Rivet analyses referenceCMD3_2019_I1720610Cross section for $e^+e^-\to3(\pi^+\pi^-)\pi^0$ below 2 GeV by CMD3Experiment: CMD3 (VEPP-2M) Inspire ID: 1720610 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of the cross section for $e^+e^-\to3(\pi^+\pi^-)\pi^0$, and the resonant sub-processes $2(\pi^+\pi^-)\omega$ and $2(\pi^+\pi^-)\eta$, for energies below 2 GeV by the CMD3 experiment Source code: CMD3_2019_I1720610.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- -> 3(pi+pi-)pi0
10 class CMD3_2019_I1720610 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(CMD3_2019_I1720610);
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(Cuts::pid==221 || Cuts::pid==223), "UFS");
26
27 // Book histograms
28 book(_sigma[0], "TMP/c_all", refData(1, 1, 1));
29 book(_sigma[1], "TMP/c_eta", refData(1, 1, 2));
30 book(_sigma[2], "TMP/c_omega", refData(1, 1, 3));
31
32 }
33
34 void findChildren(const Particle& p, map<long,int>& nRes, int& ncount) {
35 for (const Particle& child : p.children()) {
36 if (child.children().empty()) {
37 --nRes[child.pid()];
38 --ncount;
39 }
40 else {
41 findChildren(child,nRes,ncount);
42 }
43 }
44 }
45
46 /// Perform the per-event analysis
47 void analyze(const Event& event) {
48 // find the final-state particles
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 if (ntotal==7 && nCount[211]==3 && nCount[-211]==3 && nCount[111] ==1 ) {
57 _sigma[0]->fill(sqrtS()/MeV);
58 }
59 // find omega/phi + eta
60 const FinalState& ufs = apply<FinalState>(event, "UFS");
61 bool found=false;
62 for (const Particle& p : ufs.particles()) {
63 if(p.children().empty()) continue;
64 map<long,int> nRes = nCount;
65 int ncount = ntotal;
66 findChildren(p,nRes,ncount);
67 // eta/omega 2(pi+pi-)
68 if(ncount==4) {
69 bool matched = true;
70 for (const auto& val : nRes) {
71 if (abs(val.first)==211 ) {
72 if (val.second !=2) {
73 matched = false;
74 break;
75 }
76 }
77 else if(val.second!=0) {
78 matched = false;
79 break;
80 }
81 }
82 if (matched) {
83 if (p.pid()==221) {
84 _sigma[1]->fill(sqrtS()/MeV);
85 }
86 else if (p.pid()==223) {
87 _sigma[2]->fill(sqrtS()/MeV);
88 }
89 found = true;
90 break;
91 }
92 }
93 if (found) break;
94 }
95
96 }
97
98
99 /// Normalise histograms etc., after the run
100 void finalize() {
101 const double fact = crossSection()/nanobarn/sumOfWeights();
102 for(unsigned int ix=0;ix<3;++ix) {
103 scale(_sigma[ix], fact);
104 Estimate1DPtr tmp;
105 book(tmp,1,1,1+ix);
106 barchart(_sigma[ix],tmp);
107 }
108 }
109
110 /// @}
111
112
113 /// @name Histograms
114 /// @{
115 Histo1DPtr _sigma[3];
116 /// @}
117
118
119 };
120
121
122 RIVET_DECLARE_PLUGIN(CMD3_2019_I1720610);
123
124
125}
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