Parton distribution function for topological charge at one loop

Abstract

We present results for the $gg$-part of the one-loop corrections to the recently introduced "topological charge" GPD $\tilde{F}(x,q^2)$. In particular, we give expression for its evolution kernel. To enforce strict compliance with the gauge invariance requirements, we have used on-shell states for external gluons, and have obtained identical results both in Feynman and light-cone gauges. No "zero mode" $\delta (x)$ terms were found for the twist-4 gluon GPD $\tilde{F}(x,q^2)$.