Rivet analyses referenceBABAR_2021_I1938254Cross sections for e+e−→π+π−4π0 and e+e−→π+π−3π0η between threshold and 4.5 GeVExperiment: BABAR (PEP-II) Inspire ID: 1938254 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Cross sections for e+e−→π+π−4π0 and e+e−→π+π−3π0η between threshold and 4.5 GeV measured by BaBar using radiative return. The contributions of the ηπ+π−π0, ηω, ωπ0π0π0 intermediate states are also measured. Useful to compare hadronization and other non-perturbative models at low energies between 1.4 and 4.5 GeV. Source code: BABAR_2021_I1938254.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- > pi+pi-4pi0 and pi+pi-3pi0 eta
10 class BABAR_2021_I1938254 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2021_I1938254);
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 // Histograms
26 for(unsigned int ix=0;ix<5;++ix) {
27 book(_num[ix],"TMP/num_"+to_string(ix));
28 }
29 }
30
31 void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
32 for( const Particle &child : p.children()) {
33 if(child.children().empty()) {
34 --nRes[child.pid()];
35 --ncount;
36 }
37 else
38 findChildren(child,nRes,ncount);
39 }
40 }
41
42 /// Perform the per-event analysis
43 void analyze(const Event& event) {
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 // stable final state
53 if(nCount[211]==1 && nCount[-211]==1 && nCount[111]==4)
54 _num[0]->fill();
55 // intermediate states
56 const FinalState& ufs = apply<FinalState>(event, "UFS");
57 for (const Particle& p : ufs.particles(Cuts::pid==221 || Cuts::pid==223)) {
58 map<long,int> nRes = nCount;
59 int ncount = ntotal;
60 findChildren(p,nRes,ncount);
61 // eta +X
62 int idOther;
63 if(p.pid()==221) {
64 idOther=223;
65 bool matched = true;
66 for(auto const & val : nRes) {
67 if(abs(val.first)==211 || val.first==-211 ) {
68 if(val.second !=1) {
69 matched = false;
70 break;
71 }
72 }
73 else if(val.first==111) {
74 // 1 or 3 pi0
75 if(val.second !=3 && val.second != 1) {
76 matched = false;
77 break;
78 }
79 }
80 else if(val.second!=0) {
81 matched = false;
82 break;
83 }
84 }
85 if(matched) {
86 if(nRes[111]==1)
87 _num[1]->fill();
88 else
89 _num[4]->fill();
90 }
91
92
93 }
94 // omega+X
95 else {
96 idOther=221;
97 // omega+ 3pi0
98 bool matched = true;
99 for(auto const & val : nRes) {
100 if(abs(val.first)==111) {
101 if(val.second !=3) {
102 matched = false;
103 break;
104 }
105 }
106 else if(val.second!=0) {
107 matched = false;
108 break;
109 }
110 }
111 if(matched) {
112 _num[3]->fill();
113 }
114 }
115 for (const Particle& p2 : ufs.particles(Cuts::pid==idOther)) {
116 map<long,int> nResB = nRes;
117 int ncountB = ncount;
118 findChildren(p2,nResB,ncountB);
119 if(ncountB!=0) continue;
120 bool matched2 = true;
121 for(auto const & val : nResB) {
122 if(val.second!=0) {
123 matched2 = false;
124 break;
125 }
126 }
127 if(matched2) {
128 _num[2]->fill();
129 }
130 }
131 }
132 }
133
134
135 /// Normalise histograms etc., after the run
136 void finalize() {
137 double fact = crossSection()/nanobarn/sumOfWeights();
138 for (unsigned int ix=0;ix<5;++ix) {
139 double sigma = _num[ix]->val()*fact;
140 double error = _num[ix]->err()*fact;
141 Estimate1DPtr mult;
142 book(mult, 1+ix, 1, 1);
143 for (auto& b : mult->bins()) {
144 if (inRange(sqrtS()/GeV, b.xMin(), b.xMax())) {
145 b.set(sigma, error);
146 }
147 }
148 }
149 }
150
151 ///@}
152
153
154 /// @name Histograms
155 ///@{
156 CounterPtr _num[5];
157 ///@}
158
159
160 };
161
162
163 RIVET_DECLARE_PLUGIN(BABAR_2021_I1938254);
164
165}
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