The Minimal Unitary Representation of E_8(8)

We give a new construction of the minimal unitary representation of the exceptional group E8(8) on a Hilbert space of complex functions in 29 variables. Due to their manifest covariance with respect to the E7(7) subgroup of E8(8) our formulas are simpler than previous realizations, and thus well suited for applications in supergravity and superstring theory. One possible application arises in the context of the conformal quantum mechanics description of extremal black holes in maximally extended supergravity.