Automorphic forms: a physicist's survey

Abstract

Motivated by issues in string theory and M-theory, we provide a pedestrian introduction to automorphic forms and theta series, emphasizing examples rather than generality.Comment: 22 pages, to appear in the Proceedings of Les Houches Winter School ``Frontiers in Number Theory, Physics and Geometry'', March 9-21, 2003; v2: minor changes and clarifications, section 3.5 on pure spinors has been rewritte