Nuclear shape staggering of neutron-deficient Au and kink structure of Pb isotopes

In this study, we examine the abnormal odd-even shape staggering (OES) behavior of nuclear charge radii of neutron-deficient gold (Au) isotopes, which has recently been confirmed by advanced laser techniques. To understand the nuclear structure underlying this phenomenon, we apply the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc). Our results find that the shape staggering can be attributed to nuclear shape transition in the Au isotopes. The gold isotopic chain exhibits significant changes in ground state deformation around N = 98 ~ 100 region and $N =$ 108. The abrupt decrease in the relative changes in mean-squared charge radii (δ < r² >) turns out to originate from sudden transitions from prolate deformation to oblate deformation. We elucidate the nuclear shape staggering by analyzing the evolution of occupation probability for single-particle states. Finally, the abrupt kink structure in the nuclear charge radius of lead (Pb) isotopes near the $N =$ 126 shell is also investigated and reproduced quite well.