Rivet analyses

title: MARKJ_1979_I141976

Measurement of $R$ at 31.57 GeV

Experiment: MARKJ (PETRA)

Inspire ID: 141976

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B85 (1979) 463-466, 1979

Beams: e- e+

Beam energies: ANY

Run details: - e+ e- to hadrons and e+ e- to mu+ mu- (for normalization)

Measurement of $R$ in $e^+e^-$ collisions by MARKJ for 31.57 GeV. The individual hadronic and muonic cross sections are also outputted to the yoda file so that ratio $R$ can be recalculated if runs are combined.

Source code:MARKJ_1979_I141976.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief Add a short analysis description here class MARKJ_1979_I141976 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(MARKJ_1979_I141976);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");

  // Book histograms
  book(_c_hadrons, "sigma_hadrons", refData<YODA::BinnedEstimate<string>>(1, 1, 1));
  book(_c_muons, "sigma_muons", refData<YODA::BinnedEstimate<string>>(1, 1, 1));
}


/// 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;
  }
  // mu+mu- + photons
  if (nCount[-13] == 1 and nCount[13] == 1 && ntotal == 2 + nCount[22]) {
    _c_muons->fill(Ecm);
  }
  // everything else
  else {
    _c_hadrons->fill(Ecm);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  const double fact = crossSection() / sumOfWeights() / picobarn;
  scale({_c_hadrons, _c_muons}, fact);
  BinnedEstimatePtr<string> mult;
  book(mult, 1, 1, 1);
  divide(_c_hadrons, _c_muons, mult);
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _c_hadrons, _c_muons;
const string Ecm = "31.57";
/// @}

};

RIVET_DECLARE_PLUGIN(MARKJ_1979_I141976);

} ```