Nonlocal chiral contributions to generalized parton distributions of the proton at nonzero skewness

TL;DR

This paper calculates one-loop meson contributions to the proton's generalized parton distributions at nonzero skewness using a nonlocal covariant chiral effective theory, ensuring polynomiality and analyzing form factor effects.

Contribution

It introduces a nonlocal covariant chiral framework to compute GPDs with meson loops at nonzero skewness, incorporating a consistent relativistic regulator.

Findings

Nonzero skewness GPDs derived from meson loops satisfy polynomiality.

Meson loops significantly affect the proton's Dirac, Pauli, and gravitational form factors.

The framework provides a consistent method to include meson contributions in GPD calculations.

Abstract

We compute the one-loop contributions to spin-averaged generalized parton distributions (GPDs) in the proton from pseudoscalar mesons with intermediate octet and decuplet baryon states at nonzero skewness. Our framework is based on nonlocal covariant chiral effective theory, with ultraviolet divergences regularized by introducing a relativistic regulator derived consistently from the nonlocal Lagrangian. Using the splitting functions calculated from the nonlocal Lagrangian, we find the nonzero skewness GPDs from meson loops by convoluting with the phenomenological pion GPD and the generalized distribution amplitude, and verify that these satisfy the correct polynomiality properties. We also compute the lowest two moments of GPDs to quantify the meson loop effects on the Dirac, Pauli and gravitational form factors of the proton.