On chiral corrections to nucleon GPD

TL;DR

This paper derives the leading chiral correction to the nucleon GPD at zero skewness using pion-nucleon chiral perturbation theory, addressing nonlocal operator challenges and clarifying GPD mixing effects.

Contribution

It introduces a method to directly compute chiral corrections for nonlocal operators, resolving ambiguities in inverse Mellin transformations for nucleon GPDs.

Findings

Chiral correction to nucleon GPD at ξ=0 derived

Mixing between axial and vector GPDs is suppressed by m_π^2/M_N^2

Method addresses nonlocal operator challenges in chiral perturbation theory

Abstract

Within the pion-nucleon chiral perturbation theory we derive the leading chiral correction to the nucleon GPD at $\xi=0$. We discuss the difficulties of consideration of nonlocal light-cone operators within the theory with a heavy particle and the methods to solve the difficulties. The consideration of the chiral corrections directly for nonlocal operators allows to resolve the ambiguity of the inverse Mellin transformation. In particular, we show that the mixing between axial and vector GPDs are of order $m_\pi^2/M_N^2$, which is two orders of magnitude less that it follows from the Mellin moments calculation.