  We investigate single-particle properties in infinite nuclear matter using a
variety of interactions. One of the focal points is to study the impact of
chiral three-nucleon forces on the nucleon self-energy and related quantities,
such as spectral function and momentum distribution. We also present results
for pairing correlations in nuclear matter. We find characteristic and
systematic differences between the predictions obtained with the (softer)
chiral interactions and those based on one-boson-exchange or phenomenology.
