Quantum and Coulomb repulsion effects on the bubble structures in ${}^{204,206}$Hg

Abstract

The decreasing proton and charge densities from around 5.0 fm towards the center of ${}^{204,206}$Hg are investigated by a covariant density functional theory at the beyond mean-field level.The charge-density difference between ${}^{208}$Pb and ${}^{204}$Hg is improved significantly and a central depression is still visible in the ground-state density of ${}^{204,206}$Hg when the dynamic correlations associated with symmetry restoration and shape mixing are taken into account. For the $0_2^{+}$ and $2_1^{+}$ excited states of ${}^{204,206}$Hg, their densities remain decreasing from 5.0 fm to around 2.0 fm, but become flat in the interior region. The results show that the bubble structure in ${}^{204,206}$Hg within 2.0 fm is mainly attributed to the quantum effect, while that beyond 2.0 fm is formed by the Coulomb repulsion.

Comments: 7 pages, 7 figures, submitted to PRC