Rivet analyses

title: MARKII_1988_I261194

$\eta$ production at 29 GeV

Experiment: MARKII (PEP)

Inspire ID: 261194

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 61 (1988) 1057

Beams: e+ e-

Beam energies: (14.5, 14.5)GeV

Run details: - e+ e- to hadrons at 29 GeV

Rate and spectrum for $\eta$ meson production at 29 GeV measured by the MARKII collaboration.

Source code:MARKII_1988_I261194.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief eta production at 29 GeV class MARKII_1988_I261194 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(MARKII_1988_I261194);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(UnstableParticles(), "UFS");
  //Histograms
  book(_h_spect, 1, 1, 1);
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  if (_edges.empty()) _edges = _h_spect->xEdges();
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles(Cuts::abspid == 221)) {
    const double xp = 2. * p.E() / sqrtS();
    const double beta = p.p3().mod() / p.E();
    _h_spect->fill(map2string(xp), 1. / beta);
  }
}

string map2string(const double value) const {
  const size_t idx = _axis.index(value);
  if (idx && idx <= _edges.size()) return _edges[idx - 1];
  return "OTHER";
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_h_spect, sqr(sqrtS()) * crossSection() / microbarn / sumOfWeights());
  for (auto& b : _h_spect->bins()) {
    const size_t idx = b.index();
    b.scaleW(1. / _axis.width(idx));
  }
}

///@}


/// @name Histograms
///@{
BinnedHistoPtr<string> _h_spect;
vector<string> _edges;
YODA::Axis<double> _axis{0.2, 0.3, 0.35, 0.4, 0.45, 0.525, 0.625, 0.725};
///@}

};

RIVET_DECLARE_PLUGIN(MARKII_1988_I261194);

} ```