Renormalons: technical introduction

Abstract

The large-beta_0 limit of QCD is discussed, with the emphasize on simple technical methods of calculating various quantities at the order 1/\beta_0. Many examples, mainly from heavy quark physics, are considered. Some QCD results based on renormalization group (and not restricted to the large-\beta_0 limit) are also discussed.

Comments: 40 pages, 18 eps figures included