Ab Initio Computation of the ¹⁷F Proton Halo State and Resonances in A=17 Nuclei

We perform coupled-cluster calculations of the energies and lifetimes of single-particle states around the doubly magic nucleus ¹⁶O based on chiral nucleon-nucleon interactions at next-to-next-to-next-to-leading order. To incorporate effects from the scattering continuum, we employ a Gamow-Hartree-Fock basis. Our calculations for the J^π=1/2⁺ proton halo state in ¹⁷F and the 1/2⁺ state in ¹⁷O agree well with experiment, while the calculated spin-orbit splitting between 5/2⁺ and 3/2⁺ states is too small due to the lack of three-nucleon forces. Continuum effects yield a significant amount of additional binding energy for the 1/2⁺ and 3/2⁺ states in ¹⁷O and ¹⁷F.