Inside our approach to the Model Spec

A method is formulated for the description of lambda hypernuclei in the framework of the unitary-model-operator approach (UMOA). The method is applied to $_Λ^{17}$O. A lambda-nucleon effective interaction is derived, taking the coupling of the sigma-nucleon channel into account. The lambda single-particle energies are calculated for the 0s_{1/2}, 0p_{3/2} and 0p_{1/2} states employing the Nijmegen soft-core (NSC), Jülich model-Ã (JÃ) and model-B (JB) hyperon-nucleon potentials.