Why are the isoscalar neutral current axial-vector couplings and isoscalar nucleon anomalous moments small?

Abstract

By using an argument based on the realization of chiral current algebras, we explain why the isoscalar neutral current axial-vector coupling and the isoscalar nucleon anomalous moments are small. We give an argument which predicts, ( G A N(0))p/( G A N(0)) n = ( H A N(0)) p/( H A N(0)) n = k p/ k n ≈ 1.79/−1.91, where k p and k n are the anomalous moments of the proton and neutron, respectively. ( G A N(0)) p and ( H A N(0)) p are the weak neutral current axial-vector coupling and the induced pseudoscalar coupling for the proton, respectively.