Mean-Field Description of Cooperative Scattering by Atomic Clouds

We present analytic expressions for the scattering of light by an extended atomic cloud. We obtain the solution for the mean-field excitation of different atomic spherical distributions driven by an uniform laser, including the initial build-up, the steady-state and the decay after the laser is switched off. We show that the mean-field model does not describe subradiant scattering, due to negative interference of the photons scattered by $N$ discrete atoms.