Rivet analyses

title: BABAR_2020_I1769654

Cross section for $e^+e^-\to K_S^0K_L^0$ between 1.98 and 2.26 GeV

Experiment: BABAR (PEP-II)

Inspire ID: 1769654

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D101 (2020) no.1, 012011

Beams: * *

Beam energies: ANY

Run details: - e+e- to hadrons

Measurement of the cross section for $e^+e^-\to$ $K_S^0K_L^0$ via radiative return, including for energies between 1.98 and 2.26 GeV, N.B. the result is consistent with zero cross section

Source code:BABAR_2020_I1769654.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief e+e- > K0S K0L class BABAR_2020_I1769654 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2020_I1769654);


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

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

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

  // Book histograms
  book(_nKSKL, "TMP/nKSKL");
}


/// 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();
}


/// Normalise histograms etc., after the run
void finalize() {
  double sigma = _nKSKL->val() * crossSection() / sumOfWeights() / picobarn;
  double error = _nKSKL->err() * crossSection() / sumOfWeights() / picobarn;
  Estimate1DPtr mult;
  book(mult, 1, 1, 1);
  for (auto& b : mult->bins()) {
    if (inRange(sqrtS() / GeV, b.xMin(), b.xMax())) {
      b.set(sigma, error);
    }
  }
}

/// @}


/// @name Histograms
/// @{
CounterPtr _nKSKL;
/// @}

};

RIVET_DECLARE_PLUGIN(BABAR_2020_I1769654);

} ```