Pion distribution amplitudes within the instanton model of QCD vacuum

Abstract

Pion transition form factor for the process $\gamma \ast \gamma \ast \to {\pi }^0$ at space-like values of photon momenta is calculated within the effective quark-meson model with the interaction induced by instanton exchange. The leading and next-to-leading order power asymptotics of the form factor and the relation between the light-cone pion distribution amplitudes of twists 2 and 4 and the dynamically generated quark mass are found.

Comments: 5 pages, 4 eps figures. Revised version: references and figures added