Some Exact Results for Two-Loop Diagrams with Three and Four External Lines

Abstract

Evaluation of three- and four-point diagrams with massless internal particles and arbitrary external momenta is considered. Exact results for some two-loop diagrams (planar and non-planar three-point contributions and the "double box" diagram) are obtained in terms of polylogarithms.

Comments: To appear in Proc. VII Intern. Workshop "High Energy Physics and Quantum Field Theory" (Sochi, Russia, October 1992), Yad.Fiz., v.56, No.11, p.172-179 (November 1993)