The Continuum Spectrum of Hypernuclear Trios

Abstract

The spectrum of hypernuclear trios composed of a $Λ$ baryon and two nucleons is the subject of an ongoing experimental campaign, aiming to study the interaction of the $Λ$ particle with a neutron, and the 3-body $Λ$-nucleon-nucleon force. In this manuscript we utilize baryonic effective field theory at leading order, constrained to reproduce the available low energy light hypernuclear data, to study the continuum spectrum of such hypernuclear trios. Using the complex scaling method and the inverse analytic continuation in the coupling constant method we find the existence of a virtual state in the $Λn p$ $J^π=\frac{3}{2}^{+}$ channel, leading to cross-section enhancement near threshold. For the $Λn n$ $J^π=\frac{1}{2}^{+}$ channel we predict a resonance state. Depending, however, on the value of the $ΛN$ scattering length, the resonance pole moves from the physical to the unphysical complex energy sheet within the experimental bounds.