Compton scattering off the deuteron at low and intermediate energies.

Abstract

Compton scattering off the deuteron is studied for photon energies up to about 100 MeV. This energy limit reflects the fact that only intermediate nucleon-nucleon (NN) states are considered. The NN propagator is constructed in a separable potential model, the parameters of which are fitted to describe the experimental NN scattering phase shifts. The problem of gauge invariance of the Compton amplitude is analyzed and the role of nonlocal currents is discussed. The low-energy theorem is satisfied. Our approach enables a direct calculation of both the real and imaginary part of the Compton scattering amplitude. It turns out that the strongest multipoles are dominated by the Born terms. Numerical results are compared to a previous dispersion theoretical calculation, and we find a strong disagreement between both calculations. We are led to conclude that certain assumptions made in the dispersion theoretical calculation are not justified.