Electron-positron interactions

The author introduces the total cross section sigma for e/sup +/e/sup -/ annihilation, discusses some simple models, which predict the asymptotic behaviour of sigma , and relates sigma to the vacuum polarization, which has been measured recently in e/sup +/e/sup -/ to mu /sup +/ mu /sup -/. He explains the kinematics and basic definitions of one-particle distributions and discusses their relation to the corresponding process in inelastic electron scattering. The cross section for one-particle detection is calculated under the assumption of scaling. He gives an introduction to two-particle production for arbitrary spins and parities of the two particles. The general structure of the two-particle current matrix element is worked out in the c.m. system. This is used to calculate some examples, which are of importance for the discussion of recent experimental data for many pion production coming from Adone. Finally he gives some conclusions and outlines the general importance of the study of many- pion channels also at higher energies. (33 refs).