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arXiv · 2609.20545

Computability of GPDs near $x=\pmξ$ in Lattice QCD

Yushan Su·Xiangdong Ji·Yizhuang Liu·Rui Zhang
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Abstract

In lattice QCD computations of generalized parton distributions (GPDs), the large momentum expansion generally requires all hard scales, $2|x\pmξ|P^z$ and $2|1\pm x|P^z$, to be much larger than $Λ_{\rm QCD}$. We show that this condition can be relaxed for $2|x\pmξ|P^z$ at large $ξ$, making the important $x\sim\pmξ$ regions accessible to lattice calculations and considerably expanding the region of computability. Revisiting previous lattice results with complete one-loop matching, we obtain the expected partonic threshold behavior---GPDs continuous at $x=\pmξ$ but with discontinuous derivatives---which has not previously been observed on the lattice. We thus obtain, for the first time, important prediction for GPDs in the distribution-amplitude-like region, which smoothly connects the quark and antiquark PDF-like behaviors.

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Yushan Su, Xiangdong Ji, Yizhuang Liu, Rui Zhang. 2026-09-17. Computability of GPDs near $x=\pmξ$ in Lattice QCD. https://arxiv.org/abs/2609.20545

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