Pion transition form factor at the two-loop level vis-\`a-vis experimental data

Understand

We use light-cone QCD sum rules to calculate the pion-photon transition form factor, taking into account radiative corrections up to the next-to-next-to-leading order of perturbation theory.

• We compare the obtained predictions with all available experimental data from the CELLO, CLEO, and the BaBar Collaborations.
• We point out that the BaBar data are incompatible with the convolution scheme of QCD, on which our predictions are based, and can possibly be explained only with a violation of the factorization theorem.
• We pull together recent theoretical results and comment on their significance.