Pion distribution amplitudes within the instanton model of QCD vacuum

The pion transition form factor for the process gamma*gamma* --> pi(0) at spacelike 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. (C) 2003 MAIK Nauka/Interperiodica.