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

S. S. Agaev

doi:10.1103/PhysRevD.72.114010 10.1103/PhysRevD.73.059902

paper

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

arXiv:hep-ph/0511192 · doi:10.1103/PhysRevD.72.114010 10.1103/PhysRevD.73.059902

Abstract

We reanalyze the $γ γ^{*} \to π^{0}$ transition form factor $F_{π γ} (Q^{2})$ 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 $F_{π γ} (Q^{2})$ . Obtained theoretical predictions are employed to deduce constraints on the pion DAs from CELLO and CLEO data.

15 pages, 7 figures. Numerical errors in $Φ_{4}^{(4)} (u)$ (Eq.(3.9)), and in $ϕ_{4}^{1} (u)$ , ρ_4^4(t,s), H_4^4(t)$ (Appendix) corrected. The figures and Section IV revised. Conclusions changed

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Higher twist distribution amplitudes of the pion and electromagnetic form factor $F_{π} (Q^{2})$

Impact of the higher twist effects on the γγ∗→π0 transition form factor

Abstract

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