${}^{11}$Li and ${}^6$He are described as three-body systems using different approaches. We compare our technique, based on a density-dependent, cutoff, contact interaction between the valence neutrons, with a Faddeev approach which is based on realistic interactions. The ground state properties of a weakly bound two-neutron halo are described fairly well once the contact interaction has been adjusted and calibrated to produce a realistic scattering length and effective range.

• Received 5 May 1997

DOI:https://doi.org/10.1103/PhysRevC.56.3054