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KEDR_2019_I1673357

Measurement of $R$ between 1.84 and 3.72 GeV
Experiment: KEDR (VEPP-4M)
Inspire ID: 1673357
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. B788 (2019) 42-51
Beams: e+ e-
Beam energies: ANY
Run details:
  • e+e- to hadrons and muon so the ratio can be computed

Measurement of $R$ for centre-of-mass energies between 1.84 and 3.72 GeV by the KEDR experiment.

Source code: KEDR_2019_I1673357.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/FinalState.hh"
  4
  5namespace Rivet {
  6
  7
  8  /// @brief Measurement of R
  9  class KEDR_2019_I1673357 : public Analysis {
 10  public:
 11
 12    /// Constructor
 13    RIVET_DEFAULT_ANALYSIS_CTOR(KEDR_2019_I1673357);
 14
 15
 16    /// @name Analysis methods
 17    //@{
 18
 19    /// Book histograms and initialise projections before the run
 20    void init() {
 21      // Initialise and register projections
 22      declare(FinalState(), "FS");
 23
 24      // Book histograms
 25      book(_c_hadrons, "/TMP/sigma_hadrons");
 26      book(_c_muons, "/TMP/sigma_muons");
 27    }
 28
 29
 30    /// Perform the per-event analysis
 31    void analyze(const Event& event) {
 32      const FinalState& fs = apply<FinalState>(event, "FS");
 33
 34      map<long,int> nCount;
 35      int ntotal(0);
 36      for (const Particle& p : fs.particles()) {
 37	nCount[p.pid()] += 1;
 38	++ntotal;
 39      }
 40      // mu+mu- + photons
 41      if(nCount[-13]==1 and nCount[13]==1 &&
 42	 ntotal==2+nCount[22])
 43	_c_muons->fill();
 44      // everything else
 45      else
 46	_c_hadrons->fill();
 47    }
 48
 49
 50    /// Normalise histograms etc., after the run
 51    void finalize() {
 52      Scatter1D R = *_c_hadrons/ *_c_muons;
 53      double              rval = R.point(0).x();
 54      pair<double,double> rerr = R.point(0).xErrs();
 55      double fact = crossSection()/ sumOfWeights() /picobarn;
 56      double sig_h = _c_hadrons->val()*fact;
 57      double err_h = _c_hadrons->err()*fact;
 58      double sig_m = _c_muons  ->val()*fact;
 59      double err_m = _c_muons  ->err()*fact;
 60      Scatter2D temphisto(refData(1, 1, 1));
 61      Scatter2DPtr hadrons;
 62      book(hadrons, "sigma_hadrons");
 63      Scatter2DPtr muons;
 64      book(muons, "sigma_muons"  );
 65      Scatter2DPtr mult1,mult2;
 66      book(mult1, 1, 1, 1);
 67      book(mult2, 1, 1, 2);
 68      for (size_t b = 0; b < temphisto.numPoints(); b++) {
 69        const double x  = temphisto.point(b).x();
 70        pair<double,double> ex = temphisto.point(b).xErrs();
 71        pair<double,double> ex2 = ex;
 72        if(ex2.first ==0.) ex2. first=0.0001;
 73        if(ex2.second==0.) ex2.second=0.0001;
 74        if (inRange(sqrtS()/MeV, x-ex2.first, x+ex2.second)) {
 75          mult1   ->addPoint(x, rval, ex, rerr);
 76          mult2   ->addPoint(x, rval, ex, rerr);
 77          hadrons ->addPoint(x, sig_h, ex, make_pair(err_h,err_h));
 78          muons   ->addPoint(x, sig_m, ex, make_pair(err_m,err_m));
 79        }
 80        else {
 81          mult1   ->addPoint(x, 0., ex, make_pair(0.,.0));
 82          mult2   ->addPoint(x, 0., ex, make_pair(0.,.0));
 83          hadrons ->addPoint(x, 0., ex, make_pair(0.,.0));
 84          muons   ->addPoint(x, 0., ex, make_pair(0.,.0));
 85        }
 86      }
 87    }
 88
 89    //@}
 90
 91
 92    /// @name Histograms
 93    //@{
 94    CounterPtr _c_hadrons, _c_muons;
 95    //@}
 96
 97
 98  };
 99
100
101  RIVET_DECLARE_PLUGIN(KEDR_2019_I1673357);
102
103}