  The Mott transition in a multi-orbital Hubbard model involving subbands of
different widths is studied within the dynamical mean field theory. Using the
iterated perturbation theory for the quantum impurity problem it is shown that
at low temperatures inter-orbital Coulomb interactions give rise to a single
first-order transition rather than a sequence of orbital selective transitions.
Impurity calculations based on the Quantum Monte Carlo method confirm this
qualitative behavior. Nevertheless, at finite temperatures, the degree of
metallic or insulating behavior of the subbands differs greatly. Thus, on the
metallic side of the transition, the narrow band can exhibit quasi-insulating
features, whereas on the insulating side the wide band exhibits pronounced
bad-metal behavior. This complexity might partly explain contradictory results
between several previous works.
