Rivet analyses referenceSND_2019_I1726419Cross section for $e^+e^-\to\pi^+\pi^-\pi^0\eta$ for energies below 2 GeVExperiment: SND (VEPP-2M) Inspire ID: 1726419 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of the cross section for $e^+e^-\to\pi^+\pi^-\pi^0\eta$, and the resonant sub-processes $\omega\eta$, $\phi\eta$ and $a_0(980)\rho$, for energies below 2 GeV by the SND experiment Source code: SND_2019_I1726419.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 SND pi+pi-pi0eta cross section
10 class SND_2019_I1726419 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(SND_2019_I1726419);
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
28 book(_c_all , "/TMP/all");
29 book(_c_omega, "/TMP/omega");
30 book(_c_phi , "/TMP/phi");
31 book(_c_rho , "/TMP/rho");
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
49 const FinalState& fs = apply<FinalState>(event, "FS");
50
51 map<long,int> nCount;
52 int ntotal(0);
53 for (const Particle& p : fs.particles()) {
54 nCount[p.pid()] += 1;
55 ++ntotal;
56 }
57 const FinalState& ufs = apply<FinalState>(event, "UFS");
58 bool found = false, foundOmegaPhi = false;
59 for (const Particle& p : ufs.particles(Cuts::pid==221)) {
60 map<long,int> nRes = nCount;
61 int ncount = ntotal;
62 findChildren(p,nRes,ncount);
63 // eta pi+pi-
64 if(ncount==3) {
65 bool matched = true;
66 for(auto const & val : nRes) {
67 if(abs(val.first)==211 || val.first==111 ) {
68 if(val.second !=1) {
69 matched = false;
70 break;
71 }
72 }
73 else if(val.second!=0) {
74 matched = false;
75 break;
76 }
77 }
78 if(matched) {
79 _c_all->fill();
80 found = true;
81 }
82 }
83 for (const Particle& p2 : ufs.particles()) {
84 if(p2.pid()!=223 && p2.pid()!=333) continue;
85 map<long,int> nResB = nRes;
86 int ncountB = ncount;
87 findChildren(p2,nResB,ncountB);
88 if(ncountB!=0) continue;
89 bool matched2 = true;
90 for(auto const & val : nResB) {
91 if(val.second!=0) {
92 matched2 = false;
93 break;
94 }
95 }
96 if(matched2) {
97 if(p2.pid()==223)
98 _c_omega->fill();
99 else if(p2.pid()==333)
100 _c_phi->fill();
101 foundOmegaPhi=true;
102 }
103 }
104 }
105 if(found && !foundOmegaPhi)
106 _c_rho->fill();
107 }
108
109
110 /// Normalise histograms etc., after the run
111 void finalize() {
112 double fact = crossSection()/nanobarn/sumOfWeights();
113 for (unsigned int ix=1;ix<5;++ix) {
114 double sigma(0.),error(0.);
115 if(ix==1) {
116 sigma = _c_all->val()*fact;
117 error = _c_all->err()*fact;
118 }
119 else if(ix==2) {
120 sigma = _c_omega->val()*fact;
121 error = _c_omega->err()*fact;
122 }
123 else if(ix==3) {
124 sigma = _c_phi->val()*fact;
125 error = _c_phi->err()*fact;
126 }
127 else if(ix==4) {
128 sigma = _c_rho->val()*fact;
129 error = _c_rho->err()*fact;
130 }
131 Estimate1DPtr mult;
132 book(mult, 1, 1, ix);
133 for (auto& b : mult->bins()) {
134 if (inRange(sqrtS()/GeV, b.xMin(), b.xMax())) {
135 b.set(sigma, error);
136 }
137 }
138 }
139 }
140
141 /// @}
142
143
144 /// @name Histograms
145 /// @{
146 CounterPtr _c_all, _c_omega, _c_phi,_c_rho;
147 /// @}
148
149
150 };
151
152
153 RIVET_DECLARE_PLUGIN(SND_2019_I1726419);
154
155
156}
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