Rivet analyses

title: CELLO_1989_I266414

$\gamma\gamma\to K^0_SK^\pm\pi^\mp$ for centre-of-mass energies between 1.4 and 4.2 GeV

Experiment: CELLO (PETRA)

Inspire ID: 266414

Status: VALIDATED

Authors: - Peter Richardson

References: - Z.Phys.C 42 (1989) 367

Beams: 22 22

Beam energies: ANY

Run details: - gamma gamma to hadrons, K0S mesons must be set stable

Measurement of the differential cross section for $\gamma\gamma\to K^0_SK^\pm\pi^\mp$ for $1.4 \text{GeV} < W < 4.2 \text{GeV}$. The cross section is measured as a function of the centre-of-mass energy of the photonic collision.

Source code:CELLO_1989_I266414.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief gamma gamma -> KKpi class CELLO_1989_I266414 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CELLO_1989_I266414);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");
  // book histos
  if (inRange(sqrtS() / GeV, 1.4, 4.2)) {
    book(_nKKPi, "TMP/nKKPi");
  }
  else {
    throw Error("Invalid CMS energy for CELLO_1989_I266414");
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  const FinalState& fs = apply<FinalState>(event, "FS");
  // find the final-state particles
  map<long, int> nCount;
  int ntotal(0);
  for (const Particle& p : fs.particles()) {
    nCount[p.pid()] += 1;
    ++ntotal;
  }
  if (ntotal != 3) vetoEvent;
  if (nCount[PID::K0S] == 1
      && ((nCount[PID::PIPLUS] == 1 && nCount[PID::KMINUS] == 1)
          || (nCount[PID::PIMINUS] == 1 && nCount[PID::KPLUS] == 1))) {
    _nKKPi->fill();
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_nKKPi, crossSection() / nanobarn / sumOfWeights());
  Estimate1DPtr mult;
  book(mult, 1, 1, 1);
  for (auto& b : mult->bins()) {
    if (inRange(sqrtS() / GeV, b.xMin(), b.xMax())) {
      b.set(_nKKPi->val(), _nKKPi->err());
    }
  }
}

/// @}


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

};

RIVET_DECLARE_PLUGIN(CELLO_1989_I266414);

} ```