Two-body effects in deuteron photoabsorption sum rules

The effect of the two-body charge and current densities is considered in the deuteron photoabsorption sum rules. The modifications induced in the Siegert form of the $E1\mathrm{}$ operator give rise to an enhancement factor $k_2\simeq 0.2$ over the Thomas-Reiche-Kuhn value of the integrated cross section ${\sigma }_0$. The bremsstrahlung-weighted cross section ${\sigma }_{-1\mathrm{}}\mathrm{}\left(E1\mathrm{}\right)\mathrm{}$ is found practically unchanged with respect to its value in impulse approximation, while ${\sigma }_{-1\mathrm{}}\mathrm{}\left(M1\mathrm{}\right)\mathrm{}$ shows a 30% increase. The calculations are performed with hard-core, soft-core, and super-soft-core potentials. The dependence on the potential model is small for ${\sigma }_0$ and quite negligible for ${\sigma }_{-1\mathrm{}}$.