Rivet Analyses Reference

DELPHI_2000_S4328825

Hadronization properties of $b$ quarks compared to light quarks in $e^+ e^-\to q \bar{q}$ from 183 GeV to 200 GeV
Experiment: OPAL (LEP 2)
Inspire ID: 524693
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Lett.B479:118-128,2000
  • hep-ex/0103022
  • DELPHI 2002-052 CONF 586
Beams: e+ e-
Beam energies: (91.5, 91.5); (94.5, 94.5); (96.0, 96.0); (98.0, 98.0); (100.0, 100.0); (103.0, 103.0) GeV
Run details:
  • Hadronic Z decay events generated on the Z pole ($\sqrt{s} = 91.2$ GeV)

Measurements of the mean charged multiplicities separately for $b\bar b$, $c\bar{c}$ and light quark ($uds$) initiated events in $e^+e^-$ interactions at energies above the $Z^0$ mass. In addition to the energy points in the original paper one additional point at 206;GeV is included from a later preliminary result.

Source code: DELPHI_2000_S4328825.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/Beam.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/Sphericity.hh"
#include "Rivet/Projections/Thrust.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/ParisiTensor.hh"
#include "Rivet/Projections/Hemispheres.hh"
#include <cmath>

#define I_KNOW_THE_INITIAL_QUARKS_PROJECTION_IS_DODGY_BUT_NEED_TO_USE_IT
#include "Rivet/Projections/InitialQuarks.hh"

namespace Rivet {


  /// @brief DELPHI multiplicities at various energies
  ///
  /// @author Peter Richardson
  class DELPHI_2000_S4328825 : public Analysis {
  public:

    RIVET_DEFAULT_ANALYSIS_CTOR(DELPHI_2000_S4328825);


    /// @name Analysis methods
    /// @{

    void init() {
      // Projections
      declare(Beam(), "Beams");
      declare(ChargedFinalState(), "CFS");
      declare(InitialQuarks(), "IQF");
      book(_cLight,  "/TMP/CLIGHT" );
      book(_cCharm,  "/TMP/CCHARM" );
      book(_cBottom, "/TMP/CBOTTOM");

      book(_wLight, "_weight_light");
      book(_wCharm, "_weight_charm");
      book(_wBottom,"_weight_bottom");

      _mult.resize(4);
      book(_mult[0], 1, 1, 1);
      book(_mult[1], 1, 1, 2);
      book(_mult[2], 1, 1, 3);
      book(_mult[3], 1, 1, 4);  // bottom minus light

    }


    void analyze(const Event& event) {
      // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
      const FinalState& cfs = apply<FinalState>(event, "CFS");
      if (cfs.size() < 2) vetoEvent;


      int flavour = 0;
      const InitialQuarks& iqf = apply<InitialQuarks>(event, "IQF");

      // If we only have two quarks (qqbar), just take the flavour.
      // If we have more than two quarks, look for the highest energetic q-qbar pair.
      if (iqf.particles().size() == 2) {
        flavour = iqf.particles().front().abspid();
      }
      else {
        map<int, double> quarkmap;
        for (const Particle& p : iqf.particles()) {
          if (quarkmap[p.pid()] < p.E()) {
            quarkmap[p.pid()] = p.E();
          }
        }
        double maxenergy = 0.;
        for (int i = 1; i <= 5; ++i) {
          if (quarkmap[i]+quarkmap[-i] > maxenergy) {
            flavour = i;
          }
        }
      }
      const size_t numParticles = cfs.particles().size();
      switch (flavour) {
      case 1: case 2: case 3:
        _wLight->fill();
        _cLight->fill(numParticles);
        break;
      case 4:
        _wCharm->fill();
        _cCharm->fill(numParticles);
        break;
      case 5:
        _wBottom->fill();
        _cBottom->fill(numParticles);
        break;
      }
    }


    void finalize() {

      // calculate the averages and diffs
      if(_wLight->val()  != 0.)  scale(_cLight,  1./(*_wLight));
      if(_wCharm->val()  != 0.)  scale(_cCharm,  1./(*_wCharm));
      if(_wBottom->val() != 0.)  scale(_cBottom, 1./(*_wBottom));
      Counter _cDiff = *_cBottom - *_cLight;

      // fill the histograms
      for (unsigned int ix=1; ix < 5; ++ix) {
        double val(0.), err(0.0);
        if(ix==1) {
          val = _cBottom->val();
          err = _cBottom->err();
        }
        else if(ix==2) {
          val = _cCharm->val();
          err = _cCharm->err();
        }
        else if(ix==3) {
          val = _cLight->val();
          err = _cLight->err();
        }
        else if(ix==4) {
          val = _cDiff.val();
          err = _cDiff.err();
        }
        Scatter2D temphisto(refData(1, 1, ix));
        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[ix-1]->addPoint(x, val, ex, make_pair(err,err));
          }
          else {
            _mult[ix-1]->addPoint(x, 0., ex, make_pair(0.,.0));
          }
        }
      }

    }

    /// @}


  private:

    vector<Scatter2DPtr> _mult;

    /// @name Multiplicities
    /// @{
    CounterPtr _cLight;
    CounterPtr _cCharm;
    CounterPtr _cBottom;
    /// @}

    /// @name Weights
    /// @{
    CounterPtr _wLight;
    CounterPtr _wCharm;
    CounterPtr _wBottom;
    /// @}

  };



  RIVET_DECLARE_ALIASED_PLUGIN(DELPHI_2000_S4328825, DELPHI_2000_I524693);

}