Rivet analyses referenceBESIII_2023_I2688611Cross section for $e^+e^-\to\eta\phi$ for centre-of-mass energies between 3.773 and 4.6 GeVExperiment: BESIII (BEPC) Inspire ID: 2688611 Status: VALIDATED NOHEPDATA Authors:
Beam energies: (1.9, 1.9); (2.0, 2.0); (2.0, 2.0); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3) GeV Run details:
Measurement of the cross section for $e^+e^-\to\eta\phi$ for centre-of-mass energies between 3.773 and 4.6 GeV by the BESIII collaboration. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples. Source code: BESIII_2023_I2688611.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- > eta phi
10 class BESIII_2023_I2688611 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2023_I2688611);
15
16
17 /// @name Analysis methods
18 /// @{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22
23 // Initialise and register projections
24 declare(FinalState(), "FS");
25 declare(UnstableParticles(), "UFS");
26 book(_sigmaPhiEta,1,1,1);
27
28 for (const string& en : _sigmaPhiEta.binning().edges<0>()) {
29 double end = std::stod(en)*GeV;
30 if(isCompatibleWithSqrtS(end)) {
31 _ecms = en;
32 break;
33 }
34 }
35 if(_ecms.empty()) MSG_ERROR("Beam energy incompatible with analysis.");
36 }
37
38 void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
39 for (const Particle& child : p.children()) {
40 if (child.children().empty()) {
41 nRes[child.pid()]-=1;
42 --ncount;
43 }
44 else {
45 findChildren(child,nRes,ncount);
46 }
47 }
48 }
49
50 /// Perform the per-event analysis
51 void analyze(const Event& event) {
52 const FinalState& fs = apply<FinalState>(event, "FS");
53
54 map<long,int> nCount;
55 int ntotal(0);
56 for (const Particle& p : fs.particles()) {
57 nCount[p.pid()] += 1;
58 ++ntotal;
59 }
60 const FinalState& ufs = apply<FinalState>(event, "UFS");
61 // loop over eta mesons
62 for (const Particle& p : ufs.particles(Cuts::pid==221)) {
63 if (p.children().empty()) continue;
64 map<long,int> nRes = nCount;
65 int ncount = ntotal;
66 findChildren(p,nRes,ncount);
67 // loop over phi mesons
68 for (const Particle& p2 : ufs.particles(Cuts::pid==333)) {
69 if (p2.parents()[0].isSame(p)) continue;
70 map<long,int> nResB = nRes;
71 int ncountB = ncount;
72 findChildren(p2,nResB,ncountB);
73 if (ncountB!=0) continue;
74 bool matched = true;
75 for (const auto& val : nResB) {
76 if (val.second!=0) {
77 matched = false;
78 break;
79 }
80 }
81 if(matched) _sigmaPhiEta->fill(_ecms);
82 }
83 }
84 }
85
86
87 /// Normalise histograms etc., after the run
88 void finalize() {
89 scale(_sigmaPhiEta, crossSection()/ sumOfWeights()/picobarn);
90 }
91
92 /// @}
93
94
95 /// @name Histograms
96 /// @{
97 BinnedHistoPtr<string> _sigmaPhiEta;
98 string _ecms;
99 /// @}
100
101
102 };
103
104
105 RIVET_DECLARE_PLUGIN(BESIII_2023_I2688611);
106
107}
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