Meson-current correlation functions in instanton vacuum

The correlation functions (polarization operators) of colorless currents are calculated over the entire range of (Euclidean) momenta in the instanton vacuum of quantum chromodynamics. The appearance of a pion pole due to the spontaneous breaking of chiral invariance is studied explicitly. The mass and the axial constant of the ..pi.. meson, f/sub ..pi../, are calculated in terms of the parameters found previously for the instanton medium.