rivet is hosted by Hepforge, IPPP Durham

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
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
// -*- 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:

    /// Constructor
    DELPHI_2000_S4328825()
      : Analysis("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;
    //@}
  };


  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(DELPHI_2000_S4328825);

}