Multiparticle production and quantum chromodynamics

The theory of strong interactions, quantum chromodynamics (QCD), is quite successful in the prediction and description of main features of multiparticle production processes at high energies. The general perturbative QCD approach to these processes (mainly to e+e- -annihilation) is briefly formulated and its problems are discussed. It is shown that the analytical calculations at the parton level with the low-momentum cut-off reproduce experimental data on the hadronic final state in multiparticle production processes at high energies surprisingly accurately even though the perturbative expansion parameter is not very small. Moreover, it is important that the perturbative QCD has been able not only to describe the existing data but also to predict many bright qualitatively new phenomena.Comment: 30 pages, LATEX, 12 Figs available at www.ufn.ru; the review pap er to be published in Physics-Uspekhi 45 (5) (2002

Soft and hard jets in QCD

Multiplicity of sets of soft jets with energies ranging in some interval is determined. The possible role of collective effects is discussed.Comment: LATEX, 4 pages, no figures. Talk given at ISMD200