Instantons and spin physics Available to Purchase

It is shown that a consistent treatment of the axial anomaly leads to an explicit cancellation between the the infrared and ultraviolet contributions to the flavor singlet axial charge. This result is a consequence of the simultaneous crossing of the zero point energy and the ultraviolet cut-off by quark levels of defined chirality from the vacuum in the presence of gluon fields. Based on this consideration we give the arguments in favor of a large violation of the Ellis-Jaffe sum rule by predicting the vanishing of the flavor singlet axial charge $gA0$ in a plausible scenario. From this result the value of the gluon polarization is estimated by using the Kühn-Zakharov value for the matrix element of the axial anomaly.