Oscillations of mainly surface character (S=0 modes) give rise, in atomic nuclei, to an attractive (induced) pairing interaction, while spin (S=1) modes of mainly volume character generate a repulsive interaction, the net effect being an attraction which accounts for a sizeable fraction of the experimental pairing gap. Suppressing the particle-vibration coupling mediated by the proton degrees of freedom, i.e., mimicking neutron matter, the total surface plus spin-induced pairing interaction becomes repulsive.
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