Measurement of the charged particle multiplicity distribution in hadronic Z decays
Collaboration
12 pages
Published in:
- Phys.Lett.B 273 (1991) 181-192
- Published: 1991
Report number:
- CERN-PPE-91-159
Experiments:
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Abstract: (Elsevier)
The charged particle multiplicity distribution of hadronic Z decays was measured on the peak of the Z resonance using the ALEPH detector at LEP. Using a model independent unfolding procedure the distribution was found to have a mean 〈 n 〉=20.85±0.24 and a dispersion D =6.34±0.12. Comparison with lower energy data supports the KNO scaling hypothesis in the energy range s =29−91.25 GeV. At s =91.25 GeV the shape of the multiplicity distribution is well described by a log-normal distribution, as predicted from a cascading model for multi-particle production. The same model also successfully describes the energy dependence of the mean and width of the multiplicity distribution. A next-to-leading order QCD prediction in the framework of the modified leading-log approximation and local parton-hadron duality is found to fit the energy dependence of the mean but not the width of the charged multiplicity distribution, indicating that the width of the multiplicity distribution is a sensitive probe for higher order QCD or non-perturbative effects.- electron positron: colliding beams
- colliding beams: electron positron
- electron positron: annihilation
- annihilation: electron positron
- Z0: electroproduction
- electroproduction: Z0
- Z0: nonleptonic decay
- nonleptonic decay: Z0
- charged particle: multiplicity
- multiplicity: spectrum
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