Pion-distribution amplitude within the instanton model

The leading-twist pion-distribution amplitude is obtained at a low normaliz ation scale of order rho (c) (inverse average size of an instanton). Pion d ynamics, consistent with gauge invariance and low-energy theorems, is consi dered within the instanton vacuum model. The results are QCD-evolved to hig her momentum-transfer values and are in agreement with recent data from CLE O on the pion transition form factor. It is also shown that some previous c alculations violate the axial Ward-Takahashi identity. (C) 2001 MAIK "Nauka /Interperiodica".