Rivet analyses

title: BESIII_2024_I2738509

Cross section for $e^+e^-\to K^0_SK^0_L$ 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 $e^+e^-\to K^0_SK^0_L$ for $\sqrt{s}$ between 3.51 GeV and 4.95 GeV measured by BES

Source code:BESIII_2024_I2738509.cc

```c++ // -- 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);

} ```