Rivet analyses

title: TASSO_1982_I176887

Measurement of $R$ between 12 and 36.7 GeV

Experiment: TASSO (PETRA)

Inspire ID: 176887

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B113 (1982) 499-508, 1982

Beams: e- e+

Beam energies: (7.0, 7.0); (11.0, 11.0); (12.5, 12.5); (17.0, 17.0); (17.5, 17.5)GeV

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

Measurement of $R$ in $e^+e^-$ collisions by TASSO for energies between 12 and 36.7 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:TASSO_1982_I176887.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief R measurement class TASSO_1982_I176887 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(TASSO_1982_I176887);


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

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

  // Book histograms
  for (size_t ix = 0; ix < 2; ++ix) {
    book(_c_hadrons[ix], "/TMP/sigma_hadrons_" + toString(2 * ix),
         refData<YODA::BinnedEstimate<string>>(1 + 2 * ix, 1, 1));
    book(_c_muons[ix], "/TMP/sigma_muons_" + toString(2 * ix),
         refData<YODA::BinnedEstimate<string>>(1 + 2 * ix, 1, 1));
    for (const string& en : _c_hadrons[ix].binning().edges<0>()) {
      const size_t idx = en.find("-");
      if (idx != string::npos) {
        const double emin = stod(en.substr(0, idx));
        const double emax = stod(en.substr(idx + 1, string::npos));
        if (inRange(sqrtS() / GeV, emin, emax)) {
          _sqs[ix] = en;
          break;
        }
      }
      else {
        const double eval = stod(en) * GeV;
        if (isCompatibleWithSqrtS(eval)) {
          _sqs[ix] = en;
          break;
        }
      }
    }
  }
  book(_c_hadronsI, "/TMP/sigma_hadrons_1", refData<YODA::BinnedEstimate<int>>(2, 1, 1));
  book(_c_muonsI, "/TMP/sigma_muons_1", refData<YODA::BinnedEstimate<int>>(2, 1, 1));
  for (int en : _c_hadronsI.binning().edges<0>()) {
    if (isCompatibleWithSqrtS(double(en))) {
      _isqs = en;
      break;
    }
  }
  raiseBeamErrorIf(_sqs[0].empty() && _sqs[1].empty() && _isqs < 0);
}


/// 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]) {
    // mu+mu- + photons
    if (!_sqs[0].empty()) _c_muons[0]->fill(_sqs[0]);
    if (!_sqs[1].empty()) _c_muons[1]->fill(_sqs[1]);
    if (_isqs > 0) _c_muonsI->fill(_isqs);
  }
  else {
    // everything else
    if (!_sqs[0].empty()) _c_hadrons[0]->fill(_sqs[0]);
    if (!_sqs[1].empty()) _c_hadrons[1]->fill(_sqs[1]);
    if (_isqs > 0) _c_hadronsI->fill(_isqs);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (size_t ix = 0; ix < 2; ++ix) {
    BinnedEstimatePtr<string> mult;
    book(mult, 1 + 2 * ix, 1, 1);
    divide(_c_hadrons[ix], _c_muons[ix], mult);
  }
  BinnedEstimatePtr<int> multI;
  book(multI, 2, 1, 1);
  divide(_c_hadronsI, _c_muonsI, multI);
}
/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _c_hadrons[2], _c_muons[2];
BinnedHistoPtr<int> _c_hadronsI, _c_muonsI;
string _sqs[2];
int _isqs = -1;
/// @}

};

RIVET_DECLARE_PLUGIN(TASSO_1982_I176887); } ```