Photonuclear Sum Rule forHe3andH3

The enhancement factor $\kappa$ in the electric dipole sum rule for $A=3\mathrm{}$ nuclei is calculated using the bound-state wave function obtained from a solution of the Faddeev equations with the Reid soft-core two-nucleon potential. We find $\kappa =0.8\mathrm{}$ for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$. The $S-D$ interference terms are found to be very important. Our result is consistent with experimental data for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$.