Constraints on distribution amplitudes of the η and η' mesons in the light of new experimental results

Constraints on the distribution amplitudes of the SU (f) (3) singlet eta (1) and octet eta (8) states are obtained from a comparison of the theoretical predictions for the eta gamma and eta'gamma electromagnetic transition form factors with experimental data of the CLEO and BaBar Collaborations. In calculations of the form factors F (eta(eta')gamma) (Q (2)) the power-suppressed corrections arising from the end-point integration regions x -> 0,1 are taken into account by employing the infrared renormalon approach. It is demonstrated that the power-suppressed corrections allow one to describe the data on the eta gamma and eta'gamma transitions within a framework of the SU (f) (3) octet-singlet basis using one mixing angle for both the physical states and decay constants.