Rivet analyses

Cross section for e+e− → KS0KL0 for $\sqrt{s}$ between 3.51 GeV and 4.95 GeV

Experiment: BESIII (BEPC)

Inspire ID: 2738509

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 132 (2024) 13, 131901 - arXiv: 2312.10962

Beams: e+ e-

Beam energies: ANY

Run details: - e+e- to hadrons K0S and K0L stable

Cross section for e+e− → KS0KL0 for $\sqrt{s}$ between 3.51 GeV and 4.95 GeV measured by BES

Source code:BESIII_2024_I2738509.cc

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

namespace Rivet {


  /// @brief e+ e- > KS0 KL0
  class BESIII_2024_I2738509 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2024_I2738509);


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

    /// Book histograms and initialise projections before the run
    void init() {
      declare(FinalState(), "FS");
      book(_nK0K0, 1, 1, 2);
      for (const string& en : _nK0K0.binning().edges<0>()) {
        const double eval = stod(en);
        if (isCompatibleWithSqrtS(eval)) {
          _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)  _nK0K0->fill(_sqs);
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_nK0K0, crossSection()/ sumOfWeights() /picobarn);
    }

    /// @}


    /// @name Histograms
    /// @{
    BinnedHistoPtr<string> _nK0K0;
    string _sqs = "";
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BESIII_2024_I2738509);

}