QCD equalities for baryon current matrix elements

Abstract

An examination of the symmetries manifest in the QCD path integral for current matrix elements reveals various equalities among the quark sector contributions. QCD equalities among octet baryon magnetic moments lead to a determination of the disconnected sea-quark contribution to nucleon magnetic moments, which is the most reliable determination in the literature. Matching QCD equalities to recent calculations of decuplet baryon magnetic moments in chiral perturbation theory (χPT) reveals an equivalence between χPT to O(${\mathit{p}}^2$) and the simple quark model with an explicit disconnected sea-quark contribution. New insights into SU(3)-flavor symmetry breaking, sea contributions, and constituent quark composition are obtained. The strangeness contribution to nucleon magnetic moments is found to be large at ${\mathit{G}}_{\mathit{M}}^{\mathit{s}}$(0)=-0.75±0.30${\mathrm{\mu }}_{\mathit{N}}$. The QCD equalities must be followed by any model which hopes to capture the essence of nonperturbative QCD. Not all models are in accord with these symmetries. © 1996 The American Physical Society.