Nonlocal chiral anomaly and generalized parton distributions

TL;DR

This paper explores the nonlocal chiral anomaly in QCD, revealing its relations with generalized parton distributions (GPDs) and their role in mass generation of the η' meson, connecting anomalies to observable GPD features.

Contribution

It introduces a nonlocal generalization of the QCD chiral anomaly along the light-cone and links it to GPDs and the anomaly pole, enhancing understanding of anomaly effects in hadron structure.

Findings

Derived relations between twist-two, twist-three, and twist-four GPDs mediated by the anomaly.

Connected the anomaly pole in GPD $ ilde{E}$ to perturbative Compton scattering calculations.

Showed the cancellation of the anomaly pole at the GPD level, clarifying its physical implications.

Abstract

We discuss the nonlocal generalization of the QCD chiral anomaly along the light-cone and derive relations between twist-two, twist-three and twist-four generalized parton distributions (GPDs) mediated by the anomaly. We further establish the connection to the `anomaly pole' in the GPD $\tilde{E}$ recently identified in the perturbative calculation of the Compton scattering amplitudes, and demonstrate its cancellation at the GPD level. Our work helps elucidate the previously unexplored connection between GPDs, the chiral anomaly, and the mass generation of the $\eta'$ meson.