Three-body model calculation of the 2$^+$ state in $^{26}$O

TL;DR

This paper models the 2$^+$ excited state in the unbound nucleus $^{26}$O using a three-body approach that includes continuum effects and dineutron correlations, providing insights into its energy and spectral structure.

Contribution

It introduces a three-body model calculation that accurately accounts for continuum effects and dineutron correlations in $^{26}$O, offering a detailed understanding of its excited states.

Findings

The 2$^+$ state energy is calculated as 1.354 MeV.

The energy shift indicates a typical spectrum with short-range pairing.

The model suggests the spectrum is well described by pairing interactions.

Abstract

We discuss the energy of the excited 2$^+$ state in the unbound nucleus $^{26}$O using the three-body model of $^{24}$O+$n$+$n$. This model fully takes into account the continuum effects as well as the dineutron correlation of the valence neutrons. The present calculation yields the energy of 1.354 MeV, which is slightly smaller than the unperturbed energy, 1.54 MeV. The energy shifts for the ground and the 2$^+$ states with respect to the unperturbed energy suggest that 0$^+$ and the 2$^+$ states in $^{26}$O show a typical spectrum well described by a short-range pairing interaction acting on two valence nucleons in the same orbit.