Algebraic Aspects of Matrix Theory on T^d

Abstract

We study the exceptional U duality group $E_d$ of M-theory compactified on a d-torus and its representations using Matrix theory. We exhibit the $E_d$ structure and show that p-branes wrapped or unwrapped around the longitudinal direction form representations of the U duality group together with other, more mysterious, states.

28 pages, harvmac, note added in version published in NPB: 8-brane naturally completes the weyl multiplets into E_d representations