The nature of ⁹N and ⁹He low-lying states

A recent experiment provided the first evidence for ⁹N, a 5p emitter [1]. Since ⁹N lies well beyond the proton dripline, questions were raised as to the nature of its states and the states of its mirror nucleus, ⁹He. Experimental data for ⁹N suggests that there is a possible 1/2⁺ state and a 1/2^- resonance state at higher energy. Initial comparisons with the mirror nucleus ⁹He suggested that this 1/2⁺ was a resonance [2,3], thus the ground state for both nuclei might be a resonance, yet both works may have introduced some artificial binding to stabilize the results. According to our Gamow Shell Model calculations, the 1/2⁺ state of ⁹He is a virtual state while in ⁹N the 1/2⁺ is a threshold resonant state, similar to the ground state of ¹⁰N [4].