Pion-Photon Transition Form Factor and Pion Distribution Amplitude in QCD: Facing the Enigmatic Behavior of the BaBar Data

Abstract

We present an extended analysis of the data for the pion-photon transition form factor from different experiments, CELLO, CLEO, and BaBar, and discuss various theoretical approaches which try to reason from them. We focus on the divergent behavior of the BaBar data for the pion and those for the $\eta ({\eta }^{\prime })$ pseudoscalar mesons and comment on recently proposed explanations for this discrepancy. We argue that it is not possible at present to accommodate these data within the standard QCD framework self-consistently.

5 pages, 2 figures, talk presented by the second author at the International Workshop on e^+e^- collisions from phi to psi (PHIPSI11), Novosibirsk (Russia), Sept. 19--22, 2011

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Cited by in corpus (5)

• Comparing antithetic trends of data for the pion-photon transition form factor
• Can we understand an auxetic pion-photon transition form factor within QCD? BaBar faces Belle
• The pion distribution amplitude and the pion-photon transition form factor in a nonlocal chiral quark model
• Study of pesudoscalar transition form factors within light front quark model
• $\eta$-$\gamma$ and ${\eta }^{\prime }$-$\gamma$ transition form factors in a nonlocal NJL model