Anomalous behavior of the first excited 0${}^{+}$ state in $N\approx Z$ nuclei

Abstract

A study of the energies of the first excited $0^{+}$ states in all even-even $Z$ $\ge$ 8 nuclei reveals an anomalous behavior in some nuclei with $N$ = $Z$, $Z$ $\pm$ 2. We analyze these irregularities in the framework of the shell model. It is shown that proton-neutron correlations play an important role in this phenomenon.

Comments: 4 pages, 5 figures