Tensor correlations and evolution of single-particle energies in medium-mass nuclei

We analyze the evolution of the spin-orbit splittings in the Ca isotopes and in the N=28 isotones. We also focus on the reduction of the spin-orbit splittings associated with f and p orbits from Ca-48 to Ar-46. We conclude that adding the tensor contribution can qualitatively explain in most cases the empirical trends, whereas this is not the case if one simply employs existing Skyrme parametrizations without the tensor force.