Wide-angle photoproduction of the ${\eta }^{\prime }$-meson and its gluon content

Abstract

We investigate wide-angle photoproduction of the ${\eta }^{\prime }$ meson within the handbag approach to twist-3 accuracy. It turns out that, due to the gluon content of the ${\eta }^{\prime }$, 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 $\eta -{\eta }^{\prime }$ mixing, we provide prediction for the ${\eta }^{\prime }$ cross section and helicity correlations. It is argued that ${\eta }^{\prime }$ photoproduction is well suited to improve our knowledge of the two-gluon distribution amplitude.

Comments: 18 pages, 5 figures