Effective field theory description of halo nuclei

Understand

Nuclear halos emerge as new degrees of freedom near the neutron and proton driplines.

• They consist of a core and one or a few nucleons which spend most of their time in the classically-forbidden region outside the range of the interaction.
• Individual nucleons inside the core are thus unresolved in the halo configuration, and the low-energy effective interactions are short-range forces between the core and the valence nucleons.
• Similar phenomena occur in clusters of $^4$He atoms, cold atomic gases near a Feshbach resonance, and some exotic hadrons.