Rivet analyses referenceBELLE_2014_I1282602Cross section for $e^+e^-\to J/\psi K^+K^-$ at energies between 4.175 and 5.975 GeVExperiment: BELLE (KEKB) Inspire ID: 1282602 Status: VALIDATED Authors:
Beam energies: (2.1, 2.1); (2.1, 2.1); (2.2, 2.2); (2.2, 2.2); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.4, 2.4); (2.4, 2.4); (2.4, 2.4); (2.4, 2.4); (2.5, 2.5); (2.5, 2.5); (2.5, 2.5); (2.5, 2.5); (2.6, 2.6); (2.6, 2.6); (2.6, 2.6); (2.6, 2.6); (2.7, 2.7); (2.7, 2.7); (2.7, 2.7); (2.7, 2.7); (2.8, 2.8); (2.8, 2.8); (2.8, 2.8); (2.9, 2.9); (2.9, 2.9); (2.9, 2.9); (2.9, 2.9); (3.0, 3.0); (3.0, 3.0) GeV Run details:
Measurement of the cross section for $e^+e^-\to J/\psi K^+K^-$ at energies between 4.175 and 5.975 GeV using radiative return by BELLE. The paper also includes $J\psi K^0_SK^0_S$ but the data is a confidence limit and is therefore not implemented. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples. Source code: BELLE_2014_I1282602.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4#include "Rivet/Projections/UnstableParticles.hh"
5
6namespace Rivet {
7
8
9 /// @brief e+e- -> Jpsi K+K-
10 class BELLE_2014_I1282602 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2014_I1282602);
15
16
17 /// @name Analysis methods
18 /// @{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22 declare(FinalState(), "FS");
23 declare(UnstableParticles(), "UFS");
24 book(_nJPsi, 1,1,1);
25 for (const string& en : _nJPsi.binning().edges<0>()) {
26 const double end = std::stod(en)*GeV;
27 if (isCompatibleWithSqrtS(end)) {
28 _ecms = en;
29 break;
30 }
31 }
32 if (_ecms.empty())
33 MSG_ERROR("Beam energy incompatible with analysis.");
34 }
35
36 void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
37 for (const Particle &child : p.children()) {
38 if(child.children().empty()) {
39 --nRes[child.pid()];
40 --ncount;
41 }
42 else
43 findChildren(child,nRes,ncount);
44 }
45 }
46
47
48 /// Perform the per-event analysis
49 void analyze(const Event& event) {
50 const FinalState& fs = apply<FinalState>(event, "FS");
51 map<long,int> nCount;
52 int ntotal(0);
53 for (const Particle& p : fs.particles()) {
54 nCount[p.pid()] += 1;
55 ++ntotal;
56 }
57 const FinalState& ufs = apply<FinalState>(event, "UFS");
58 for (const Particle& p : ufs.particles()) {
59 if(p.children().empty()) continue;
60 // find the j/psi
61 if(p.pid()==443) {
62 map<long,int> nRes = nCount;
63 int ncount = ntotal;
64 findChildren(p,nRes,ncount);
65 // J/psi pi+pi-
66 if(ncount!=2) continue;
67 bool matched = true;
68 for(auto const & val : nRes) {
69 if(abs(val.first)==321) {
70 if(val.second !=1) {
71 matched = false;
72 break;
73 }
74 }
75 else if(val.second!=0) {
76 matched = false;
77 break;
78 }
79 }
80 if(matched) {
81 _nJPsi->fill(_ecms);
82 break;
83 }
84 }
85 }
86 }
87
88
89 /// Normalise histograms etc., after the run
90 void finalize() {
91 scale(_nJPsi, crossSection()/ sumOfWeights() /picobarn);
92 }
93
94 /// @}
95
96
97 /// @name Histograms
98 /// @{
99 BinnedHistoPtr<string> _nJPsi;
100 string _ecms;
101 /// @}
102
103
104 };
105
106
107 RIVET_DECLARE_PLUGIN(BELLE_2014_I1282602);
108
109
110}
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