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arXiv · 1604.06391

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

S. V. Mikhailov·A. V. Pimikov·N. G. Stefanis
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Abstract

We consider the calculation of the pion-photon transition form factor $F^{\gamma^*\gamma\pi^0}(Q^2)$ 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 $F^{\gamma^*\gamma\pi^0}(Q^2)$ 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 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.

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S. V. Mikhailov, A. V. Pimikov, N. G. Stefanis. 2016-04-21. Systematic estimation of theoretical uncertainties in the calculation of the pion-photon transition form factor using light-cone sum rules. https://doi.org/10.1103/physrevd.93.114018

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