High-spin intruder states in thefp-shell nuclei and isoscalar proton-neutron correlations

Abstract

We perform a systematic theoretical analysis of fully-aligned, high-spin ${f}_{7/2}^{n}$ seniority isomers and ${d}_{3/2}^{\ensuremath{-}1}{f}_{7/2}^{n+1}$ intruder states in the $A~44$ nuclei from the lower-$\mathit{fp}$ shell. The configuration-interaction calculations, based on the nuclear shell model, are performed in the full $\mathit{sdfp}$ configuration space allowing $1p$-$1h$ cross-shell excitations. The density functional theory calculations are carried out within the self-consistent Hartree-Fock approach with the Skyrme energy functional that reproduces empirical Landau parameters. While there is a nice agreement between experimental and theoretical relative energies of fully-aligned states in $N>Z$ nuclei, this is no longer the case for the $N=Z$ systems. The remaining deviation from the data is attributed to the isoscalar proton-neutron correlations. It is also demonstrated that the Coulomb corrections at high spins noticeably depend on the choice of the energy density functional.