A density-dependent relativistic Hartree approach for hypernuclei

Λ, Σ, and Ξ (multi-)hypernuclei are investigated within a density-dependent relativistic Hartree approach. To this end, the covariant field theory recently developed by Lenske and Fuchs is extended to hypernuclear systems, leading to rearrangement self-energies in the baryonic field equations. Self-consistent solutions, including ω-hyperon tensor couplings, are obtained in the Hartree limit with the σ- and ω-nucleon couplings adjusted to Dirac-Brueckner-Hartree-Fock results for infinite nuclear matter, utilizing a local density approximation. With the meson-nucleon couplings compatible with realistic nucleon-nucleon potentials, the description remains free of adjustable parameters on the nucleonic side, while meson-hyperon couplings are fixed by SU(6) symmetry or fitted to available experimental data. In addition, results for Λ hypernuclei are presented within a purely phenomenological relativistic mean-field model including σ and ω self-interactions. Special attention is devoted to the impact of the ρ-meson field in Σ and Ξ hypernuclei. Finally, the 'hyperon-halo' of multi-hypernuclei and the way it is affected by rearrangement effects is studied. (author)