Rivet analyses referenceBELLE_2004_I653673Double charmonium production in $e^+e^-$ collisions at $\sqrt{s}=10.6\,$GeVExperiment: BELLE (KEKB) Inspire ID: 653673 Status: VALIDATED NOHEPDATA Authors:
Beam energies: (5.3, 5.3) GeV Run details:
Double charmonium production at $\sqrt{s}=10.6\,$GeV. The cross sections and $\alpha$ parameters were taken from the tables in the paper and the corrected angular distributions read from the figures. Source code: BELLE_2004_I653673.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- -> double charmonium
10 class BELLE_2004_I653673 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2004_I653673);
15
16
17 /// @name Analysis methods
18 /// @{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22 // projections
23 declare("FS",FinalState());
24 declare("UFS",UnstableParticles(Cuts::pid==443 || Cuts::pid==100443 ||
25 Cuts::pid==441 || Cuts::pid==10441 || Cuts::pid==100441));
26 // histograms
27 for (unsigned int ix=0; ix<3; ++ix) {
28 for (unsigned int iy=0;iy<3;++iy) {
29 book(_p[ix][iy],"TMP/p_"+toString(ix+1)+"_"+toString(iy+1),
30 refData<YODA::BinnedEstimate<string>>(3,1+ix,1+iy));
31 if (ix==2) continue;
32 book(_h_sigma[ix][iy], 1+ix, 1 , 1+2*iy);
33 book(_h_angle[ix][iy], 4 , 1+ix, 1+iy );
34 }
35 }
36 }
37
38 void findChildren(const Particle& p,map<long,int>& nRes, int& ncount,
39 unsigned int & nCharged) {
40 for (const Particle &child : p.children()) {
41 if (child.children().empty()) {
42 --nRes[child.pid()];
43 --ncount;
44 if (PID::isCharged(p.pid())) ++nCharged;
45 }
46 else {
47 findChildren(child,nRes,ncount,nCharged);
48 }
49 }
50 }
51
52 double helicityAngle(const Particle & p) const {
53 if (p.children().size()!=2) return 10.;
54 if (p.children()[0].abspid()!=PID::MUON || p.children()[0].pid()!=-p.children()[1].pid()) {
55 return 10.;
56 }
57 Vector3 axis = p.p3().unit();
58 const LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
59 for (const Particle& child : p.children()) {
60 if (child.pid()!=PID::MUON) continue;
61 return axis.dot(boost.transform(child.momentum()).p3().unit());
62 }
63 return 10;
64 }
65
66
67 /// Perform the per-event analysis
68 void analyze(const Event& event) {
69 // final state particles
70 const FinalState& fs = apply<FinalState>(event, "FS");
71 map<long,int> nCount;
72 int ntotal(0);
73 for (const Particle& p : fs.particles()) {
74 nCount[p.pid()] += 1;
75 ++ntotal;
76 }
77 // loop over J/psi and psi(2S)
78 const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
79 bool matched=false;
80 for (const Particle& p : ufs.particles(Cuts::pid==443 || Cuts::pid==100443 )) {
81 if (p.children().empty()) continue;
82 map<long,int> nRes = nCount;
83 int ncount = ntotal;
84 unsigned int nCharged=0;
85 findChildren(p,nRes,ncount,nCharged);
86 // eta_c, chi_c0, eta_c(2S)
87 for (const Particle& p2 : ufs.particles(Cuts::pid==441 || Cuts::pid==10441 || Cuts::pid==100441)) {
88 map<long,int> nResB = nRes;
89 int ncountB = ncount;
90 unsigned int nChargedB=0;
91 findChildren(p2,nResB,ncountB,nChargedB);
92 if (ncountB!=0) continue;
93 matched = true;
94 for (const auto& val : nResB) {
95 if (val.second!=0) {
96 matched = false;
97 break;
98 }
99 }
100 if (matched) {
101 unsigned int ipsi = p.pid()/100000;
102 unsigned int ieta = p2.pid()/10000;
103 if (ieta>1) ieta=2;
104 // fill the cross sections
105 if ((ipsi==0 && nChargedB>2) || (ipsi==1 && nChargedB>0)) {
106 _h_sigma[ipsi][ieta]->fill(_ecms);
107 }
108 if (ipsi>0) break;
109 // angular dists for J/psi only
110 // production
111 const double cProd = p.p3().z()/p.p3().mod();
112 _h_angle[0][ieta]->fill(abs(cProd));
113 _p[0][ieta]->fill(_ecms,-1.25*(1.-3.*sqr(cProd)));
114 _p[2][ieta]->fill(_ecms,-1.25*(1.-3.*sqr(cProd)));
115 // helicity angle
116 const double cHel = helicityAngle(p);
117 if (cHel>1.) break;
118 _h_angle[1][ieta]->fill(abs(cHel));
119 _p[1][ieta]->fill(_ecms,-1.25*(1.-3.*sqr(cHel)));
120 _p[2][ieta]->fill(_ecms,-1.25*(1.-3.*sqr(cHel)));
121 break;
122 }
123 }
124 if (matched) break;
125 }
126 }
127
128
129 /// Normalise histograms etc., after the run
130 void finalize() {
131 for (unsigned int ix=0; ix<2; ++ix) {
132 scale(_h_sigma[ix], crossSection()/sumOfWeights()/femtobarn);
133 normalize(_h_angle[ix]);
134 }
135 // extract the alpha parameters
136 for (unsigned int ix=0; ix<3; ++ix) {
137 for (unsigned int iy=0; iy<3; ++iy) {
138 const double val = _p[ix][iy]->bin(1).mean(2);
139 const double err = _p[ix][iy]->bin(1).stdErr(2);
140 BinnedEstimatePtr<string> tmp;
141 book(tmp,3,1+ix,1+iy);
142 const double alpha = 3.*val/(1-val);
143 const double error = 3./sqr(1.-val)*err;
144 tmp->bin(1).set(alpha,error);
145 }
146 }
147 }
148
149 /// @}
150
151
152 /// @name Histograms
153 /// @{
154 BinnedHistoPtr<string> _h_sigma[2][3];
155 Histo1DPtr _h_angle[2][3];
156 BinnedProfilePtr<string> _p[3][3];
157 string _ecms="10.6";
158 /// @}
159
160
161 };
162
163
164 RIVET_DECLARE_PLUGIN(BELLE_2004_I653673);
165
166}
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