Vector-meson–baryon coupling constants in QCD sum rules

The external-field quantum chromodynamics (QCD) sum rules method is used to evaluate the coupling constants of the vector mesons {ρ} and {ω} to the nucleon and the Λ,Σ, and {Ξ} baryons. It is shown that these coupling constants as calculated from QCD sum rules are consistent with SU(3)-flavor relations. By assuming ideal mixing, this leads to a determination of the $F/(F+D)$ ratio of the vector-meson octet: we find αᵥ=1 and αₘ=0.18 for the vector and the magnetic $F/(F+D)$ ratios, respectively. The sensitivity of the results to the unknown vacuum susceptibility {ζ} is discussed. The coupling constants with SU(3)-breaking effects taken into account are also calculated.