Evolution of average multiplicities of quark and gluon jets - art. no. 074009

The energy evolution of the average multiplicities of quark and gluon jets is studied in perturbative QCD. Higher order (3NLO) terms in the perturbati ve expansion of equations for the,generating functions are found. First and second derivatives of average multiplicities are calculated. The mean mult iplicity of gluon jets is larger than that of quark jets and evolves more r apidly with energy. It is shown which quantities are most sensitive to high er order perturbative and nonperturbative corrections. We define the energy regions where the corrections to different quantities are important. The l atest experimental data are discussed.