Vanishing Gamow-Teller transition rate for A=14 and the nucleon-nucleon interaction in the medium - art. no. 067305

The problem of the near vanishing of the Gamow-Teller transition (GT) in th e A=14 system between the lowest J=0(+) T=1 and J=1(+) T=0 states is revisi ted. The model space is extended from the valence space (p(-2)) to the vale nce space plus all 2 (h) over bar omega excitations. The question is addres sed as to what features of the effective nucleon-nucleon interaction in the medium are required to obtain the vanishing GT strength in this extended s pace. It turns out that a combination of a realistic strength of the tensor force combined with a spin-orbit interaction which is enhanced as compared to the free interaction yields a vanishing GT strength. Such an interactio n can be derived from a microscopic meson exchange potential if the enhance ment of the small component of the Dirac spinors for the nucleons is taken into account. [S0556-2813(99)04112-6].