rho-omega mixing in asymmetric nuclear matter via a QCD sum rule approach - art. no. 015204

We evaluate the operator product expansion (OPE) for a mixed correlator of the isovector and isoscalar vector currents in the background of the nucleo n density with intrinsic isospin asymmetry (i.e., excess of neutrons over p rotons) and match it with its imaginary part, given by resonances and conti nuum, via the dispersion relation. The leading density-dependent contributi on to rho-omega mixing is due to the scattering term, which turns out to be larger than any density dependent piece in the OPE. We estimate that the a symmetric density of n(n)-n(p) similar to2.5 x 10(-2) fm(-3) induces the am plitude of rho-omega mixing, equal in magnitude to the mixing amplitude in vacuum, with the constructive interference for positive and destructive for negative values of n(n)-n(p). We revisit sum rules for vector meson masses at finite nucleon density to point out the numerical importance of the scr eening term in the isoscalar channel, which turns out to be one order of ma gnitude larger than any density-dependent condensates over the Borel window . This changes the conclusions about the density dependence of m(omega), in dicating similar to 40 MeV increase at nuclear saturation density.