6 v 4 2 9 Se p 20 04 ρ − ω splitting and mixing in nuclear matter

We investigate the splitting and mixing of ρ and ω mesons in nuclear matter. The calculations were performed on the basis of QCD sum rules and include all operators up to mass dimension-6 twist-4 and up to first order in the coupling constants. Special attention is devoted to the impact of the scalar 4-quark condensates on both effects. In nuclear matter the Landau damping governs the ρ− ω mass splitting while the scalar 4-quark condensates govern the strenght of individual mass shifts. A strong in-medium mass splitting causes the disappearance of the ρ− ω mixing.