Rivet analyses referenceBESIII_2020_I1762922Cross Section for $e^+e^-\to\eta^\prime J/\psi$ for energies between 4.178 and 4.6 GeVExperiment: BESIII (BEPC) Inspire ID: 1762922 Status: VALIDATED Authors:
Beam energies: (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 $e^+e^-\to\eta^\prime J/\psi$ for energies between 4.178 and 4.6 GeV measured by the BESIII collaboration. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples. Source code: BESIII_2020_I1762922.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' J/psi
10 class BESIII_2020_I1762922 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2020_I1762922);
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()) MSG_ERROR("Beam energy incompatible with analysis.");
33 }
34
35 void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
36 for (const Particle &child : p.children()) {
37 if (child.children().empty()) {
38 --nRes[child.pid()];
39 --ncount;
40 }
41 else {
42 findChildren(child,nRes,ncount);
43 }
44 }
45 }
46
47 /// Perform the per-event analysis
48 void analyze(const Event& event) {
49 const FinalState& fs = apply<FinalState>(event, "FS");
50 map<long,int> nCount;
51 int ntotal(0);
52 for (const Particle& p : fs.particles()) {
53 nCount[p.pid()] += 1;
54 ++ntotal;
55 }
56 const FinalState& ufs = apply<FinalState>(event, "UFS");
57 for (const Particle& p : ufs.particles(Cuts::pid==443)) {
58 if(p.children().empty()) continue;
59 map<long,int> nRes = nCount;
60 int ncount = ntotal;
61 findChildren(p,nRes,ncount);
62 bool matched=false;
63 for (const Particle& p2 : ufs.particles(Cuts::pid==331)) {
64 if (p2.children().empty()) continue;
65 bool psiParent=false;
66 Particle parent=p2;
67 while (!parent.parents().empty()) {
68 parent=parent.parents()[0];
69 if (parent.pid()==443) {
70 psiParent=true;
71 break;
72 }
73 }
74 if (psiParent) continue;
75 map<long,int> nRes2 = nRes;
76 int ncount2 = ncount;
77 findChildren(p2,nRes2,ncount2);
78 if (ncount2!=0) continue;
79 matched = true;
80 for (const auto& val : nRes2) {
81 if (val.second!=0) {
82 matched = false;
83 break;
84 }
85 }
86 if(matched) {
87 _nJPsi->fill(_ecms);
88 break;
89 }
90 }
91 }
92 }
93
94
95 /// Normalise histograms etc., after the run
96 void finalize() {
97 scale(_nJPsi, crossSection()/ sumOfWeights() /picobarn);
98 }
99
100 /// @}
101
102
103 /// @name Histograms
104 /// @{
105 BinnedHistoPtr<string> _nJPsi;
106 string _ecms;
107 /// @}
108
109 };
110
111
112
113 RIVET_DECLARE_PLUGIN(BESIII_2020_I1762922);
114
115}
|