Pseudoscalars in the instanton liquid model

The masses and decay constants of the nonet of pseudoscalar mesons are investigated in the instanton liquid model of the QCD vacuum using the long wavelength approximation. The instanton liquid induced interactions between the light quarks yield conservation laws for the flavor currents that are consistent with QCD including anomalies. We show that the induced anomaly in the flavor singlet current gives rise to an η′ mass that is in agreement with the Witten-Veneziano relation. The η-η′ mixing matrix coincides with the result derived previously by Veneziano.