Effects of $\Lambda$ hyperons on the nuclear equation of state in a Dirac-Brueckner-Hartree-Fock model

We predict the energy per baryon in nuclear matter with non-zero fraction of $\Lambda$ hyperons. We include Dirac effects on the nucleons as well as the $\Lambda$ and describe how the latter is implemented. We use the nucleon-hyperon meson-exchange potentials from the Juelich group, the latest as well as an earlier version. The dependence of the results on the many-body framework and on the nucleon-hyperon interaction model is discussed.