Rivet analyses referenceCMD2_2005_I658856Cross section for $e^+e^-\to\pi\gamma$ and $\eta\gamma$ for energies between 600 MeV and 1380 MeVExperiment: CMD2 (VEPP-2M) Inspire ID: 658856 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Cross section for $e^+e^-\to\pi\gamma$ and $\eta\gamma$ for energies between 600 MeV and 1380 MeV Source code: CMD2_2005_I658856.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 CMD2_2005_I658856 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(CMD2_2005_I658856);
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(_numEtaGamma, "TMP/EtaGamma");
27 book(_numPi0Gamma, "TMP/Pi0Gamma");
28 }
29
30 void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
31 for (const Particle &child : p.children()) {
32 if(child.children().empty()) {
33 --nRes[child.pid()];
34 --ncount;
35 }
36 else
37 findChildren(child,nRes,ncount);
38 }
39 }
40
41 /// Perform the per-event analysis
42 void analyze(const Event& event) {
43
44 const FinalState& fs = apply<FinalState>(event, "FS");
45
46 map<long,int> nCount;
47 int ntotal(0);
48 for (const Particle& p : fs.particles()) {
49 nCount[p.pid()] += 1;
50 ++ntotal;
51 }
52 if(ntotal==2 && nCount[22]==1 && nCount[111]==1)
53 _numPi0Gamma->fill();
54
55
56 const FinalState& ufs = apply<FinalState>(event, "UFS");
57 for (const Particle& p : ufs.particles()) {
58 if(p.children().empty()) continue;
59 // find the omega
60 if(p.pid()==221) {
61 map<long,int> nRes = nCount;
62 int ncount = ntotal;
63 findChildren(p,nRes,ncount);
64 // eta pi+pi-
65 if(ncount!=1) continue;
66 bool matched = true;
67 for(auto const & val : nRes) {
68 if(val.first==22) {
69 if(val.second !=1) {
70 matched = false;
71 break;
72 }
73 }
74 else if(val.second!=0) {
75 matched = false;
76 break;
77 }
78 }
79 if(matched)
80 _numEtaGamma->fill();
81 }
82 }
83
84 }
85
86
87 /// Normalise histograms etc., after the run
88 void finalize() {
89
90 for (unsigned int ix=1;ix<3;++ix) {
91 double sigma,error;
92 if(ix==1) {
93 sigma = _numEtaGamma->val();
94 error = _numEtaGamma->err();
95 }
96 else {
97 sigma = _numPi0Gamma->val();
98 error = _numPi0Gamma->err();
99 }
100 sigma *= crossSection()/ sumOfWeights() /nanobarn;
101 error *= crossSection()/ sumOfWeights() /nanobarn;
102 Estimate1DPtr mult;
103 book(mult, ix, 1, 1);
104 for (auto& b : mult->bins()) {
105 if (inRange(sqrtS()/MeV, b.xMin(), b.xMax())) {
106 b.set(sigma, error);
107 }
108 }
109 }
110 }
111
112 /// @}
113
114
115 /// @name Histograms
116 /// @{
117 CounterPtr _numEtaGamma,_numPi0Gamma;
118 /// @}
119
120
121 };
122
123
124 RIVET_DECLARE_PLUGIN(CMD2_2005_I658856);
125
126
127}
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