Chiral symmetry and medium modifications of mesons

Using QCD sum rules we investigate the in-medium behavior of pseudo-scalar and vector mesons. The rho meson is considered within a scenario of pure chiral restoration by dropping the chirally odd condensates. The interplay of mass shift and broadening of the spectral function is highlighted. We apply finite density QCD sum rules to mesons consisting of a heavy and a light quark (D, Ds and B) and investigate their sensitivity to the chiral condensate and consider the splitting of particle and antiparticle spectral functions with increasing density of the ambient nuclear matter. In order to gain a more direct dependence on the chiral condensate and other potential order parameters of chiral symmetry we present a series of Weinberg-Shuryak type sum rules for heavy-light systems at finite densities. Furthermore, the special role of the gluon condensates for systems consisting of two heavy quarks (e.g. J/Psi) and the QCD trace anomalie allows an extension of the method to large temperatures at non-zero baryon densities using the Rossendorf quasi-particle model.