Rivet analyses

Measurement of R for energies between 50 and 61.4 GeV

Experiment: VENUS (Tristan)

Inspire ID: 283774

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B234 (1990) 382-388, 1990

Beams: e- e+

Beam energies: (27.0, 27.0); (27.5, 27.5); (28.0, 28.0); (28.2, 28.2); (28.5, 28.5); (29.2, 29.2); (29.5, 29.5); (29.5, 29.5); (30.0, 30.0); (30.4, 30.4); (30.7, 30.7)GeV

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

Measurement of R in e+e− collisions by VENUS for energies between 50 and 61.4 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:VENUS_1990_I283774.cc

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

namespace Rivet {


  /// @brief R measurement
  class VENUS_1990_I283774 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(VENUS_1990_I283774);


    /// @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 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 and 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(VENUS_1990_I283774);
}