Systematic estimation of theoretical uncertainties in the calculation of the pion-photon transition form factor using light-cone sum rules

We consider the calculation of the pion-photon transition form factor ${F}^{{\ensuremath{\gamma}}^{*}\ensuremath{\gamma}{\ensuremath{\pi}}^{0}}({Q}^{2})$ within light-cone sum rules focusing attention to the low-mid region of momenta. The central aim is to estimate the theoretical uncertainties which originate from a wide variety of sources related to (i) the relevance of next-to-next-to-leading order radiative corrections (ii) the influence of the twist-four and the twist-six term (iii) the sensitivity of the results on auxiliary parameters, like the Borel scale ${M}^{2}$, (iv) the role of the phenomenological description of resonances, and (v) the significance of a small but finite virtuality of the quasireal photon. Predictions for ${F}^{{\ensuremath{\gamma}}^{*}\ensuremath{\gamma}{\ensuremath{\pi}}^{0}}({Q}^{2})$ are presented which include all these uncertainties and found to comply within the margin of experimental error with the existing data in the ${Q}^{2}$ range between 1 and $5\text{ }\text{ }{\mathrm{GeV}}^{2}$, thus justifying the reliability of the applied calculational scheme. This provides a solid basis for confronting theoretical predictions with forthcoming data bearing small statistical errors.