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GAMMAGAMMA_1979_I141722

Measurement of $R$ and the hadron multiplicity between 1.42 and 3.09 GeV
Experiment: GAMMAGAMMA (ADONE)
Inspire ID: 141722
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett. B86 (1979) 234-238, 1979
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 Gamma-Gamma-2 for energies between 1.42 and 3.09 GeV. The average charged and neutral particle multiplicity is also measured. The individual hadronic and muonic cross sections are also outputted to the yoda file so that ratio $R$ can be recalcuated if runs are combined.

Source code: GAMMAGAMMA_1979_I141722.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"

namespace Rivet {


  /// @brief Add a short analysis description here
  class GAMMAGAMMA_1979_I141722 : public Analysis {
  public:

    /// Constructor
    DEFAULT_RIVET_ANALYSIS_CTOR(GAMMAGAMMA_1979_I141722);


    /// @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");
      book(_c_muons, "/TMP/sigma_muons");
      book(_c_charged, "/TMP/Ncharged");
      book(_c_neutral, "/TMP/Nneutral");
      book(_nHadrons, "/TMP/NHadrons");
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const FinalState& fs = apply<FinalState>(event, "FS");

      map<long,int> nCount;
      int ntotal(0),ncharged(0),nneutral(0);
      for (const Particle& p : fs.particles()) {
	nCount[p.pid()] += 1;
	++ntotal;
	if(PID::isCharged(p.pid()))
	  ncharged += 1;
	else
	  nneutral += 1;
      }
      // mu+mu- + photons
      if(nCount[-13]==1 and nCount[13]==1 &&
	 ntotal==2+nCount[22])
	_c_muons->fill();
      // everything else
      else {
	if(ntotal==2) vetoEvent;
	_c_hadrons->fill();
	_c_charged->fill(ncharged);
	_c_neutral->fill(nneutral);
	_nHadrons->fill();
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      Scatter1D R = *_c_hadrons/ *_c_muons;
      double              rval = R.point(0).x();
      pair<double,double> rerr = R.point(0).xErrs();
      double fact = crossSection()/ sumOfWeights() /picobarn;
      double sig_h = _c_hadrons->val()*fact;
      double err_h = _c_hadrons->err()*fact;
      double sig_m = _c_muons  ->val()*fact;
      double err_m = _c_muons  ->err()*fact;
      Scatter2D temphisto(refData(1, 1, 1));
      Scatter2DPtr hadrons;
      book(hadrons, "sigma_hadrons");
      Scatter2DPtr muons;
      book(muons, "sigma_muons"  );
      Scatter2DPtr mult;
      book(mult, 1, 1, 1);
      for (size_t b = 0; b < temphisto.numPoints(); b++) {
	const double x  = temphisto.point(b).x();
	pair<double,double> ex = temphisto.point(b).xErrs();
	pair<double,double> ex2 = ex;
	if(ex2.first ==0.) ex2. first=0.0001;
	if(ex2.second==0.) ex2.second=0.0001;
	if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
	  mult   ->addPoint(x, rval, ex, rerr);
	  hadrons->addPoint(x, sig_h, ex, make_pair(err_h,err_h));
	  muons  ->addPoint(x, sig_m, ex, make_pair(err_m,err_m));
	}
	else {
	  mult   ->addPoint(x, 0., ex, make_pair(0.,.0));
	  hadrons->addPoint(x, 0., ex, make_pair(0.,.0));
	  muons  ->addPoint(x, 0., ex, make_pair(0.,.0));
	}
      }
      scale(_c_charged, 1./_nHadrons->sumW());
      scale(_c_neutral, 1./_nHadrons->sumW());
      for(unsigned int iy=1; iy<3;++iy) {
	double aver(0.),error(0.);
	if(iy==1) {
	  aver  = _c_charged->val();
	  error = _c_charged->err();
	}
	else {
	  aver  = _c_neutral->val();
	  error = _c_neutral->err();
	}
	Scatter2D temphisto(refData(2, 1, iy));
	Scatter2DPtr mult;
	book(mult, 2, 1, iy);
	for (size_t b = 0; b < temphisto.numPoints(); b++) {
	  const double x  = temphisto.point(b).x();
	  pair<double,double> ex = temphisto.point(b).xErrs();
	  pair<double,double> ex2 = ex;
	  if(ex2.first ==0.) ex2. first=0.0001;
	  if(ex2.second==0.) ex2.second=0.0001;
	  if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
	    mult   ->addPoint(x, aver, ex, make_pair(error,error));
	  }
	  else {
	    mult   ->addPoint(x, 0., ex, make_pair(0.,.0));
	  }
	}
      }
    }

    //@}


    /// @name Histograms
    //@{
    CounterPtr _c_hadrons, _c_muons,_c_neutral,_c_charged;
    CounterPtr _nHadrons;
    //@}


  };


  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(GAMMAGAMMA_1979_I141722);


}