rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

BESII_2009_I814778

Measurement of $R$ for energies between 2.6 and 3.65 GeV
Experiment: BESII (BEPC)
Inspire ID: 814778
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. B677 (2009) 239-245, 2009
Beams: e- e+
Beam energies: ANY
Run details:
  • e+ e- to hadrons and e+ e- to mu+ mu- (for normalization)

Measurement of $R$ in $e^+e^-$ collisions by BESII for energies between 2.6 and 3.65 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: BESII_2009_I814778.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/FinalState.hh"
  4
  5namespace Rivet {
  6
  7
  8  /// @brief Add a short analysis description here
  9  class BESII_2009_I814778 : public Analysis {
 10  public:
 11
 12    /// Constructor
 13    RIVET_DEFAULT_ANALYSIS_CTOR(BESII_2009_I814778);
 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      // Book histograms
 24      book(_c_hadrons, "/TMP/sigma_hadrons");
 25      book(_c_muons, "/TMP/sigma_muons");
 26    }
 27
 28
 29    /// Perform the per-event analysis
 30    void analyze(const Event& event) {
 31      const FinalState& fs = apply<FinalState>(event, "FS");
 32
 33      map<long,int> nCount;
 34      int ntotal(0);
 35      for (const Particle& p : fs.particles()) {
 36	nCount[p.pid()] += 1;
 37	++ntotal;
 38      }
 39      // mu+mu- + photons
 40      if(nCount[-13]==1 and nCount[13]==1 &&
 41	 ntotal==2+nCount[22])
 42	_c_muons->fill();
 43      // everything else
 44      else
 45	_c_hadrons->fill();
 46    }
 47
 48
 49    /// Normalise histograms etc., after the run
 50    void finalize() {
 51      Scatter1D R = *_c_hadrons/ *_c_muons;
 52      double              rval = R.point(0).x();
 53      pair<double,double> rerr = R.point(0).xErrs();
 54      double fact = crossSection()/ sumOfWeights() /nanobarn;
 55      double sig_h = _c_hadrons->val()*fact;
 56      double err_h = _c_hadrons->err()*fact;
 57      double sig_m = _c_muons  ->val()*fact;
 58      double err_m = _c_muons  ->err()*fact;
 59      Scatter2D temphisto(refData(1, 1, 1));
 60      Scatter2DPtr hadrons;
 61      book(hadrons, "sigma_hadrons");
 62      Scatter2DPtr muons;
 63      book(muons, "sigma_muons"  );
 64      Scatter2DPtr     mult;
 65      book(mult, 1, 1, 1);
 66      for (size_t b = 0; b < temphisto.numPoints(); b++) {
 67	const double x  = temphisto.point(b).x();
 68	pair<double,double> ex = temphisto.point(b).xErrs();
 69	pair<double,double> ex2 = ex;
 70	if(ex2.first ==0.) ex2. first=0.0001;
 71	if(ex2.second==0.) ex2.second=0.0001;
 72	if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
 73	  mult   ->addPoint(x, rval, ex, rerr);
 74	  hadrons->addPoint(x, sig_h, ex, make_pair(err_h,err_h));
 75	  muons  ->addPoint(x, sig_m, ex, make_pair(err_m,err_m));
 76	}
 77	else {
 78	  mult   ->addPoint(x, 0., ex, make_pair(0.,.0));
 79	  hadrons->addPoint(x, 0., ex, make_pair(0.,.0));
 80	  muons  ->addPoint(x, 0., ex, make_pair(0.,.0));
 81	}
 82      }
 83    }
 84
 85    //@}
 86
 87
 88    /// @name Histograms
 89    //@{
 90    CounterPtr _c_hadrons, _c_muons;
 91    //@}
 92
 93
 94  };
 95
 96
 97  // The hook for the plugin system
 98  RIVET_DECLARE_PLUGIN(BESII_2009_I814778);
 99
100
101}