Rivet analyses referenceBESIII_2021_I1845443Cross section for e+e−→pˉpη and pˉpω at energies between 3.773 and 4.600 GeVExperiment: BESIII (BEPC) Inspire ID: 1845443 Status: VALIDATED NOHEPDATA Authors:
Beam energies: (1.9, 1.9); (1.9, 1.9); (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); (2.2, 2.2); (2.2, 2.2); (2.3, 2.3) GeV Run details:
Cross section for e+e−→pˉpη and pˉpω at energies between 3.773 and 4.600 GeV measured by the BESIII collaboration. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples. Source code: BESIII_2021_I1845443.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- -> p pbar eta/omega
10 class BESIII_2021_I1845443 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2021_I1845443);
15
16
17 /// @name Analysis methods
18 ///@{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22 // Initialise and register projections
23 declare(FinalState(), "FS");
24 declare(UnstableParticles(), "UFS");
25 book(_nEta, 1,1,1);
26 book(_nOmega, 2,1,1);
27 for (const string& en : _nOmega.binning().edges<0>()) {
28 const double end = std::stod(en)*GeV;
29 if (isCompatibleWithSqrtS(end)) {
30 _ecms = en;
31 break;
32 }
33 }
34 if(_ecms.empty()) MSG_ERROR("Beam energy incompatible with analysis.");
35 }
36
37 void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
38 for (const Particle &child : p.children()) {
39 if(child.children().empty()) {
40 nRes[child.pid()]-=1;
41 --ncount;
42 }
43 else
44 findChildren(child,nRes,ncount);
45 }
46 }
47
48 /// Perform the per-event analysis
49 void analyze(const Event& event) {
50 const FinalState& fs = apply<FinalState>(event, "FS");
51 // total hadronic and muonic cross sections
52 map<long,int> nCount;
53 int ntotal(0);
54 for (const Particle& p : fs.particles()) {
55 nCount[p.pid()] += 1;
56 ++ntotal;
57 }
58 // find the eta/omega
59 const FinalState& ufs = apply<UnstableParticles>(event, "UFS");
60 for(const Particle& p : ufs.particles(Cuts::pid==PID::ETA or Cuts::pid==PID::OMEGA)) {
61 map<long,int> nRes = nCount;
62 int ncount = ntotal;
63 findChildren(p,nRes,ncount);
64 bool matched=true;
65 for(auto const & val : nRes) {
66 if(abs(val.first)==PID::PROTON) {
67 if(val.second!=1) {
68 matched = false;
69 break;
70 }
71 }
72 else if(val.second!=0) {
73 matched = false;
74 break;
75 }
76 }
77 if(matched) {
78 if(p.pid()==PID::ETA)
79 _nEta->fill(_ecms);
80 else
81 _nOmega->fill(_ecms);
82 break;
83 }
84 }
85 }
86
87
88 /// Normalise histograms etc., after the run
89 void finalize() {
90 double fact = crossSection()/ sumOfWeights() /picobarn;
91 scale(_nEta ,fact);
92 scale(_nOmega,fact);
93 }
94
95 ///@}
96
97
98 /// @name Histograms
99 ///@{
100 BinnedHistoPtr<string> _nEta,_nOmega;
101 string _ecms;
102 ///@}
103
104
105 };
106
107
108 RIVET_DECLARE_PLUGIN(BESIII_2021_I1845443);
109
110}
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