Impact of the higher twist effects on the $\gamma\gamma^{*} \to \pi^{0}$ transition form factor

Abstract

We reanalyze the $\gamma\gamma^{*} \to \pi^{0}$ transition form factor $F_{\pi\gamma}(Q^2)$ within the QCD light-cone sum rules method with the twist-4 accuracy. In computations the pion leading twist distribution amplitude (DA) with two nonasymptotic terms, and the renormalon method-inspired twist-4 DAs are used. The latters allow us to estimate impact of effects due to higher conformal spin components in the pion twist-4 DAs on the form factor $F_{\pi\gamma}(Q^2)$. Obtained theoretical predictions are employed to deduce constraints on the pion DAs from CELLO and CLEO data.