Axial and tensor charge of the nucleon in the Dirac orbital model

Abstract

Using the expansion of the baryon wave function in a series of products of single quark bispinors (Dirac orbitals), the nonsinglet axial and tensor charge of the nucleon are calculated. The leading term yields ${G_A}/{G_V} = 1.27$ and in good agreement with experiment. Calculation is essentially parameter-free and depends on the string tension $\sigma$ and $\alpha_s$, fixed at standard values. The importance of lower Dirac bispinor component, yielding 18% to the wave function normalization is stressed.