Rivet analyses

title: PDG_R

PDG Compilation of $R$ measurements

Experiment: PDG (Various)

Inspire ID: 1688995

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D98 (2018) no.3, 030001

Beams: e+ e-

Beam energies: ANY

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

PDG compilation of measurements of the $R$ ratio in $e^+e^-$ collisions

Source code:PDG_R.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief Measurement of R class PDG_R : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(PDG_R);


/// @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<string>>(1, 1, 1));
  book(_c_muons, "/TMP/sigma_muons", refData<YODA::BinnedEstimate<string>>(1, 1, 1));
  for (const string& en : _c_hadrons.binning().edges<0>()) {
    const size_t idx1 = en.find("_");
    const string en2 = idx1 != std::string::npos ? en.substr(0, idx1) : en;
    const size_t idx2 = en.find("-");
    if (idx2 != string::npos) {
      const double emin = stod(en.substr(0, idx2));
      const double emax = stod(en.substr(idx2 + 1, string::npos));
      if (inRange(sqrtS() / GeV, emin, emax)) {
        _sqs.push_back(en);
        break;
      }
    }
    else {
      const double end = stod(en) * GeV;
      if (isCompatibleWithSqrtS(end)) {
        _sqs.push_back(en);
        break;
      }
    }
  }
  raiseBeamErrorIf(_sqs.empty());
}


/// 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]) {
    for (const string& en : _sqs) {
      _c_muons->fill(en);
    }
  }
  // everything else
  else {
    for (const string& en : _sqs) {
      _c_hadrons->fill(en);
    }
  }
}


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

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _c_hadrons, _c_muons;
vector<string> _sqs;
/// @}

};

RIVET_DECLARE_PLUGIN(PDG_R);

} ```