Wide-angle photoproduction of the $\eta'$-meson and its gluon content

TL;DR

This paper studies wide-angle photoproduction of the $ ext{η'}$ meson, highlighting the dominance of twist-2 contributions due to its gluon content, and proposes using this process to better understand the two-gluon distribution amplitude.

Contribution

It provides the first detailed prediction for $ ext{η'}$ photoproduction cross sections and helicity correlations considering twist-2 dominance, emphasizing the process's potential to probe gluonic structures.

Findings

$ ext{η'}$ photoproduction is dominated by twist-2 contributions.

Predictions for cross sections and helicity correlations are provided.

The process can improve understanding of the two-gluon distribution amplitude.

Abstract

We investigate wide-angle photoproduction of the $\eta'$ meson within the handbag approach to twist-3 accuracy. It turns out that, due to the gluon content of the $\eta'$, this process is dominated by twist-2 in contrast with pion and $\eta$ photoproduction. Using the presently available information on the twist-2 and twist-3 distribution amplitudes and on the $\eta - \eta'$ mixing, we provide prediction for the $\eta'$ cross section and helicity correlations. It is argued that $\eta'$ photoproduction is well suited to improve our knowledge of the two-gluon distribution amplitude.