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}