Explicit results for all orders of the epsilon expansion of certain massive and massless diagrams - art. no. 087701

An arbitrary term of the epsilon expansion of a dimensionally regulated off -shell massless one-loop three-point Feynman diagram is expressed in terms of log-sine integrals related to the polylogarithms. Using a magic connecti on between these diagrams and two-loop massive vacuum diagrams, the epsilon expansion of the latter is also obtained, for arbitrary values of the mass es. The problem of analytic continuation is also discussed.