UNIVERSAL ASPECTS OF EFIMOV STATES AND LIGHT HALO NUCLEI

The parametric region in the plane defined by the ratios of the energi es of the subsystems and the three-body ground state, in which Efimov states can exist, is determined. We use a renormalizable model that gu arantees the general validity of our results in the context of short-r ange interactions. The experimental data for one-and two-neutron separ ation energies, implies that among the halo nuclei candidates, only C- 20 has a possible Efimov state, with an estimated energy less than 14 KeV below the scattering threshold.