MEASUREMENTS OF THE CHARGED-PARTICLE MULTIPLICITY DISTRIBUTION IN RESTRICTED RAPIDITY INTERVALS

Charged particle multiplicity distributions have been measured with the ALEPHdetector in restricted rapidityintervals |Y| ≤0.5, 1.0, 1.5, 2.0 along the thrust axis and also without restrictionon rapidity. The distribution for the full range can be parametrized by a log-normal distribution. For smaller windows one finds a more complicated structure, which is understood to arise from perturbative effects. The negative-binomial distributionfails to describe the data both with and without the restrictionon rapidity. The JETSET model is found to describe all aspects of the data while the width predicted by HERWIG is in significant disagreement.