Rivet analyses

Cross section for e+e KS0KL0between2.00 and 3.08 GeV

Experiment: BESIII (BEPC)

Inspire ID: 1866051

Status: VALIDATED

Authors: - Peter Richardson

References: - arXiv: 2105.13597

Beams: e+ e-

Beam energies: (1.0, 1.0); (1.0, 1.0); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.1, 1.1); (1.2, 1.2); (1.2, 1.2); (1.2, 1.2); (1.3, 1.3); (1.3, 1.3); (1.4, 1.4); (1.5, 1.5)GeV

Run details: - e+e- to hadrons

Measurement of the cross section for e+e KS0KL0 for energies between 2.00 and 3.08 GeV.

Source code:BESIII_2021_I1866051.cc

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"

namespace Rivet {


  /// @brief e+e- > K0K0
  class BESIII_2021_I1866051 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2021_I1866051);


    /// @name Analysis methods
    ///@{

    /// Book histograms and initialise projections before the run
    void init() {

      // Initialise and register projections
      declare(FinalState(), "FS");

      // Book histograms
      book(_nKSKL, 1, 1, 1);
      for (const string& en : _nKSKL.binning().edges<0>()) {
        const double end = stod(en)*GeV;
        if (isCompatibleWithSqrtS(end)) {
          _sqs = en; break;
        }
      }
      raiseBeamErrorIf(_sqs.empty());
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const FinalState& fs = apply<FinalState>(event, "FS");

      map<long,int> nCount;
      int ntotal(0);
      for (const Particle& p : fs.particles()) {
        nCount[p.pid()] += 1;
        ++ntotal;
      }

      if (ntotal==2 && nCount[130]==1 && nCount[310]==1) {
        _nKSKL->fill(_sqs);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_nKSKL, crossSection()/ sumOfWeights() /picobarn);
    }

    ///@}


    /// @name Histograms
    ///@{
    BinnedHistoPtr<string> _nKSKL;
    string _sqs = "";
    ///@}


  };


  RIVET_DECLARE_PLUGIN(BESIII_2021_I1866051);

}