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.

Decamp, D., Deschizeaux, B., Goy, C., Lees, J., Minard, M., Alemany, R., et al. (1991). Measurement of the charged particle multiplicity distribution in hadronic Z decays. PHYSICS LETTERS. SECTION B, 273(1-2), 181-192 [10.1016/0370-2693(91)90575-B].

Measurement of the charged particle multiplicity distribution in hadronic Z decays

CARPINELLI, Massimo;
1991

Abstract

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.
Articolo in rivista - Articolo scientifico
E+E ANNIHILATION; PETRA ENERGIES; PP COLLISIONS; MONTE-CARLO; FRAGMENTATION; QUARK;
English
1991
273
1-2
181
192
none
Decamp, D., Deschizeaux, B., Goy, C., Lees, J., Minard, M., Alemany, R., et al. (1991). Measurement of the charged particle multiplicity distribution in hadronic Z decays. PHYSICS LETTERS. SECTION B, 273(1-2), 181-192 [10.1016/0370-2693(91)90575-B].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/390450
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