Rivet analyses referenceBABAR_2007_I760730Cross section for $e^+e^-\to\Lambda\bar{\Lambda}$, $\Sigma^0\bar{\Sigma}^0$ and $\Lambda\bar{\Sigma}^0$ between threshold and 3 GeVExperiment: BABAR (PEP-II) Inspire ID: 760730 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of the cross section for $e^+e^-\to\Lambda\bar{\Lambda}$ between threshold and 3 GeV. Source code: BABAR_2007_I760730.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- > hyperons
10 class BABAR_2007_I760730 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2007_I760730);
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(_nLL, "/TMP/nLL" );
26 book(_nSS, "/TMP/nSS" );
27 book(_nLS, "/TMP/nLS" );
28 }
29
30 void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
31 for(const Particle &child : p.children()) {
32 if(child.children().empty()) {
33 nRes[child.pid()]-=1;
34 --ncount;
35 }
36 else
37 findChildren(child,nRes,ncount);
38 }
39 }
40
41 /// Perform the per-event analysis
42 void analyze(const Event& event) {
43 const FinalState& fs = apply<FinalState>(event, "FS");
44 // total hadronic and muonic cross sections
45 map<long,int> nCount;
46 int ntotal(0);
47 for (const Particle& p : fs.particles()) {
48 nCount[p.pid()] += 1;
49 ++ntotal;
50 }
51
52 // find the Lambdas and Sigmas
53 const FinalState& ufs = apply<UnstableParticles>(event, "UFS");
54 for(unsigned int ix=0;ix<ufs.particles().size();++ix) {
55 const Particle& p1 = ufs.particles()[ix];
56 if(abs(p1.pid())!=3122&&abs(p1.pid())!=3212) continue;
57 bool matched = false;
58 // check fs
59 bool fs = true;
60 for(const Particle & child : p1.children()) {
61 if(child.pid()==p1.pid()) {
62 fs = false;
63 break;
64 }
65 }
66 if(!fs) continue;
67 // find the children
68 map<long,int> nRes = nCount;
69 int ncount = ntotal;
70 findChildren(p1,nRes,ncount);
71 for(unsigned int iy=ix+1;iy<ufs.particles().size();++iy) {
72 const Particle& p2 = ufs.particles()[iy];
73 if(abs(p2.pid())!=3122&&abs(p2.pid())!=3212) continue;
74 // check fs
75 bool fs = true;
76 for(const Particle & child : p2.children()) {
77 if(child.pid()==p2.pid()) {
78 fs = false;
79 break;
80 }
81 }
82 if(!fs) continue;
83 map<long,int> nRes2 = nRes;
84 int ncount2 = ncount;
85 findChildren(p2,nRes2,ncount2);
86 if(ncount2!=0) continue;
87 matched=true;
88 for(auto const & val : nRes2) {
89 if(val.second!=0) {
90 matched = false;
91 break;
92 }
93 }
94 if(matched) {
95 if(abs(p1.pid())==3122 && abs(p2.pid())==3122)
96 _nLL->fill();
97 else if(abs(p1.pid())==3212 && abs(p2.pid())==3212)
98 _nSS->fill();
99 else
100 _nLS->fill();
101 break;
102 }
103 }
104 if(matched) break;
105 }
106 }
107
108 /// Normalise histograms etc., after the run
109 void finalize() {
110 double fact = crossSection()/ sumOfWeights() /picobarn;
111 for(unsigned int ix=1;ix<4;++ix) {
112 double sigma,error;
113 if(ix==1) {
114 sigma = _nLL->val()*fact;
115 error = _nLL->err()*fact;
116 }
117 else if(ix==2) {
118 sigma = _nSS->val()*fact;
119 error = _nSS->err()*fact;
120 }
121 else {
122 sigma = _nLS->val()*fact;
123 error = _nLS->err()*fact;
124 }
125 Estimate1DPtr mult;
126 book(mult, ix, 1, 1);
127 for (auto& b : mult->bins()) {
128 if (inRange(sqrtS()/GeV, b.xMin(), b.xMax())) {
129 b.set(sigma, error);
130 }
131 }
132 }
133 }
134
135 /// @}
136
137
138 /// @name Histograms
139 /// @{
140 CounterPtr _nLL,_nSS,_nLS;
141 /// @}
142
143
144 };
145
146
147 RIVET_DECLARE_PLUGIN(BABAR_2007_I760730);
148
149
150}
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