https://doi.org/10.1051/epjconf/201713705016
Improved estimates of the pion-photon transition form factor in the (1 ≤ Q2 ≤ 5) GeV2 range and their theoretical uncertainties
1 Bogoliubov Laboratory of Theoretical Physics, JINR, 141980 Dubna, Russia
2 Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000, P. R. China
3 Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum, Germany
a e-mail: mikhs@theor.jinr.ru
b e-mail: pimikov@mail.ru
c e-mail: stefanis@tp2.ruhr-uni-bochum.de
Published online: 22 March 2017
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 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.
© The Authors, published by EDP Sciences, 2017
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
