Low-frequency photon scattering by nuclei

The low-frequency limit of elastic photon scattering by nuclei of spin zero is studied. The energy independent cross section (Thomson scattering) and the term quadratic in the frequency (Rayleigh scattering) are calculated in two ways: within classical electrodynamics and non-relativistic quantum mechanics. Particular emphasis is put on a correct description of the c.m. motion. The origin of the various retardation and polarizability terms is discussed. They are related to polarizabilities in static external fields. The existence of a dielectric polarizability is proposed which is the electric counterpart of diamagnetism. Orders of magnitudes of the expected effects are given. (13 refs).