Rivet analyses

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++ -*-
#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);
}