Analysis of the unbound spectrum of ${}^{12}$Li

Abstract

The unbound nucleus ${}^{12}$Li is evaluated by studying three-neutron one-proton excitations within the multistep shell model in the complex energy plane. It is found that the ground state of this system consists of an antibound $2^{-}$ state. A number of narrow states at low energy are found which ensue from the coupling of resonances in ${}^{11}$Li to continuum states close to threshold.

24 pages, 7 figures, 2 tables