Rivet analyses

title: BABAR_2013_I1238807

Cross section for $e^+e^-\to K^+K^-$ between threshold and 5 GeV

Experiment: BABAR (PEP-II)

Inspire ID: 1238807

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D88 (2013) no.3, 032013

Beams: e+ e-

Beam energies: ANY

Run details: - e+ e- to hadrons

Measurement of the cross section for $e^+e^-\to K^+K^-$ at energies between threshold and 5 GeV using radiative return

Source code:BABAR_2013_I1238807.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief Add a short analysis description here class BABAR_2013_I1238807 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2013_I1238807);


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

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

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

  // Book histograms
  book(_nkaon, "TMP/kaon");
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  const FinalState& fs = apply<FinalState>(event, "FS");
  if (fs.particles().size() != 2) vetoEvent;
  for (const Particle& p : fs.particles()) {
    if (abs(p.pid()) != PID::KPLUS) vetoEvent;
  }
  _nkaon->fill();
}


/// Normalise histograms etc., after the run
void finalize() {
  double sigma = _nkaon->val();
  double error = _nkaon->err();
  sigma *= crossSection() / sumOfWeights() / nanobarn;
  error *= crossSection() / sumOfWeights() / nanobarn;
  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 _nkaon;
/// @}

};

RIVET_DECLARE_PLUGIN(BABAR_2013_I1238807);

} ```