  We study the single-band Hubbard model in the presence of a large spatially
uniform electric field out of equilibrium. Using the Keldysh nonequilibrium
formalism, we solve the problem using perturbation theory in the Coulomb
interaction U. We present numerical results for the charge current, the total
energy of the system and the double occupancy on an infinite-dimensional
hypercubic lattice with nearest-neighbor hopping. The system is isolated from
an external bath and is in the paramagnetic state. We show that an electric
field pulse can drive the system to a steady nonequilibrium state, which does
not evolve into a thermal state. We compare results obtained within
second-order perturbation theory (SOPT), self-consistent second-order
perturbation theory (SCSOPT) and iterated perturbation theory (IPT). We also
discuss the importance of initial conditions for a system which is not coupled
to an external bath.
