A study of charged particle multiplicities in hadronic decays of the Z0

We present an analysis of multiplicity distributions of charged particles produced in Z0 hadronic decays. The results are based on the analysis of 82941 events collected within 100 MeV of the Z0 peak energy with the OPAL detector at LEP. The charged particle multiplicity distribution, corrected for initial-state radiation and for detector acceptance and resolution, was found to have a mean =21.40±0.02(stat.)±0.43(syst.) and a dispersion D=6.49±0.02(stat.)±0.20(syst.). The shape is well described by the Lognormal and Gamma distributions. A negative binomial parameterisation was found to describe the shape of the multiplicity distribution less well. A comparison with results obtained at lower energies confirms the validity of KNO(-G) scaling up to LEP energies. A separate analysis of events with low sphericity, typically associated with two-jet final states, shows the presence of features expected for models based on a stochastic production mechanism for particles. In all cases, the features observed in the data are well described by the Lund parton shower model JETSET. (orig.)