Analysis of p-shell hypernuclei with ΛNN forces and the spin-state dependence of the ΛN effective interaction

From a chi2 fit to the Λ binding energy data of p-shell hypernuclei it has been identified that a zero-range three-body ΛNN force plays a crucial role in reducing the spin-state dependence of the central charge-independent two-body effective ΛN potential of Skyrme-type, gaussian, Yukawa and exponential shapes. The exchange contribution of the three-body ΛNN force to the interaction energy has been shown to play an important role. For a Skyrme-type ΛN potential found from the analysis of p-shell hypernuclei, a value of 28.52 MeV is obtained for Λ binding to infinite nuclear matter and also Λ binding in 5sub(Λ)He turns out to be in good agreement with experiment. But the other shapes with reasonable values of the range parameter fail to account for Λ binding to infinite nuclear matter and Bsub(Λ) of 5sub(Λ)He even qualitatively. The noncentral ΛN potentials (spin-orbit and tensor force) along with the low spin-state dependence of central two-body charge-independent ΛN potentials fail to account for the data even qualitatively. (author)