A Note on Wandzura-Wilczek Relations

Abstract

Wandzura-Wilczek (WW) relations between matrix-elements of bilocal light-ray operators have recently regained interest in connection with off-forward scattering processes. Originally derived for matrix elements over leading-twist operators, their generalization to off-forward and exclusive processes gets complicated by the presence of higher-twist operators that are total derivatives of leading-twist ones and do not contribute to forward-scattering. We demonstrate that, for exclusive matrix-elements, the inclusion of these operators into WW-relations is essential for fulfilling constraints imposed by the conformal symmetry of massless QCD.

4 pages RevTex

References in corpus (2)

• Resummation of target mass corrections in two-photon processes: twist-two sector
• Wandzura-Wilczek-type relations of $\rho$-meson wave functions

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