Rivet analyses

title: VENUS_1987_I251274

Measurement of $R$ for energies between 50 and 52 GeV

Experiment: VENUS (Tristan)

Inspire ID: 251274

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B198 (1987) 570, 1987

Beams: e- e+

Beam energies: (25.0, 25.0); (26.0, 26.0)GeV

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

Measurement of $R$ in $e^+e^-$ collisions by VENUS for energies between 50 and 52 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:VENUS_1987_I251274.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief R measurement class VENUS_1987_I251274 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(VENUS_1987_I251274);


/// @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, "/TMP/sigma_hadrons", refData<YODA::BinnedEstimate<int>>(1, 1, 1));
  book(_c_muons, "/TMP/sigma_muons", refData<YODA::BinnedEstimate<int>>(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(round(sqrtS() / GeV));
  // everything else
  else
    _c_hadrons->fill(round(sqrtS() / GeV));
}


/// Normalise histograms etc., after the run
void finalize() {
  BinnedEstimatePtr<int> mult;
  book(mult, 1, 1, 1);
  divide(_c_hadrons, _c_muons, mult);
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<int> _c_hadrons, _c_muons;
/// @}

};

RIVET_DECLARE_PLUGIN(VENUS_1987_I251274);

} ```