Tensor Coupling Effects on Spin Symmetry in the Anti-Lambda Spectrum of Hypernuclei

Effects of ΛΛ ω−tensor coupling on the spin symmetry of Λ spectra in Λ−nucleus systems are studied using relativistic mean-field theory. Taking ¹²C+Λ as an example, it is found that the tensor coupling enlarges the spin−orbit splittings of Λ by a factor of 5 but has a negligible effect on the wave functions of Λ. Similar conclusions are observed in other Λ−nuclei, including ¹⁶O+Λ, ⁴⁰Ca+Λ and ²⁰⁸Pb+Λ. It is indicated that the spin symmetry in anti-lambda-nucleus systems is still a good approximation irrespective of the tensor coupling.