Coulomb Energy ofHe3and Charge Symmetry of Nuclear Forces

The Coulomb energy of ${\mathrm{He}}^3$ has been calculated using separable potentials with a repulsive term. The calculated value is in close agreement with the ${\mathrm{H}}^3$-${\mathrm{He}}^3$ binding-energy difference. An expected 3-6% decrease, brought about mainly by the inclusion of a tensor term, can be explained by charge asymmetry due to $\eta -\pi$ and $\rho -\omega -\varphi$ mixing, provided one takes $\frac{g_{\rho }}{g_{\omega }}>0\mathrm{}$. This also yields $a_{\mathrm{nn}}-a_{\mathrm{pp}}>0\mathrm{}$, which is required by the present experimental situation, in contrast to $a_{\mathrm{nn}}-a_{\mathrm{pp}}\sim 1.4$ fm obtained by earlier authors with $\frac{g_{\rho }}{g_{\omega }}<0\mathrm{}$.