Delocalization of the axial charge in the chiral limit

The nucleonʹs axial vector charge, gA, becomes delocalized in the chiral limit. When mπ=0, and SU(2)L×SU(2)R is exact, 1/3 of the nucleonʹs axial charge is to be found at infinite distance from the nucleon. For finite mπ this result is approached smoothly as mπ→0. We illustrate this effect by considering the lepton–proton spin–spin interaction arising from Z0 exchange as a function of mπ. Delocalization may have implications for lattice calculations of gA and in nuclei.