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

We perform coupled-cluster calculations of the energies and lifetimes of single-particle states around the doubly magic nucleus O-16 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(pi) = 1/2(+) proton halo state in F-17 and the 1/2(+) state in O-17 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 O-17 and F-17.