  The pairing anti-halo effect is a phenomenon that a pairing correlation
suppresses a divergence of nuclear radius, which happens for single-particle
states with orbital angular momenta of $l$ = 0 and 1 in the limit of vanishing
binding energy. While this effect has mainly been discussed in terms of
Hartree-Fock-Bogoliubov (HFB) theory, we here use a three-body model and
provide its new intuitive concept as a localized wave packet for a
quasi-particle, that is, a coherent superposition of a weakly bound and
continuum wave functions due to a pairing interaction. We show that the
one-particle density in the three-body model can be directly expressed with
such quasi-particle wave functions, which have a close analog to wave functions
in the HFB approximation.
