Anomalies, symmetries and strangeness content of the proton

Abstract

The matrix elements of the operators of strange quark fields s¯Γ s where Γ is 1 or γ μ γ ⁵ between a proton state is calculated. The sigma term is found to be ≈ 41 MeV and the SU(3) singlet axial matrix element is found to be ≈ 0.22, both in agreement with experiment. The sigma term is found using the trace anomaly, while the determination of the axial vector current matrix element is from QCD sum rules. These correspond to (ie.943-1) ≈ 0.12 and for the axial current Δ s ≈ -0.12, respectively. The role of the anomalies in maintaining flavor symmetry in the presence of substantial differences in quark masses is pointed out. This suggests that there is no need to invoke an intrinsic strange quark component in the proton wave function.