A search for anomalous contribution in e(+)e(-)->pi(0)/eta gamma annihilations

Data on e(+)e(-) --> eta/pi(0) collected by the Neutral Detector at Novosibirsk in a c.m. energy range up to 1.04 GeV have been studied with a purpose to single out of the scattering amplitude the triangle anomaly contribution predicted by QCD, PCAC and Chiral Theories. We show that the cross section for e(+)e(-) --> pi(0) gamma exhibits no sensitivity to the pi(0) triangle anomaly; instead, the cross section for e(+)e(-) --> eta gamma shows a clear sensitivity to the value of the eta triangle anomaly and the best fit corresponds to a value for the eta width in good correspondence with the world average value. It is also shown that the value of the rho --> eta gamma branching fraction is noticeably influenced by the existence of the anomaly. Finally, we give for the first time the absolute value for the hadronic phases of the vector mesons for the decay modes eta gamma and pi(0) gamma.