Proton-neutron multiplets in exotic 134Sb : Testing the shell-model effective interaction

The experimental level structure of $^{134}\mathrm{Sb}$ is compared with the results of a shell-model calculation in which the two-body matrix elements of the effective interaction have been derived from the CD-Bonn nucleon-nucleon potential. The experimental data, including the very low lying first-excited ${1}^{\ensuremath{-}}$ state, are remarkably well reproduced by the theory. The results of this paper complement those of our previous studies on $^{135}\mathrm{Sb}$ and $^{134}\mathrm{Sn}$, showing that our effective interaction is well suited to describe $^{132}\mathrm{Sn}$ neighbors beyond $N=82$. The various terms that contribute to the matrix elements of the proton-neutron effective interaction are examined and their relative importance is evidenced.