https://doi.org/10.1051/epjconf/201922203017
Form factor π0γ*γ in lightcone sum rules combined with renormalization-group summation vs experimental data.
1
Department of Physics, Universidad Técnica Federico Santa María,
Casilla 110-V,
Valparaíso,
Chile
2
Bogoliubov Laboratory of Theoretical Physics, JINR,
141980
Dubna,
Russia
3
Institute of Modern Physics, Chinese Academy of Science,
Lanzhou
730000,
China
4
Ruhr-Universität Bochum, Fakultät für Physik and Astronomie, Institut für Theoretische Physik II,
D-44780
Bochum,
Germany
* e-mail: cesar.ayala@usm.cl
** e-mail: mikhs@theor.jinr.ru
*** e-mail: pimikov@mail.ru
**** e-mail: stefanis@tp2.ruhr-uni-bochum.de
Published online: 19 November 2019
We consider the lightcone sum-rule (LCSR) description of the pionphoton transition form factor in combination with the renormalization group of QCD. The emerging scheme represents a certain version of Fractional Analytic Perturbation Theory and significantly extends the applicability domain of perturbation theory towards lower momenta Q2 ≲ 1 GeV2. We show that the predictions calculated herewith agree very well with the released preliminary data of the BESIII experiment, which have very small errors just in this region, while the agreement with other data at higher Q2 is compatible with the LCSR predictions obtained recently by one of us using fixed-order perturbation theory.
© The Authors, published by EDP Sciences, 2019
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.
