Subleading power corrections to the pion-photon transition form factor in QCD

• Published in: The journal of high energy physics Vol. 2017; no. 12; pp. 1 - 38
• Main Authors: Wang, Yu-Ming, Shen, Yue-Long
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2017; Springer Nature B.V; SpringerOpen
• Subjects: Classical and Quantum Gravitation; Elementary Particles; Factorization; High energy physics; Perturbative QCD; Physics; Physics and Astronomy; Quantum chromodynamics; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Theoretical Physics; Regularization; Relativity Theory; Resummation; String Theory; Sum rules; Resummation; Perturbative QCD
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP12(2017)037

A bstract We reconsider QCD factorization for the leading power contribution to the γ * γ → π 0 form factor F γ * γ → π 0( Q 2 ) at one loop using the evanescent operator approach, and demonstrate the equivalence of the resulting factorization formulae derived with distinct prescriptions of γ 5 in dimensional regularization. Applying the light-cone QCD sum rules (LCSRs) with photon distribution amplitudes (DAs) we further compute the subleading power contribution to the pion-photon form factor induced by the “hadronic” component of the real photon at the next-to-leading-order in O α s , with both naive dimensional regularization and ’t Hooft-Veltman schemes of γ 5 . Confronting our theoretical predictions of F γ * γ →π0 ( Q 2 ) with the experimental measurements from the BaBar and the Belle Collaborations implies that a reasonable agreement can be achieved without introducing an “exotic” end-point behaviour for the twist-2 pion DA.