Rivet analyses referenceCMD3_2019_I1740541Cross section for $e^+e^-\to\phi\eta$ for energies below 2 GeVExperiment: CMD3 (VEPP-2M) Inspire ID: 1740541 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of the cross section for $e^+e^-\to K^+K^-\eta$, which is found to be saturated by the resonant $\phi\eta$ sub-process, and therefore only the cross section for $e^+e^-\to\phi\eta$ for energies below 2 GeV is extracted by the CMD3 experiment Source code: CMD3_2019_I1740541.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 phi eta cross section
10 class CMD3_2019_I1740541 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(CMD3_2019_I1740541);
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(_c_phi, "/TMP/phi");
27 }
28
29 void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
30 for(const Particle &child : p.children()) {
31 if(child.children().empty()) {
32 --nRes[child.pid()];
33 --ncount;
34 }
35 else
36 findChildren(child,nRes,ncount);
37 }
38 }
39
40 /// Perform the per-event analysis
41 void analyze(const Event& event) {
42
43 const FinalState& fs = apply<FinalState>(event, "FS");
44
45 map<long,int> nCount;
46 int ntotal(0);
47 for (const Particle& p : fs.particles()) {
48 nCount[p.pid()] += 1;
49 ++ntotal;
50 }
51 const FinalState& ufs = apply<FinalState>(event, "UFS");
52 for (const Particle& p : ufs.particles(Cuts::pid==221)) {
53 if(p.children().empty()) continue;
54 map<long,int> nRes = nCount;
55 int ncount = ntotal;
56 findChildren(p,nRes,ncount);
57 bool matched = false;
58 for (const Particle& p2 : ufs.particles(Cuts::pid==333)) {
59 map<long,int> nResB = nRes;
60 int ncountB = ncount;
61 findChildren(p2,nResB,ncountB);
62 if(ncountB!=0) continue;
63 bool matched = true;
64 for(auto const & val : nResB) {
65 if(val.second!=0) {
66 matched = false;
67 break;
68 }
69 }
70 if(matched) {
71 _c_phi->fill();
72 break;
73 }
74 }
75 if(matched) break;
76 }
77 }
78
79
80 /// Normalise histograms etc., after the run
81 void finalize() {
82 double fact = crossSection()/nanobarn/sumOfWeights();
83 double sigma = _c_phi->val()*fact;
84 double error = _c_phi->err()*fact;
85 for(unsigned int ix=1;ix<4;++ix) {
86 Estimate1DPtr mult;
87 book(mult, ix, 1, 6);
88 for (auto& b : mult->bins()) {
89 if (inRange(sqrtS()/GeV, b.xMin(), b.xMax())) {
90 b.set(sigma, error);
91 }
92 }
93 }
94 }
95
96 /// @}
97
98
99 /// @name Histograms
100 /// @{
101 CounterPtr _c_phi;
102 /// @}
103
104
105 };
106
107
108 RIVET_DECLARE_PLUGIN(CMD3_2019_I1740541);
109
110
111}
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