Axial baryonic charge and the spin content of the nucleon: A lattice investigation

Abstract

The axial baryonic charge of the nucleon, $\Delta \Sigma$, which measures the quark fraction of the nucleon spin, is computed in lattice QCD with dynamical staggered fermions. We obtain the value $\Delta \Sigma =0.18\mathrm{}\pm 0.02$. This suggests that the quark spin is responsible for very little of the nucleon spin.