0000000000025356
AUTHOR
N. I. Kochelev
Further Comments on a Vanishing Singlet Axial Vector Charge
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 $\eta'$-meson-quark coupling, which has been found to be compatible with the chiral quark model phenomenology.
Instantons and theΔI=1/2Rule
The instanton-induced interaction leads to a significant enhancement of the Ao weak amplitude determining the DeltaI = 1/2 rule, through the contribution of operators with dimension d = 9, as we show in the weak K--> pi(pi) decay.