Rivet analyses referenceBESIII_2019_I1756876Cross section for $e^+e^-\to D^+D^-\pi^+\pi^-$ for $E_{\text{CMS}}=4.36\to4.60$ GeVExperiment: BESIII (BEPC) Inspire ID: 1756876 Status: VALIDATED Authors:
Beam energies: (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3) GeV Run details:
Cross section for $e^+e^-\to D^+D^-\pi^+\pi^-$ for $E_{\text{CMS}}=4.36\to4.60$ GeV. The cross sections for the subprocesses $e^+e^-\to D_1(2420)^\pm D^\mp$ and $e^+e^-\to \psi(3770) \pi^+\pi^-$ are measured. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples. Source code: BESIII_2019_I1756876.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 Cross section for D+D- pi+ pi- (D1 D and psi(3770) pi+pi- subprocesses)
10 class BESIII_2019_I1756876 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2019_I1756876);
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 histograms
26 book(_nD1D, 1, 1, 1);
27 book(_nPsi, 1, 1, 2);
28 for (const string& en : _nD1D.binning().edges<0>()) {
29 const double end = std::stod(en)*MeV;
30 if (isCompatibleWithSqrtS(end)) {
31 _ecms = en;
32 break;
33 }
34 }
35 if (_ecms.empty()) MSG_ERROR("Beam energy incompatible with analysis.");
36
37 }
38
39 void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
40 for(const Particle &child : p.children()) {
41 if(child.children().empty()) {
42 nRes[child.pid()]-=1;
43 --ncount;
44 }
45 else
46 findChildren(child,nRes,ncount);
47 }
48 }
49
50 /// Perform the per-event analysis
51 void analyze(const Event& event) {
52 const FinalState& fs = apply<FinalState>(event, "FS");
53
54 map<long,int> nCount;
55 int ntotal(0);
56 for (const Particle& p : fs.particles()) {
57 nCount[p.pid()] += 1;
58 ++ntotal;
59 }
60 const FinalState& ufs = apply<FinalState>(event, "UFS");
61 bool matched=false;
62 for(const Particle& p1 : ufs.particles(Cuts::abspid==411)) {
63 int sign = p1.pid()/411;
64 map<long,int> nRes = nCount;
65 int ncount = ntotal;
66 findChildren(p1,nRes,ncount);
67 matched=false;
68 for(const Particle& p2 : ufs.particles(Cuts::pid==-sign*411)) {
69 map<long,int> nRes2 = nRes;
70 int ncount2 = ncount;
71 findChildren(p2,nRes2,ncount2);
72 if(ncount2!=2) continue;
73 matched=true;
74 for(auto const & val : nRes2) {
75 if(abs(val.first)==211) {
76 if(val.second!=1) {
77 matched = false;
78 break;
79 }
80 }
81 else if(val.second!=0) {
82 matched = false;
83 break;
84 }
85 }
86 if(matched) break;
87 }
88 if(matched)
89 break;
90 }
91 if(!matched) vetoEvent;
92 // psi(3770) pi+pi-
93 for(const Particle& p1 : ufs.particles(Cuts::abspid==30443)) {
94 if(p1.children().empty()) continue;
95 map<long,int> nRes = nCount;
96 int ncount = ntotal;
97 findChildren(p1,nRes,ncount);
98 // psi(3770) pi+pi-
99 if(ncount!=2) continue;
100 bool matched = true;
101 for(auto const & val : nRes) {
102 if(abs(val.first)==211) {
103 if(val.second !=1) {
104 matched = false;
105 break;
106 }
107 }
108 else if(val.second!=0) {
109 matched = false;
110 break;
111 }
112 }
113 if(matched) {
114 _nPsi->fill(_ecms);
115 return;
116 }
117 }
118 // D1 D
119 for(const Particle& p1 : ufs.particles(Cuts::abspid==10413)) {
120 if(p1.children().empty()) continue;
121 int sign = p1.pid()/10413;
122 map<long,int> nRes = nCount;
123 int ncount = ntotal;
124 findChildren(p1,nRes,ncount);
125 matched=false;
126 for(const Particle& p2 : ufs.particles(Cuts::pid==-sign*411)) {
127 map<long,int> nRes2 = nRes;
128 int ncount2 = ncount;
129 findChildren(p2,nRes2,ncount2);
130 if(ncount2!=0) continue;
131 matched=true;
132 for(auto const & val : nRes2) {
133 if(val.second!=0) {
134 matched = false;
135 break;
136 }
137 }
138 if(matched) break;
139 }
140 if(matched) {
141 _nD1D->fill(_ecms);
142 return;
143 }
144 }
145 }
146
147 /// Normalise histograms etc., after the run
148 void finalize() {
149 double fact = crossSection()/ sumOfWeights()/picobarn;
150 scale(_nD1D,fact);
151 scale(_nPsi,fact);
152 }
153
154 /// @}
155
156 /// @name Histograms
157 /// @{
158 BinnedHistoPtr<string> _nD1D, _nPsi;
159 string _ecms;
160 /// @}
161
162 };
163
164
165 RIVET_DECLARE_PLUGIN(BESIII_2019_I1756876);
166
167}
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