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 Add a short analysis description here
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(), "UFS");
26
27 // Book histograms
28
29 book(_c_all , "/TMP/all");
30 book(_c_omega, "/TMP/omega");
31 book(_c_eta , "/TMP/eta");
32
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 /// 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 _c_all->fill();
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 // find the eta/omega
65 if(p.pid()!=221 && p.pid()!=223) continue;
66 map<long,int> nRes = nCount;
67 int ncount = ntotal;
68 findChildren(p,nRes,ncount);
69 // eta/omega 2(pi+pi-)
70 if(ncount==4) {
71 bool matched = true;
72 for(auto const & val : nRes) {
73 if(abs(val.first)==211 ) {
74 if(val.second !=2) {
75 matched = false;
76 break;
77 }
78 }
79 else if(val.second!=0) {
80 matched = false;
81 break;
82 }
83 }
84 if(matched) {
85 if(p.pid()==221)
86 _c_eta->fill();
87 else if(p.pid()==223)
88 _c_omega->fill();
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 double fact = crossSection()/nanobarn/sumOfWeights();
102 for (unsigned int ix=1;ix<4;++ix) {
103 double sigma(0.),error(0.);
104 if(ix==1) {
105 sigma = _c_all->val()*fact;
106 error = _c_all->err()*fact;
107 }
108 else if(ix==2) {
109 sigma = _c_eta->val()*fact;
110 error = _c_eta->err()*fact;
111 }
112 else if(ix==3) {
113 sigma = _c_omega->val()*fact;
114 error = _c_omega->err()*fact;
115 }
116 Estimate1DPtr mult;
117 book(mult, 1, 1, ix);
118 for (auto& b : mult->bins()) {
119 if (inRange(sqrtS()/MeV, b.xMin(), b.xMax())) {
120 b.set(sigma, error);
121 }
122 }
123 }
124 }
125
126 /// @}
127
128
129 /// @name Histograms
130 /// @{
131 CounterPtr _c_all,_c_omega,_c_eta;
132 /// @}
133
134
135 };
136
137
138 RIVET_DECLARE_PLUGIN(CMD3_2019_I1720610);
139
140
141}
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