  Brueckner theory is used to investigate the properties of hyperons in nuclear
matter. The hyperon-nucleon interaction is taken from chiral effective field
theory at next-to-leading order with SU(3) symmetric low-energy constants.
Furthermore, the underlying nucleon-nucleon interaction is also derived within
chiral effective field theory. We present the single-particle potentials of
Lambda and Sigma hyperons in symmetric and asymmetric nuclear matter computed
with the continuous choice for intermediate spectra. The results are in good
agreement with the empirical information. In particular, our calculation gives
a repulsive Sigma-nuclear potential and a weak Lambda-nuclear spin-orbit force.
