SS-HORSE extension of the no-core shell model: Application to resonances in He 7

Abstract

Theoretical ab initio studies of resonances in the unbound He7 nucleus are presented. We perform no-core shell-model calculations with NN interactions Daejeon16 and JISP16 and utilize the SS-HORSE method to calculate the S matrix for two-body channels n+He6 and n+He∗6 with He6 respectively in the ground and excited 2+ states as well as for the four-body democratic decay channel He4+n+n+n. The resonant energies and widths are obtained by numerical location of the S-matrix poles. We describe all experimentally known He7 resonances and suggest an interpretation of an observed wide resonance of unknown spin-parity. © 2022 American Physical Society.