Tensor coupling effects on spin symmetry in the anti-lambda spectrum of hypernuclei

Effects of Λω-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.