Improved estimates of the pion-photon transition form factor in the (1 ≤ Q2≤ 5) GeV2range and their theoretical uncertainties

S. V. Mikhailov, A. V. Pimikov, N. G. Stefanis, Y. Foka, N. Brambilla, V. Kovalenko
2017 EPJ Web of Conferences  
We consider the pion-photon transition form factor at low to intermediate spacelike momenta within the theoretical framework of light-cone sum rules. We derive predictions which take into account all currently known contributions stemming from QCD perturbation theory up to the next-to-next-to-leading order (NNLO) and by including all twist terms up to order six. In order to enable a more detailed comparison with forthcoming high-precision data, we also estimate the main systematic theoretical
more » ... matic theoretical uncertainties, stemming from various sources, and discuss their influence on the calculations --- in particular the dominant one related to the still uncalculated part of the NNLO contribution. The analysis addresses, in broad terms, also the role of the twist-two pion distribution amplitude derived with different approaches.
doi:10.1051/epjconf/201713705016 fatcat:zobvt3dh7vhqvmwad6trmtbqwq