Rivet analyses

title: SLD_1996_I422172

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

Experiment: SLD (SLC)

Inspire ID: 422172

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett.B386:475-485,1996 - hep-ex/9608008

Beams: e+ e-

Beam energies: (45.6, 45.6)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 the $Z^0$ mass.

Source code:SLD_1996_I422172.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/ChargedFinalState.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/Hemispheres.hh"

include "Rivet/Projections/ParisiTensor.hh"

include "Rivet/Projections/Sphericity.hh"

include "Rivet/Projections/Thrust.hh"

include

define I_KNOW_THE_INITIAL_QUARKS_PROJECTION_IS_DODGY_BUT_NEED_TO_USE_IT

include "Rivet/Projections/InitialQuarks.hh"

namespace Rivet {

/// @brief SLD multiplicities at mZ /// /// @author Peter Richardson class SLD_1996_I422172 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(SLD_1996_I422172);


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

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

  book(_h_bottom, 1, 1, 1);
  book(_h_charm, 2, 1, 1);
  book(_h_light, 3, 1, 1);

  book(_weightLight, "_weightLight");
  book(_weightCharm, "_weightCharm");
  book(_weightBottom, "_weightBottom");

  book(scatter_c, 4, 1, 1);
  book(scatter_b, 5, 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:
      _weightLight->fill();
      _h_light->fill(_h_light->bin(1).xMid(), numParticles);
      break;
    case 4:
      _weightCharm->fill();
      _h_charm->fill(_h_charm->bin(1).xMid(), numParticles);
      break;
    case 5:
      _weightBottom->fill();
      _h_bottom->fill(_h_bottom->bin(1).xMid(), numParticles);
      break;
  }
}


void multiplicity_subtract(const Histo1DPtr first, const Histo1DPtr second, Estimate1DPtr& estimate) {
  const auto diff = first->bin(1) - second->bin(1);
  estimate->bin(1).set(diff.sumW(), diff.errW());
}


void finalize() {
  if (_weightBottom->val()) scale(_h_bottom, 1. / *_weightBottom);
  if (_weightCharm->val()) scale(_h_charm, 1. / *_weightCharm);
  if (_weightLight->val()) scale(_h_light, 1. / *_weightLight);

  multiplicity_subtract(_h_charm, _h_light, scatter_c);
  multiplicity_subtract(_h_bottom, _h_light, scatter_b);
}

/// @}

private:

/// Histograms
Estimate1DPtr scatter_c, scatter_b;
Histo1DPtr _h_bottom, _h_charm, _h_light;

/// Weights
CounterPtr _weightLight, _weightCharm, _weightBottom;

};

RIVET_DECLARE_ALIASED_PLUGIN(SLD_1996_I422172, SLD_1996_S3398250);

} ```

Aliases: - SLD_1996_S3398250