Pion-Photon Transition Form Factor: Living on the QCD Frontier

An analysis of all available data (CELLO, CLEO, BABAR) in the range [1 - 40] GeV2 for the pion-photon transition form factor in terms of light-cone sum rules with next-to-leading-order accuracy is discussed, including twist-four contributions and next-to-next-to-leading order and twist-six corrections-the latter two via uncertainties. The antithetic trend between the BABAR data for the γ*γπ0 and those for the γ*γη(η') transition is pointed out, emphasizing the underlying antagonistic mechanisms: endpoint enhancement for the first and endpoint-suppression for the second-each associated with pseudoscalar meson distribution amplitudes with distinct endpoint characteristics. (author)