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 leads to a negative η′-meson-quark coupling, which has been found to be compatible with the chiral quark model phenomenology.
Cheng, Ta-Pei Kochelev, Nikolai Vento Torres, Vicente 1999 Further comments on a vanishing singlet axial vector charge Modern Physics Letters A 14 3 205 209
