS_CTOR(BESII_2009_I814778);
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(_c_hadrons, "/TMP/sigma_hadrons");
25 book(_c_muons, "/TMP/sigma_muons");
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 // mu+mu- + photons
40 if(nCount[-13]==1 and nCount[13]==1 &&
41 ntotal==2+nCount[22])
42 _c_muons->fill();
43 // everything else
44 else
45 _c_hadrons->fill();
46 }
47
48
49 /// Normalise histograms etc., after the run
50 void finalize() {
51 Estimate0D R = *_c_hadrons/ *_c_muons;
52 double fact = crossSection()/ sumOfWeights() /nanobarn;
53 double sig_h = _c_hadrons->val()*fact;
54 double err_h = _c_hadrons->err()*fact;
55 double sig_m = _c_muons ->val()*fact;
56 double err_m = _c_muons ->err()*fact;
57 Estimate1DPtr hadrons;
58 book(hadrons, "sigma_hadrons");
59 Estimate1DPtr muons;
60 book(muons, "sigma_muons" );
61 Estimate1DPtr mult;
62 book(mult, 1, 1, 1);
63 for (auto& b : mult->bins()) {
64 if (inRange(sqrtS()/GeV, b.xMin(), b.xMax())) {
65 b.set(R.val(), R.errPos());
66 hadrons->bin(b.index()).set(sig_h, err_h);
67 muons ->bin(b.index()).set(sig_m, err_m);
68 }
69 }
70 }
71
72 /// @}
73
74
75 /// @name Histograms
76 /// @{
77 CounterPtr _c_hadrons, _c_muons;
78 /// @}
79
80
81 };
82
83
84 RIVET_DECLARE_PLUGIN(BESII_2009_I814778);
85
86
87}
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