Rivet analyses

Measurement of R for energies between 12 and 39 GeV

Experiment: TASSO (PETRA)

Inspire ID: 143690

Status: VALIDATED

Authors: - Peter Richardson

References: - Z.Phys. C4 (1980) 87, 1980

Beams: e- e+

Beam energies: (6.0, 6.0); (6.5, 6.5); (8.5, 8.5); (11.0, 11.0)GeV

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

Measurement of R in e+e− collisions for energies between 12 and 39 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_1980_I143690.cc

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"

namespace Rivet {


  /// @brief  R measurement
  class TASSO_1980_I143690 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(TASSO_1980_I143690);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(FinalState(), "FS");
      // counters for R
      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 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 = en; break;
          }
        }
        else {
          const double eval = stod(en)*GeV;
          if (isCompatibleWithSqrtS(eval)) {
            _sqs = 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;
      }
      if (nCount[-13]==1 && nCount[13]==1 && ntotal==2+nCount[22]) {
        // mu+mu- + photons
        _c_muons->fill(_sqs);
      }
      else {
        _c_hadrons->fill(_sqs); // everything else
      }
    }


    /// 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;
    string _sqs = "";
    /// @}


  };


  RIVET_DECLARE_PLUGIN(TASSO_1980_I143690);
}