The high polarizability of light halo nuclei close to the neutron drip-line play a prominent role in the nature of pairing correlations among the neutrons forming the halo. Indeed, exotic features of the nuclear spectra of these systems, such as parity inversion, can be quantitatively accounted for taking into account the coupling of valence neutrons with low-lying collective modes.
A unified nuclear-structure-direct-reaction theory provides the framework to subject these considerations to experimental verification. To this respect, recent data resulting from studies of two-nucleon transfer reaction on 11Li provides direct experimental evidence of the role of collective vibrations in the structure of the ground state of this halo nucleus.
