σ and ω meson propagation in a dense nuclear medium

The propagation of the scalar (σ) and vector (ω) mesons in nuclear matter is studied in detail using the Walecka model over a wide range of densities and including the effects of a finite σ width through the inclusion of a two-pion loop. We calculate the dispersion relation and spectral functions of the σ and (transverse and longitudinal) ω mesons, including the effect of σ-ω mixing in matter. It is shown that the mixing effect is quite important in the propagation of the (longitudinal) ω and σ mesons above normal nuclear matter density. We find that there is a two-peak structure in the spectral function of the σ channel, caused by σ-ω mixing.