THE QCD TRIANGULAR AXIAL ANOMALY AND THE CALCULATION OF MASS OF THE ETA' MESON AND ETA-]3-PI DECAY

It is shown that the physical effects arising from the global QCD anomaly in the divergence of the flavor-singlet axial vector current are essential to yield the correct phenomenological features of pi --> 3 pi decay and good agreement for the eta' meson mass. These results confirm the usefulness of the instanton-induced global QCD anomaly on a par with the global QED anomaly in pi(0) --> 2 gamma decay.