A new effective Lagrangian for nuclear matter

The relativistic mean field model, the Zim\'anyi - Moszkowski (ZM) Lagrangian describes nuclear matter and stable finite nuclei even in the non-relativistic limit. It fails, however, to predict the correct non-relativistic spin-orbit (SO) coupling. In this paper we improve on this matter by an additional tensor coupling analogous to the anomalous gyromagnetic ratio. It can be adjusted to describe the SO-term without changing the mean field solution of the ZM-Lagrangian for nuclear matter.