Effect of the Tensor Force on the Charge Exchange Spin-Dipole Excitations of 208Pb

The charge exchange spin-dipole (SD) excitations of Pb-208 are studied by using a fully self-consistent Skyrme Hartree-Fock plus random phase approximation formalism which includes the tensor interaction. It is found, for the first time, that the tensor correlations have a unique, multipole-dependent effect on the SD excitations; that is, they produce a softening of 1(-) states, but a hardening of 0(-) and 2(-) states. This paves the way to a clear assessment of the strength of the tensor terms. We compare our results with a recent measurement, showing that our choice of tensor terms improves the agreement with experiment. The robustness of our results is supported by the analytic form of the tensor matrix elements.