Rivet analyses referenceBESIII_2021_I1849633Cross Section for $e^+e^-\to\eta \psi(2S)$ for energies between 4.236 to 4.600 GeVExperiment: BESIII (BEPC) Inspire ID: 1849633 Status: VALIDATED NOHEPDATA 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); (2.2, 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:
Cross section for $e^+e^-\to\eta \psi(2S)$ for energies between 4.236 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_I1849633.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 psi(2S)
10 class BESIII_2021_I1849633 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2021_I1849633);
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(_sigma, 1, 1, 1);
25
26 for (const string& en : _sigma.binning().edges<0>()) {
27 const double end = std::stod(en)*GeV;
28 if (isCompatibleWithSqrtS(end)) {
29 _ecms = en;
30 break;
31 }
32 }
33 if(_ecms.empty()) 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(Cuts::pid==PID::PSI2S)) {
59 if (p.children().empty()) continue;
60 // find the psi(2s)
61 map<long,int> nRes = nCount;
62 int ncount = ntotal;
63 findChildren(p,nRes,ncount);
64 bool matched=false;
65 for (const Particle& p2 : ufs.particles(Cuts::pid==PID::ETA)) {
66 if (p2.children().empty()) continue;
67 bool psi2SParent=false;
68 Particle parent=p2;
69 while (!parent.parents().empty()) {
70 parent=parent.parents()[0];
71 if (parent.pid()==PID::PSI2S) {
72 psi2SParent=true;
73 break;
74 }
75 }
76 if (psi2SParent) continue;
77 map<long,int> nRes2 = nRes;
78 int ncount2 = ncount;
79 findChildren(p2,nRes2,ncount2);
80 if (ncount2!=0) continue;
81 matched = true;
82 for (const auto& val : nRes2) {
83 if (val.second!=0) {
84 matched = false;
85 break;
86 }
87 }
88 if (matched) {
89 _sigma->fill(_ecms);
90 break;
91 }
92 }
93 if (matched) break;
94 }
95 }
96
97
98 /// Normalise histograms etc., after the run
99 void finalize() {
100 scale(_sigma,crossSection()/ sumOfWeights() /picobarn);
101 }
102
103 /// @}
104
105
106 /// @name Histograms
107 /// @{
108 BinnedHistoPtr<string> _sigma;
109 string _ecms;
110 /// @}
111
112
113 };
114
115
116 RIVET_DECLARE_PLUGIN(BESIII_2021_I1849633);
117
118}
|
