The spectral function of the ω meson in nuclear matter from a coupled-channel resonance model

We calculate the spectral function of the ω meson in nuclear matter at zero temperature by means of the low-density theorem. The ωN forward scattering amplitude is calculated within a unitary coupled-channel effective Lagrangian model that has been applied successfully to the combined analysis of pion- and photon-induced reactions. While the peak of the ω spectral distribution is shifted only slightly, we find a considerable broadening of the ω meson due to resonance-hole excitations. For ω mesons at rest with respect to the surrounding nuclear medium, we find an additional width of about 60 MeV at saturation density.