Rivet analyses

title: NMD_1974_I745

Measurement of $R$ and the hadronic cross section for 4 GeV

Experiment: NMD (CEA)

Inspire ID: 745

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 32 (1974) 432-435, 1974

Beams: e- e+

Beam energies: ANY

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

Measurement of $R$ and the hadronic cross seection in $e^+e^-$ collisions by the Non-Magnetic Detector at 4 GeV. The muonic cross section is also outputted to the yoda file so that ratio $R$ can be recalcuated if runs are combined.

Source code:NMD_1974_I745.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief Add a short analysis description here class NMD_1974_I745 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(NMD_1974_I745);


/// @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, 1, 1, 1);
  book(_c_muons, "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;
  }
  if (nCount[-13] == 1 and nCount[13] == 1 && ntotal == 2 + nCount[22]) {
    _c_muons->fill(4); // mu+mu- + photons
  }
  else {
    _c_hadrons->fill(4); // everything else
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  const double fact = crossSection() / sumOfWeights() / nanobarn;
  scale({_c_hadrons, _c_muons}, fact);
  BinnedEstimatePtr<int> mult;
  book(mult, 1, 1, 2);
  divide(_c_hadrons, _c_muons, mult);
}

/// @}


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

};

RIVET_DECLARE_PLUGIN(NMD_1974_I745);

} ```