Application of a coordinate space method for the evaluation of lattice Feynman diagrams in two dimensions

Abstract

We apply a new coordinate space method for the evaluation of lattice Feynman diagrams suggested by Lüscher and Weisz to field theories in two dimensions. Our work is to be presented for the theories with massless propagators. The main idea is to deal with the integrals in position space by making use of the recursion relation for the free propagator $G(x)$ which allows to compute the propagator recursively by its values around origin. It turns out that the method is very efficient and gives very precise results. We illustrate the technique by evaluating a number of two- and three-loop diagrams explicitly.

Comments: 25 pages, Latex, 2 figures, revised by discussing some points in more detail and correcting a few typos