Irregularities in nuclear radii at magic numbers

The influence of magic numbers on nuclear radii is investigated via the Hartree-Fock-Bogolyubov calculations and available experimental data. With the $\ensuremath{\ell}s$ potential including additional density dependence suggested from the chiral effective-field theory, kinks are universally predicted at the $jj$-closed magic numbers and antikinks (i.e., inverted kinks) are newly predicted at the $\ensuremath{\ell}s$-closed magic numbers, both in the charge radii and in the matter radii along the isotopic and isotonic chains where nuclei stay spherical. These results seem consistent with the kinks of the charge radii observed in Ca, Sn, and Pb and the antikink in Ca. The kinks and the antikinks could be a peculiar indicator for magic numbers, discriminating $jj$ closure and $\ensuremath{\ell}s$ closure.