Exchange effects in photon scattering off the deuteron

Abstract

Detailed calculations of elastic photon-deuteron scattering cross sections for photon energies up to about the π-production threshold are presented. The scattering amplitude is decomposed into scalar, vector and tensor polarizabilities for the various electric and magnetic multipole combinations. This includes a general multipole expansion of the two-photon operator. The imaginary part of the polarizabilities is determined from the contribution to the total cross section using the optical theorem. The real part is then obtained from dispersion relations. Special emphasis is laid on the discussion of exchange effects for both the resonance and the two-photon amplitude. These affect strongly the resonance amplitude whereas for the two-photon amplitude we find only a small effect beyond the important low-energy limit. Another important result is the large vector polarizability at higher energies related to the optical activity of the deuteron.