Closed-shell properties of ${}^{24}\mathrm{O}$ with ab initio coupled-cluster theory

We present a microscopic calculation of spectroscopic factors for neutron and proton removal from ${}^{24}\mathrm{O}$ using the coupled-cluster method and a state-of-the-art chiral nucleon-nucleon interaction at next-to-next-to-next-to-leading order. To account for the coupling to the scattering continuum we use a Berggren single-particle basis that treats bound, resonant, and continuum states on an equal footing. We report neutron removal spectroscopic factors for the ${}^{23}\mathrm{O}$ states $J^{\pi }=1/2^{+}$, $5/2^{+}$, $3/2^{-}$, and $1/2^{-}$ and proton removal spectroscopic factors for the ${}^{23}\mathrm{N}$ states $1/2^{-}$ and $3/2^{-}$. Our calculations support the accumulated experimental evidence that ${}^{24}\mathrm{O}$ is a closed-shell nucleus.

Figure 1

Normalized SFs plotted against $\hslash \omega$ for $J^{\pi }=1/2^{+}$ and $5/2^{+}$ one-neutron removal from ${}^{24}\mathrm{O}$. The continuum states included in the Berggren-basis calculation (GHF) lead only to a small reduction compared with the harmonic oscillator values (OHF). The dependence on the oscillator spacing $\hslash \omega$ is very weak in both calculations. The inclusion of the continuum structure also gives a small, but visible, improvement in the $\hslash \omega$ dependence.

Figure 2

Normalized SFs plotted against $\hslash \omega$ for the negative parity states $J^{\pi }=1/2^{-}$ and $3/2^{-}$ in one-proton ($\pi$) and one-neutron ($\nu$) removal from ${}^{24}\mathrm{O}$.