No-Core Shell Model and Continuum Spectrum States of Light Nuclei

Shell model is a conventional tool for nuclear structure studies. Some states obtained in such studies belong to the continuum nuclear spectrum, i.e. their energies are above nuclear dissociation thresholds. These energies are conventionally associated with the energies of resonances in respective nuclear systems that is justified only in the case of narrow resonances. In this contribution, we develop a J-matrix inverse scattering approach which can be used for the analysis of scattering phase shifts and generating eigenenergies in the continuum directly related to the ones obtained in shell model applications in a given model model space and with a given value of the oscillator basis parameter ~Ω. This relationship is of a particular interest in the cases when a nuclear many-body system does not have a resonant state or the resonance is broad and its energy can differ significantly from the shell model eigenstate. After discussing the Jmatrix inverse scattering technique, we apply it to the analysis of nα and pα scattering. The results are compared with the No-core Shell Model calculations of He and Li.