  We studied the Fermi and Gamow-Teller responses of cold symmetric nuclear
matter within a unified dynamical model, suitable to account for both short-
and long-range correlation effects. The formalism of correlated basis functions
has been used to construct two-body effective interactions and one-body
effective weak operators. The inclusion of the three-body cluster term allowed
for incorporating in the effective interaction a realistic model of three-
nucleon forces, namely the UIX potential. Moreover, the sizable unphysical
dependence of the effective weak operator is removed once the three-body
cluster term is taken into account.
