Hadronic Spectral Functions in Nuclear Matter

Abstract

We study the in-medium properties of mesons $(\ddot{I}€,\hat{I}\cdot ,\ddot{I})$ 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 $\hat{I}”$ dynamics in nuclear matter. We find a strong interplay of the $\ddot{I}$ meson and the $D_{13}(1520)$, which moves spectral strength of the $\ddot{I}$ spectrum to smaller invariant masses and leads to a broadening of the baryon resonance. The optical potential for the $\hat{I}\cdot$ 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.

71 pages, 31 figures, accepted for Publication in Nuclear Physics A; minor modifications of the manuscript, several typos corrected