  We propose a formulation of 11-dimensional M-theory in terms of five-branes
with closed strings on their world-volume. We use this description to construct
the complete spectrum of BPS states in compactifications to six and five
dimensions. We compute the degeneracy for fixed charge and find it to be in
accordance with U-duality (which in our formulation is manifest in six
dimensions) and the statistical entropy formula of the corresponding black
hole. We also briefly comment on the four-dimensional case.

High Energy Physics - Theory