  The formalism based on correlated basis functions and the cluster expansion
technique has been recently employed to derive an effective interaction from a
realistic nuclear hamiltonian. To gauge the reliability of this scheme, we
perform a systematic comparison between the results of its application to the
Fermi hard-sphere system and the predictions obtained from low-density
expansions, as well as from other many-body techniques. The analysis of a
variety of properties, including the ground state energy, the effective mass
and the momentum distribution, shows that the effective interaction approach is
remarkably accurate, thus suggesting that it may be employed to achieve a
consistent description of the structure and dynamics of nuclear matter in the
density region relevant to astrophysical applications.
