Modeling B19 as a B17−n−n three-body system in the unitary limit

We present a model description of the bound $^{19}\mathrm{B}$ isotope in terms of a $^{17}\mathrm{B}\ensuremath{-}n\ensuremath{-}n$ three-body system where the two-body subsystems $^{17}\mathrm{B}\ensuremath{-}n$ and $n\ensuremath{-}n$ are unbound (virtual) states close to the unitary limit. The $^{19}\mathrm{B}$ ground state is well described in terms of two-body potentials only, and two low-lying resonances are predicted. Their eventual link with the Efimov physics is discussed. This model can be naturally used to describe the recently discovered resonant states in $^{20,21}\mathrm{B}$.