Rivet analyses

title: OPAL_2002_I601225

Charged particle multiplicities in heavy and light quark initiated events above the $Z^0$ peak

Experiment: OPAL (LEP 2)

Inspire ID: 601225

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B550 (2002) 33-46 - hep-ex/0211007

Beams: e+ e-

Beam energies: (65.0, 65.0); (68.0, 68.0); (80.5, 80.5); (86.0, 86.0); (91.5, 91.5); (94.5, 94.5); (96.0, 96.0); (98.0, 98.0); (100.0, 100.0); (101.0, 101.0); (103.0, 103.0)GeV

Run details: - Hadronic Z decay events generated above the Z pole

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. The data is from the LEP running periods between 1995 and 2000.

Source code:OPAL_2002_I601225.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/ChargedFinalState.hh"

include

define I_KNOW_THE_INITIAL_QUARKS_PROJECTION_IS_DODGY_BUT_NEED_TO_USE_IT

include "Rivet/Projections/InitialQuarks.hh"

namespace Rivet {

/// @brief OPAL multiplicities at various energies /// /// @author Peter Richardson class OPAL_2002_I601225 : public Analysis { public:

RIVET_DEFAULT_ANALYSIS_CTOR(OPAL_2002_I601225);


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

void init() {
  // Projections
  declare(Beam(), "Beams");
  declare(ChargedFinalState(), "CFS");
  declare(InitialQuarks(), "IQF");

  // Histograms
  book(_hLight, 1, 1, 3);
  book(_hCharm, 1, 1, 2);
  book(_hBottom, 1, 1, 1);
}


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: _hLight->fill(int(sqrtS()), numParticles); break;
    case 4: _hCharm->fill(int(sqrtS()), numParticles); break;
    case 5: _hBottom->fill(int(sqrtS()), numParticles); break;
  }
}


void finalize() {
  BinnedEstimatePtr<int> hDiff;
  book(hDiff, 1, 1, 4);
  for (unsigned int ix = 0; ix < hDiff->numBins(); ++ix) {
    if (_hBottom->bin(ix + 1).numEntries() > 0 && _hLight->bin(ix + 1).numEntries() > 0) {
      double val = _hBottom->bin(ix + 1).mean(2) - _hLight->bin(ix + 1).mean(2);
      double err = sqrt(sqr(_hBottom->bin(ix + 1).stdErr(2)) + sqr(_hLight->bin(ix + 1).stdErr(2)));
      hDiff->bin(ix + 1).setVal(val);
      hDiff->bin(ix + 1).setErr(err);
    }
  }
}

/// @}

private:

/// @name Multiplicities
/// @{
BinnedProfilePtr<int> _hLight, _hCharm, _hBottom;
/// @}

};

RIVET_DECLARE_ALIASED_PLUGIN(OPAL_2002_I601225, OPAL_2002_S5361494);

} ```

Aliases: - OPAL_2002_S5361494