On the structure of Σ-hypernuclei

We investigate theΣ-nucleus potential in the framework of a relativistic mean field approximation. As input for the elementaryΣN interaction we supplement theω-repulsion by the exchange of an effective, complexσ-meson to account for theΣN → ΛN conversion. As the main result we find that the strength of ths absorptive central potential is smaller than the corresponding real part, whereas in the spin-orbit interaction, which is expected to be much weaker than for a nucleon, the imaginary component dominates.