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CRYSTAL_BALL_1986_I238081

Measurement of $R$ and $D^*$ production for energies between 3.67 and 4.5 GeV.
Experiment: CRYSTAL_BALL (Spear)
Inspire ID: 238081
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • https://doi.org/10.17182/hepdata.18759
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 the Crystal Ball experiment for energies between 3.67 and 4.5 GeV. The cross section for $D^*$ production 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: CRYSTAL_BALL_1986_I238081.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief Add a short analysis description here
  class CRYSTAL_BALL_1986_I238081 : public Analysis {
  public:

    /// Constructor
    DEFAULT_RIVET_ANALYSIS_CTOR(CRYSTAL_BALL_1986_I238081);


    /// @name Analysis methods
    //@{

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(FinalState(), "FS");
      declare(UnstableParticles(), "UFS");

      // Book histograms
      book(_c_hadrons, "/TMP/sigma_hadrons");
      book(_c_muons, "/TMP/sigma_muons");
      book(_c_D_star, "/TMP/sigma_D_star");
    }


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

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

      const FinalState& ufs = apply<UnstableParticles>(event, "UFS");
      bool found = false;
      for (const Particle & p : ufs.particles()) {
	if(abs(p.pid())!=413 && abs(p.pid())!=423) continue;
	bool fs = true;
	for (const Particle & child : p.children()) {
	  if(child.pid()==p.pid()) {
	    fs = false;
	    break;
	  }
	}
	if(fs) {
	  found = true;
	  break;
	}
      }
      if(found) 
	_c_D_star->fill();
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // R
      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));
	}
      }
      // D*
      fact = crossSection()/ sumOfWeights() /nanobarn;
      double sigma = _c_D_star->val()*fact;
      double error = _c_D_star->err()*fact;
      Scatter2D temphisto2(refData(2, 1, 1));
      Scatter2DPtr mult2;
      book(mult2, 2, 1, 1);
      for (size_t b = 0; b < temphisto2.numPoints(); b++) {
      	const double x  = temphisto2.point(b).x();
      	pair<double,double> ex = temphisto2.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)) {
      	  mult2   ->addPoint(x, sigma, ex, make_pair(error,error));
      	}
      	else {
      	  mult2   ->addPoint(x, 0., ex, make_pair(0.,.0));
      	}
      }
    }

    //@}


    /// @name Histograms
    //@{
    CounterPtr _c_hadrons, _c_muons,_c_D_star;
    //@}


  };


  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(CRYSTAL_BALL_1986_I238081);


}