Rivet analyses referenceBESIII_2021_I1866051Cross section for $e^+e^-\to$ $K_S^0K_L^0$between2.00 and 3.08 GeVExperiment: BESIII (BEPC) Inspire ID: 1866051 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of the cross section for $e^+e^-\to$ $K_S^0K_L^0$ for energies between 2.00 and 3.08 GeV Source code: BESIII_2021_I1866051.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4
5namespace Rivet {
6
7
8 /// @brief e+e- > K0K0
9 class BESIII_2021_I1866051 : public Analysis {
10 public:
11
12 /// Constructor
13 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2021_I1866051);
14
15
16 /// @name Analysis methods
17 ///@{
18
19 /// Book histograms and initialise projections before the run
20 void init() {
21
22 // Initialise and register projections
23 declare(FinalState(), "FS");
24
25 // Book histograms
26 book(_nKSKL , "TMP/nKSKL");
27 }
28
29
30 /// Perform the per-event analysis
31 void analyze(const Event& event) {
32 const FinalState& fs = apply<FinalState>(event, "FS");
33
34 map<long,int> nCount;
35 int ntotal(0);
36 for (const Particle& p : fs.particles()) {
37 nCount[p.pid()] += 1;
38 ++ntotal;
39 }
40
41 if(ntotal==2 && nCount[130]==1 && nCount[310]==1)
42 _nKSKL->fill();
43 }
44
45
46 /// Normalise histograms etc., after the run
47 void finalize() {
48 double sigma = _nKSKL->val()*crossSection()/ sumOfWeights() /picobarn;
49 double error = _nKSKL->err()*crossSection()/ sumOfWeights() /picobarn;
50 Scatter2D temphisto(refData(1, 1, 1));
51 Scatter2DPtr mult;
52 book(mult, 1, 1, 1);
53 for (size_t b = 0; b < temphisto.numPoints(); b++) {
54 const double x = temphisto.point(b).x();
55 pair<double,double> ex = temphisto.point(b).xErrs();
56 pair<double,double> ex2 = ex;
57 if(ex2.first ==0.) ex2. first=0.0001;
58 if(ex2.second==0.) ex2.second=0.0001;
59 if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
60 mult->addPoint(x, sigma, ex, make_pair(error,error));
61 }
62 else {
63 mult->addPoint(x, 0., ex, make_pair(0.,.0));
64 }
65 }
66 }
67
68 ///@}
69
70
71 /// @name Histograms
72 ///@{
73 CounterPtr _nKSKL;
74 ///@}
75
76
77 };
78
79
80 RIVET_DECLARE_PLUGIN(BESIII_2021_I1866051);
81
82}
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