Calculation of the spectrum of 12Li by using the multistep shell model method in the complex energy plane

TL;DR

This paper calculates the spectrum of the unbound nucleus 12Li using a multistep shell model in the complex energy plane, revealing the nature of its ground and excited states.

Contribution

It introduces a novel application of the multistep shell model in the complex energy plane to analyze unbound nuclei like 12Li.

Findings

Ground state is an antibound 1/2+ state.

Only specific states are physically meaningful resonances.

Identifies excited states as 1/2- and 5/2+.

Abstract

The unbound nucleus $^{12}$Li is evaluated by using the multistep shell model in the complex energy plane assuming that the spectrum is determined by the motion of three neutrons outside the $^9$Li core. It is found that the ground state of this system consists of an antibound $1/2^+$ state and that only this and a $1/2^-$ and a $5/2^+$ excited states are physically meaningful resonances.