Nucleon magnetic moments beyond the perturbative chiral regime

Abstract

The quark mass dependence of nucleon magnetic moments is explored over a wide range. Quark masses currently accessible to lattice QCD, which lie beyond the regime of chiral perturbation theory (χPT), are accessed via the cloudy bag model (CBM). The latter reproduces the leading nonanalytic behavior of χPT, while modeling the internal structure of the hadron under investigation. We find that the predictions of the CBM are succinctly described by the simple formula μN(mπ)=μN(0)/(1+αmπ+βmπ2), which reproduces the lattice data, as well as the leading nonanalytic behavior of χPT. As this form also incorporates the anticipated Dirac moment behavior in the limit mπ→∞, it constitutes a powerful method for extrapolating lattice results to the physical mass regime.