PHOTON-MESON TRANSITION FORM-FACTORS GAMMA-PI(0), GAMMA-ETA, AND GAMMA-ETA' AT LOW AND MODERATELY HIGH Q(2)

We study photon-meson transition form factors gamma(Q(2))gamma --> pi (0),eta,eta(t) at low and moderately high Q(2) assuming a nontrivial h adronlike <q(q)over bar> structure of the photon in the soft region. I n the hard region, the <q(q)over bar> photon wave function contains bo th a perturbative tail of the soft wave function such as the wave func tion of an ordinary hadron and a standard QED pointlike <q(q)over bar> component. The latter provides the 1/Q(2) asymptotical behavior of th e transition form factor in accordance with QCD. The data on the gamma pi(0) form Factor are used for fixing the soft photon wave function w hich is found to have the same structure as the soft wave function of the pion reconstructed from the elastic pion form factor. Assuming uni versality of the ground-state pseudoscalar meson wave functions we cal culate the gamma eta, gamma eta' transition form factors and eta --> g amma gamma, eta' --> gamma gamma partial widths and found them to be i n perfect agreement with the data.