Role of spin-orbit force in nuclear interactions

Abstract

The two-body problem (scattering and bound state) has been solved exactly by considering an extension of Yamaguchi's non-local separable potential so as to include a two-body spin-orbit force. The parameters of the potential have been determined by obtaining their exact relationships with the low-energy experimental data (scattering length, effective range, deuteron binding energy, quadrupole and magnetic moments and the D-state probability). It is found that in order to fit the data, particularly the magnetic moment, the strength of the spin-orbit force must be comparable to that of the tensor force. This potential has been applied to the evaluation of the spin-orbit energy splitting in the nuclei Ca⁴¹ and O¹⁷. It is found that the tensor force by itself gives the wrong sign of the splitting and that it is overcompensated by a large contribution (of the correct sign) arising from the two-body spin-orbit force.