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PLUTO_1977_I110272

Measurement of $R$ for energies between 3.1 and 4.8 GeV
Experiment: PLUTO (DORIS)
Inspire ID: 110272
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. B66 (1977) 395-400, 1977
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 PLUTO for energies between 3.1 and 4.8 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: PLUTO_1977_I110272.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/FinalState.hh"
  4
  5namespace Rivet {
  6
  7
  8  /// @brief R for energies between 3.1 and 4.8 GeV
  9  class PLUTO_1977_I110272 : public Analysis {
 10  public:
 11
 12    /// Constructor
 13    RIVET_DEFAULT_ANALYSIS_CTOR(PLUTO_1977_I110272);
 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
 31    /// Perform the per-event analysis
 32    void analyze(const Event& event) {
 33      const FinalState& fs = apply<FinalState>(event, "FS");
 34
 35      map<long,int> nCount;
 36      int ntotal(0);
 37      for (const Particle& p : fs.particles()) {
 38	nCount[p.pid()] += 1;
 39	++ntotal;
 40      }
 41      // mu+mu- + photons
 42      if(nCount[-13]==1 and nCount[13]==1 &&
 43	 ntotal==2+nCount[22])
 44	_c_muons->fill();
 45      // everything else
 46      else
 47	_c_hadrons->fill();
 48    }
 49
 50
 51    /// Normalise histograms etc., after the run
 52    void finalize() {
 53      Scatter1D R = *_c_hadrons/ *_c_muons;
 54      double              rval = R.point(0).x();
 55      pair<double,double> rerr = R.point(0).xErrs();
 56      double fact = crossSection()/ sumOfWeights() /picobarn;
 57      double sig_h = _c_hadrons->val()*fact;
 58      double err_h = _c_hadrons->err()*fact;
 59      double sig_m = _c_muons  ->val()*fact;
 60      double err_m = _c_muons  ->err()*fact;
 61      Scatter2D temphisto(refData(2, 1, 1));
 62      Scatter2DPtr hadrons;
 63      book(hadrons, "sigma_hadrons");
 64      Scatter2DPtr muons;
 65      book(muons,   "sigma_muons"  );
 66      Scatter2DPtr mult;
 67      book(mult, 2, 1, 1);
 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()/GeV, x-ex2.first, x+ex2.second)) {
 75	  mult   ->addPoint(x, rval, ex, rerr);
 76	  hadrons->addPoint(x, sig_h, ex, make_pair(err_h,err_h));
 77	  muons  ->addPoint(x, sig_m, ex, make_pair(err_m,err_m));
 78	}
 79	else {
 80	  mult   ->addPoint(x, 0., ex, make_pair(0.,.0));
 81	  hadrons->addPoint(x, 0., ex, make_pair(0.,.0));
 82	  muons  ->addPoint(x, 0., ex, make_pair(0.,.0));
 83	}
 84      }
 85    }
 86
 87    //@}
 88
 89
 90    /// @name Histograms
 91    //@{
 92    CounterPtr _c_hadrons, _c_muons;
 93    //@}
 94
 95
 96  };
 97
 98
 99  // The hook for the plugin system
100  RIVET_DECLARE_PLUGIN(PLUTO_1977_I110272);
101
102
103}