Off-shell ρ-ω mixing in QCD sum rules

Abstract

The ${\mathit{q}}^2$ dependence of the ρ-ω mixing amplitude is analyzed with the use of QCD sum rules and dispersion relations. Going off shell the mixing decreases, changes sign at ${\mathit{q}}^2$≃0.4${\mathit{m}}_{\mathrm{\rho }}^2$>0, and is negative in the spacelike region. Implications of this result for the isospin breaking part of the nuclear force are discussed.