Quark-Hadron Duality, Axial Anomaly and Mixing

Interplay between axial anomaly and quark-hadron duality in the presence of strong mixing is considered. The anomaly sum rule for meson transition form factors based on the dispersive representation of axial anomaly and quark-hadron duality in octet channel is analyzed. The comparison of this sum rule to the experimental data on the transition form factors of the eta and eta' mesons shows that the interval of duality in this channel is rather small, contradicting the usual understanding of quark-hadron duality. The same values of interval of duality are supported by considering the two-point correlator in the local duality limit. This contradiction may be resolved by introducing of some nonperturbative non-one-pion exchange correction to the relevant spectral density. The form and value of this correction are discussed. DOI: 10.1134/S0021364011220061