Λ hypernuclei: Overview and single-particle nature

A brief overview of S=−1 hypernuclei is presented, followed for the main course by a careful, judicious construction of a density-dependent nonlocal Λ-nucleus potential due to Millener, Dover and Gal. The recent Λ level-spectra information obtained from the (π⁺, K⁺) experiment at Brookhaven has been combined with that earlier derived from (K⁻, π⁻) reactions in order to determine three parameters which are needed to give a good account of the data and which turn out rather tightly constrained. The analysis yields D_Λ=(28.0±0.5) MeV for the Λ-nuclear well depth and m*/m=0.78±0.02 for the ratio of Λ effective mass to its free mass. No explicit quark signature, e.g., s-quark partial deconfinement, is found to be necessitated by fitting to these data.