Further Comments on a Vanishing Singlet Axial Vector Charge

Abstract

The recent suggestion of a vanishing flavor-singlet axial charge of nucleon due to a nontrivial vacuum structure is further amplified. A perturbative QCD discussion, applicable for the heavy quark contributions, relates it to the physics of the decoupling theorem. It is also shown that $g_A^0\simeq 0$ leads to a negative ${\eta }^{\prime }$-meson-quark coupling, which has been found to be compatible with the chiral quark model phenomenology.

Comments: 6 pages, Latex