ΛN Spin-Orbit Splittings in _Λ⁹Be and _Λ¹³C Studied with One-Boson-Exchange ΛN Interactions

Movitated by the on-going γ-ray experiments at the Alternating Gradient Synchrotron at Brookhaven National Laboratory, we discuss the energy splittings of the 5/2₁⁺-3/2₁⁺ doublet in _Λ⁹Be and the 3/2₁^--1/2₁^- doublet in _Λ¹³C for which the ΛN spin-orbit ( LS) and antisymmetric spin-orbit ( ALS) forces are relevant. In the microscopic 2α+Λ ( 3α+Λ) model for _Λ⁹Be ( _Λ¹³C), all the available Nijmegen one-boson-exchange (OBE) model ΛN interactions lead to a wide range of splittings of 0.08–0.20MeV in _Λ⁹Be and 0.39–0.96MeV in _Λ¹³C. On the other hand, if we use information from quark-model ΛN interactions which have generally large ALS force, the splittings become about half of the smallest OBE model prediction.