Rivet analyses referenceBESIII_2022_I2133889Cross section for $e^+e^-\to\omega\pi^+\pi^-$ between 2 and 3.08 GeVExperiment: BESIII (BEPC) Inspire ID: 2133889 Status: VALIDATED NOHEPDATA Authors:
Beam energies: (1.0, 1.0); (1.0, 1.0); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.2, 1.2); (1.2, 1.2); (1.2, 1.2); (1.3, 1.3); (1.3, 1.3); (1.4, 1.4); (1.5, 1.5); (1.5, 1.5); (1.5, 1.5); (1.5, 1.5); (1.5, 1.5) GeV Run details:
Measurement of the cross section for $e^+e^-\to\omega\pi^+\pi^-$ between 2 and 3.08 GeV by the BESIII collaboration. The cross section for a number of resonant intermediate states are also measured. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples. Source code: BESIII_2022_I2133889.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- -> omega pi+ pi-
10 class BESIII_2022_I2133889 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2022_I2133889);
15
16
17 /// @name Analysis methods
18 /// @{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22 // Initialise and register projections
23 declare(FinalState(), "FS");
24 declare(UnstableParticles(), "UFS");
25 book(_sigma[0], 1, 1, 1);
26 for (unsigned int ix=1; ix<7; ++ix) {
27 book(_sigma[ix], 2, 1, ix);
28 if (ix < 3) {
29 for (const string& en : _sigma[ix-1].binning().edges<0>()) {
30 const double end = std::stod(en)*GeV;
31 if (isCompatibleWithSqrtS(end)) {
32 _ecms[ix-1] = en;
33 break;
34 }
35 }
36 }
37 }
38 if (_ecms[0].empty() && _ecms[1].empty()) {
39 MSG_ERROR("Beam energy incompatible with analysis.");
40 }
41 }
42
43 void findChildren(const Particle& p,map<long,int>& nRes, int &ncount) {
44 for (const Particle &child : p.children()) {
45 if (child.children().empty()) {
46 --nRes[child.pid()];
47 --ncount;
48 }
49 else {
50 findChildren(child,nRes,ncount);
51 }
52 }
53 }
54
55 /// Perform the per-event analysis
56 void analyze(const Event& event) {
57 const FinalState& fs = apply<FinalState>(event, "FS");
58 map<long,int> nCount;
59 int ntotal(0);
60 for (const Particle& p : fs.particles()) {
61 nCount[p.pid()] += 1;
62 ++ntotal;
63 }
64 const FinalState& ufs = apply<FinalState>(event, "UFS");
65 bool hasOmegaPiPi=false, hasResonance=false;
66 for (const Particle& p : ufs.particles(Cuts::pid==223)) {
67 if (p.children().empty()) continue;
68 map<long,int> nRes = nCount;
69 int ncount = ntotal;
70 findChildren(p,nRes,ncount);
71 // first the omega pi pi final state
72 if (ncount==2) {
73 hasOmegaPiPi=true;
74 for (const auto& val : nRes) {
75 if (abs(val.first)==211) {
76 if (val.second !=1) {
77 hasOmegaPiPi = false;
78 break;
79 }
80 }
81 else if(val.second!=0) {
82 hasOmegaPiPi = false;
83 break;
84 }
85 }
86 if (hasOmegaPiPi) _sigma[0]->fill(_ecms[0]);
87 }
88 // now omega + second resonance
89 for (const Particle& p2 : ufs.particles(Cuts::pid==9000221||
90 Cuts::pid==9010221||
91 Cuts::pid==10221||
92 Cuts::pid==225)) {
93 if (p2.children().empty()) continue;
94 map<long,int> nRes2 = nRes;
95 int ncount2 = ncount;
96 findChildren(p2,nRes2,ncount2);
97 hasResonance=true;
98 if (ncount2!=0) continue;
99 for (const auto& val : nRes2) {
100 if (val.second!=0) {
101 hasResonance = false;
102 break;
103 }
104 }
105 if (hasResonance) {
106 if (p2.pid()==9000221 ) _sigma[1]->fill(_ecms[1]);
107 else if (p2.pid()==9010221 ) _sigma[2]->fill(_ecms[1]);
108 else if (p2.pid()==10221 ) _sigma[3]->fill(_ecms[1]);
109 else if (p2.pid()==225 ) _sigma[4]->fill(_ecms[1]);
110 break;
111 }
112 }
113 if (hasOmegaPiPi) break;
114 }
115 if (hasResonance) return;
116 // b_1 pi
117 for (const Particle& p : ufs.particles(Cuts::abspid==10213)) {
118 if (p.children().empty()) continue;
119 map<long,int> nRes = nCount;
120 int ncount = ntotal;
121 findChildren(p,nRes,ncount);
122 if(ncount!=1) continue;
123 int ipi = -p.pid()/p.abspid()*211;
124 hasResonance=true;
125 for (const auto& val : nRes) {
126 if (val.first==ipi) {
127 if (val.second !=1) {
128 hasOmegaPiPi = false;
129 break;
130 }
131 }
132 else if(val.second!=0) {
133 hasResonance = false;
134 break;
135 }
136 }
137 if (hasResonance) {
138 _sigma[5]->fill(_ecms[1]);
139 break;
140 }
141 }
142 if (hasOmegaPiPi && !hasResonance) _sigma[6]->fill(_ecms[1]);
143 }
144
145
146 /// Normalise histograms etc., after the run
147 void finalize() {
148 scale(_sigma, crossSection()/ sumOfWeights() /picobarn);
149 }
150
151 /// @}
152
153
154 /// @name Histograms
155 /// @{
156 BinnedHistoPtr<string> _sigma[7];
157 string _ecms[2];
158 /// @}
159
160
161 };
162
163
164 RIVET_DECLARE_PLUGIN(BESIII_2022_I2133889);
165
166}
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