  Symmetric nuclear matter is studied in the self-consistent, in-medium
$T$-matrix approach. One-body spectral function, optical potential, and
scattering width are calculated. Properties of quasi-particle excitations at
the Fermi surface are discussed. Dispersive self-energies are dominated by
contributions from the $^1S_0$, $3S_1-^3D_1$, and $^3P_1$ partial waves.
