Correlations in the Charged-Particle Multiplicity Distribution

Abstract

In this thesis, we perform an analysis on e+e- hadronic Z decays recorded in 1994 and 1995 by the L3 detector of LEP at center-of-mass energy corresponding to the Z mass. The analysis is performed in parallel for all hadronic events and for selected b-quark and light-quark events. The distribution of two variables, the charged-particle multiplicity and the inclusive charged-particle momentum are measured, from which all the analysis is carried out. From the measurement of the charged-particle multiplicity distribution, it is possible to extract information concerning the dynamics of the interaction. Using moments, one can obtain informations on particle correlation. We measure the Hq moments of the charged-particle multiplicity distribution which give the relative amount of genuine q-particle correlation order q. An oscillatory pattern is observed when the H_q moments are plotted versus the order q. Comparisons with different theoretical approaches are discussed.