Rivet analyses referenceBESII_2006_I717665Measurement of $R$ for energies between 3.65 and 3.773 GeVExperiment: BESII (BEPC) Inspire ID: 717665 Status: VALIDATED SINGLEWEIGHT Authors:
Beam energies: (1.8, 1.8); (1.8, 1.8); (1.9, 1.9) GeV Run details:
Measurement of $R$ and the hadronic cross section in $e^+e^-$ collisions by BESII for energies between 3.65 and 3.773, in the vicinity of the $\psi(3770)$. The muonic cross section is also outputted to the yoda file so that ratio $R$ can be recalculated if runs are combined. Source code: BESII_2006_I717665.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 3.65 and 3.773 GeV
9 class BESII_2006_I717665 : public Analysis {
10 public:
11
12 /// Constructor
13 RIVET_DEFAULT_ANALYSIS_CTOR(BESII_2006_I717665);
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
24 // Book histograms
25 book(_c_hadrons, 2,1,1);
26 book(_c_muons, "/TMP/sigma_muons", refData<YODA::BinnedEstimate<string>>(2,1,1));
27 for (const string& en : _c_hadrons.binning().edges<0>()) {
28 double end = std::stod(en)*GeV;
29 if(isCompatibleWithSqrtS(end)) {
30 _ecms = en;
31 break;
32 }
33 }
34 if(_ecms.empty())
35 MSG_ERROR("Beam energy incompatible with analysis.");
36 }
37
38
39 /// Perform the per-event analysis
40 void analyze(const Event& event) {
41 const FinalState& fs = apply<FinalState>(event, "FS");
42
43 map<long,int> nCount;
44 int ntotal(0);
45 for (const Particle& p : fs.particles()) {
46 nCount[p.pid()] += 1;
47 ++ntotal;
48 }
49 // mu+mu- + photons
50 if(nCount[-13]==1 and nCount[13]==1 &&
51 ntotal==2+nCount[22])
52 _c_muons->fill(_ecms);
53 // everything else
54 else
55 _c_hadrons->fill(_ecms);
56 }
57
58
59 /// Normalise histograms etc., after the run
60 void finalize() {
61 BinnedEstimatePtr<string> mult;
62 book(mult,2,1,2);
63 divide(_c_hadrons, _c_muons, mult);
64 scale(_c_hadrons,crossSection()/ sumOfWeights() /nanobarn);
65 }
66
67 /// @}
68
69
70 /// @name Histograms
71 /// @{
72 BinnedHistoPtr<string> _c_hadrons, _c_muons;
73 string _ecms;
74 /// @}
75
76
77 };
78
79
80 RIVET_DECLARE_PLUGIN(BESII_2006_I717665);
81
82}
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