Shape of pion distribution amplitude

A scenario is investigated in which the leading-twist pion distribution amplitude phi(pi)(x) is approximated by the pion decay constant f(pi) for all essential values of the light-cone fraction x. A model for the light-front wave function Psi(x,k(perpendicular to)) is proposed that produces such a distribution amplitude and has a rapidly decreasing (exponential for definiteness) dependence on the light-front energy combination k(perpendicular to)(2)/x(1-x). It is shown that this model easily reproduces the fit of recent large-Q(2) BABAR data on the photon-pion transition form factor. Some aspects of the scenario with flat pion distribution amplitude are discussed.