ROLE OF THE AXIAL ANOMALY IN THE Z(0) MASS

The three-loop correction to the Z0 mass associated with the axial ano maly can, surprisingly, be evaluated in simple closed form if M(Z)2 mu ch-less-than m(t)2. While both top and bottom quarks are required to c ancel the divergence coming from the anomaly, the main contribution to DELTAM(Z) comes from the top quark and one has DELTAM(Z) = 1.4 [m(t)/ (150 GeV/c2)]2 MeV/C2.