Suppression of Core Polarization in Halo Nuclei

Halo nuclei are studied using a G-matrix interaction derived from the Paris and Bonn potentials and employing a two-frequency shell model approach. It is found that the core-polarization effect is dramatically suppressed in such nuclei. Consequently, the effective interaction for halo nucleons is almost entirely given by the bare G matrix alone, which presently can be evaluated with a high degree of accuracy. The experimental pairing energies between the two halo neutrons in {sup 6}He and {sup 11}Li nuclei are satisfactorily reproduced by our calculation. It is suggested that the fundamental nucleon-nucleon interaction can be probed in a clearer and more direct way in halo nuclei than in ordinary nuclei. {copyright} {ital 1997} {ital The American Physical Society}