The form factors for the photon to pseudoscalar meson transitions - an update

The form factors for the transitions pi-photon, eta-photon, eta’-photon and etac-photon are analyzed within the modified perturbative approach in which quark transverse degrees of freedom are retained. The results for the form factors are compared to experiment in detail. As compared to previous calculations within the same approach only little modifications of the meson distribution amplitudes are required in general in order to achieve agreement with experiment. Only for the pi-photon form factor a strong contribution from the second Gegenbauer term is found. It is also commented on the case of two virtual photons and on the transition form factors in the time-like region.