Theoretical description and measurement of the pion-photon transition form factor

Detailed predictions for the scaled pion-photon transition form factor are given, derived with the method of light-cone sum rules and using pion distribution amplitudes with two and three Gegenbauer coefficients obtained from QCD sum rules with nonlocal condensates. These predictions agree well with all experimental data that are compatible with QCD scaling (and collinear factorization), but disagree with the high-$Q^2$ data of the BaBar Collaboration that grow with the momentum. A good agreement of our predictions with results obtained from AdS/QCD models and Dyson-Schwinger computations is found.
Comment: 10 pages, 4 figures, 6 references added, minor style corrections, Presented by the first author at the Light-Cone Conference 2013, May 20-24, 2013, Skiathos, Greece