Ground state inversions in hole nuclei near Sn 132 driven by the monopole interaction

The neutron-rich nuclei to the southwest of $^{132}\mathrm{Sn}$ are studied comprehensively by large-scale, shell-model calculations with the extended pairing plus multipole-multipole force (EPQQM) model. A regular correlation driven by the monopole interaction between the neutron orbits ${h}_{11/2}$ and ${d}_{3/2}$ is found in this nuclear region for different isotonic chains with $N=79,80,81$. The ground-state inversions from $^{130}\mathrm{In}$ $(^{129}\mathrm{Cd})$ to $^{128}\mathrm{In}$ $(^{127}\mathrm{Cd})$ seen experimentally are well described for the first time by this regular correlation. The regular correlation in different isotonic chains is also supported by a systematic comparison between the observed spectra of $^{126}\mathrm{Ag}$ and $^{128}\mathrm{In}$, and further confirmed by the investigation of isomeric states of $^{126}\mathrm{Pd}$, $^{128}\mathrm{Cd}$, and $^{129}\mathrm{In}$ the in $N=80$ isotonic chain. This regular correlation in different isotonic chains should provide useful guidance for further experiments in this region of nuclei.