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ARGUS_1992_I319102

Measurement of $R$ at 9.36 GeV and charged particle multiplcities in continuum and at the $\Upsilon(4S)$
Experiment: ARGUS (DORIS)
Inspire ID: 319102
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Z.Phys. C54 (1992) 13-20, 1992
Beams: e- e+
Beam energies: ANY
Run details:
  • e+ e- to hadrons and e+ e- to mu+ mu- (for normalization)

Measurement of $R$ at 9.36 GeV and charged particle multiplcities in continuum and at the $\Upsilon(4S)$. 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: ARGUS_1992_I319102.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief charged multiplicity at 4s and nearby continuum
  class ARGUS_1992_I319102 : public Analysis {
  public:

    /// Constructor
    DEFAULT_RIVET_ANALYSIS_CTOR(ARGUS_1992_I319102);


    /// @name Analysis methods
    //@{

    /// Book histograms and initialise projections before the run
    void init() {

      // Initialise and register projections
      declare(UnstableParticles(), "UFS");
      declare(FinalState(), "FS");

      // Book histograms
      if(fuzzyEquals(sqrtS()/GeV, 10.47 , 1E-3))
	book(_h_N, 2, 1, 1);
      book(_h_N_Upsilon, 3, 1, 1);
      // counters for R
      book(_c_hadrons, "/TMP/sigma_hadrons");
      book(_c_muons, "/TMP/sigma_muons");
    }

    /// Recursively walk the decay tree to find decay products of @a p
    void findDecayProducts(Particle mother, unsigned int & nCharged) {
      for(const Particle & p: mother.children()) {
	if(!p.children().empty())
	  findDecayProducts(p, nCharged);
	else if(PID::isCharged(p.pid()))
	  ++nCharged;
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const FinalState& fs = apply<FinalState>(event, "FS");
      // Find the Upsilons among the unstables
      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
      Particles upsilons = ufs.particles(Cuts::pid==300553);
      // Continuum
      if (upsilons.empty()) {
	map<long,int> nCount;
	int ntotal(0);
	unsigned int nCharged(0);
	for (const Particle& p : fs.particles()) {
	  nCount[p.pid()] += 1;
	  ++ntotal;
	  if(PID::isCharged(p.pid())) ++nCharged;
	}
	// mu+mu- + photons
	if(nCount[-13]==1 and nCount[13]==1 &&
	   ntotal==2+nCount[22])
	  _c_muons->fill();
	// everything else
	else {
	  _c_hadrons->fill();
	  if(_h_N)
	    _h_N->fill(nCharged);
	}
      }
      // upsilon 4s
      else {
        for (const Particle& ups : upsilons) {
	  unsigned int nCharged(0);
	  findDecayProducts(ups,nCharged);
	  _h_N_Upsilon->fill(nCharged);
	}
      }
    }


    /// 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));
	}
      }
      if(_h_N) {
	normalize(_h_N,200.);
      }
	normalize(_h_N_Upsilon,200.);
    }

    //@}


    /// @name Histograms
    //@{
    Histo1DPtr _h_N,_h_N_Upsilon;
    CounterPtr _c_hadrons, _c_muons;
    //@}


  };


  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(ARGUS_1992_I319102);


}