Rivet analyses

title: SND_2016_I1484677

Cross section for $e^+e^-\to K^+K^-$ between 1.05 and 2 GeV

Experiment: SND (VEPP-2M)

Inspire ID: 1484677

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D94 (2016) no.11, 112006

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 1.05 and 2 GeV

Source code:SND_2016_I1484677.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief e+ e- > K+K- class SND_2016_I1484677 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(SND_2016_I1484677);


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

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

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

  // Book histograms
  for (size_t ix = 0; ix < 2; ++ix) {
    book(_nkaon[ix], 1 + ix, 1, 1);
    for (const string& en : _nkaon[ix].binning().edges<0>()) {
      const double eval = stod(en) * GeV;
      if (isCompatibleWithSqrtS(eval)) {
        _sqs[ix] = en;
        break;
      }
    }
  }
  raiseBeamErrorIf(_sqs[0].empty() && _sqs[1].empty());
}


/// 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 (p.abspid() != PID::KPLUS) vetoEvent;
  }
  for (size_t ix = 0; ix < 2; ++ix) _nkaon[ix]->fill(_sqs[ix]);
}


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

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _nkaon[2];
string _sqs[2];
/// @}

};

RIVET_DECLARE_PLUGIN(SND_2016_I1484677); } ```