Cavity-induced damping and level shifts in a wide aperture spherical resonator

We calculate explicitly the space dependence of the radiative relaxation rates and associated level shifts for a dipole placed in the vicinity of the center of a spherical cavity with a large numerical apertureand a relatively low finesse. In particular, we give simple and useful analytic formulasfor these quantities, that can be used with arbitrary mirrors transmissions. The vacuum field in the vicinity of the center of the cavity is actually equivalent to the one obtained in a microcavity, and this scheme allows one to predict significant cavity QED effects.