The energy spectra of the hypernuclei He-5(Lambda) and O-17(Lambda) were studied within a multiphonon scheme, where the Lambda particle is coupled to particle-hole Tamm-Dancoff phonons describing the excitations of the core. A chiral interaction was used.
The calculations show that the core excitations push considerably, through their coupling, the Hartree-Fock energies down in energy and enrich the low-energy spectrum in O-17(Lambda)