Violation of the Bjorken Sum Rule in QCD

Stefano Forte

Published 1992-11-07, updated 1992-11-17Version 2

We show that the Bjorken sum rule for the first moment of the polarized nucleon structure function $g_1$ is not necessarily satisfied in QCD if the axial anomaly is taken into account. We argue that nonperturbative QCD effects should lead to a violation of the sum rule of the order of the percentage isospin violation in current quark masses.