Rivet analyses referenceCMD3_2019_I1744510Cross section for $e^+e^-\to\eta\pi^+\pi^-$ between 1.08 and 2 GeVExperiment: CMD3 (VEPP-2M) Inspire ID: 1744510 Status: UNVALIDATED Authors:
Beam energies: ANY Run details:
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_I1744510 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(CMD3_2019_I1744510);
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(_numEtaPiPi,"TMP/EtaPiPi");
27
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 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()) {
53 if(p.children().empty()) continue;
54 // find the omega
55 if(p.pid()==221) {
56 map<long,int> nRes = nCount;
57 int ncount = ntotal;
58 findChildren(p,nRes,ncount);
59 // eta pi+pi-
60 if(ncount!=2) continue;
61 bool matched = true;
62 for(auto const & val : nRes) {
63 if(abs(val.first)==211) {
64 if(val.second !=1) {
65 matched = false;
66 break;
67 }
68 }
69 else if(val.second!=0) {
70 matched = false;
71 break;
72 }
73 }
74 if(matched)
75 _numEtaPiPi->fill();
76 }
77 }
78 }
79
80
81 /// Normalise histograms etc., after the run
82 void finalize() {
83 double sigma = _numEtaPiPi->val();
84 double error = _numEtaPiPi->err();
85 sigma *= crossSection()/ sumOfWeights() /nanobarn;
86 error *= crossSection()/ sumOfWeights() /nanobarn;
87 Scatter2D temphisto(refData(2, 1, 1));
88 Scatter2DPtr mult;
89 book(mult, 2, 1, 1);
90 for (size_t b = 0; b < temphisto.numPoints(); b++) {
91 const double x = temphisto.point(b).x();
92 pair<double,double> ex = temphisto.point(b).xErrs();
93 pair<double,double> ex2 = ex;
94 if(ex2.first ==0.) ex2. first=0.0001;
95 if(ex2.second==0.) ex2.second=0.0001;
96 if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
97 mult->addPoint(x, sigma, ex, make_pair(error,error));
98 }
99 else {
100 mult->addPoint(x, 0., ex, make_pair(0.,.0));
101 }
102 }
103 }
104
105 //@}
106
107
108 /// @name Histograms
109 //@{
110 CounterPtr _numEtaPiPi;
111 //@}
112
113
114 };
115
116
117 // The hook for the plugin system
118 RIVET_DECLARE_PLUGIN(CMD3_2019_I1744510);
119
120
121}
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