Model independent constraints from vacuum and in-medium QCD Sum Rules

Abstract

We discuss QCD sum rule constraints based on moments of vector meson spectral distributions in the vacuum and in a nuclear medium. Sum rules for the two lowest moments of these spectral distributions do not suffer from uncertainties related to QCD condensates of dimension higher than four. We exemplify these relations for the case of the omega meson and discuss the issue of in-medium mass shifts from this viewpoint.Comment: 6 pages, 2 figures, to appear in Eur. Phys. J.