Hadronic Spectral Functions in Nuclear Matter

Abstract

We study the in-medium properties of mesons $(π,η,ρ)$ and baryon resonances in cold nuclear matter within a coupled-channel analysis. The meson self energies are generated by particle-hole excitations. Thus multi-peak spectra are obtained for the mesonic spectral functions. In turn this leads to medium-modifications of the baryon resonances. Special care is taken to respect the analyticity of the spectral functions and to take into account effects from short-range correlations both for positive and negative parity states. Our model produces sensible results for pion and $Δ$ dynamics in nuclear matter. We find a strong interplay of the $ρ$ meson and the $D_{13}(1520)$, which moves spectral strength of the $ρ$ spectrum to smaller invariant masses and leads to a broadening of the baryon resonance. The optical potential for the $η$ meson resulting from our model is rather attractive whereas the in-medium properties modifications of the $S_{11}(1535)$ are found to be quite small.