Flavor symmetry breaking in quark magnetic moments

Abstract

We discuss the magnetic moments of the baryons allowing for flavor symmetry breaking in the quark magnetic moments. We show that there is a correlation between isospin symmetry breaking and data for the nucleon spin structure obtained from deep inelastic scattering. For small values of the isospin symmetry breaking, of the order of $5\%$, the magnetic moments and weak axial-vector form factors alone indicate a value of the spin polarization $ΔΣ\leq 0.20$. Larger values of the spin polarization are compatible only with large isospin symmetry breaking. We also calculate weak axial-vector form factors, which are independent of the symmetry breakings, from magnetic moment data and find good agreement with experiment.