Is eta' partially made of gluonium?

TL;DR

This paper investigates whether the eta' meson contains a significant gluonium component by analyzing radiative decay data, concluding that there is no substantial evidence for gluonium in eta' and providing updated mixing parameters.

Contribution

It provides a phenomenological analysis of radiative decays to determine the gluonic content of eta', finding no significant gluonium contribution and refining mixing angle estimates.

Findings

Gluonium contribution to eta' is negligible, with Z_eta'^2=0.04±0.09.

Mixing angle phi_P is approximately 41.4°, with a small gluonium mixing angle.

No evidence found for a significant gluonic component in eta'.

Abstract

A phenomenological analysis of radiative $V\to P\gamma$ and $P\to V\gamma$ decays is performed in order to determine the gluonic content of the $\eta^\prime$ wave function. Our result shows that there is no evidence for such a gluonium contribution, $Z_{\eta^\prime}^2=0.04\pm 0.09$. In terms of a mixing angle description this corresponds to $\phi_P=(41.4\pm 1.3)^\circ$ and $|\phi_{\eta^\prime G}|=(12\pm 13)^\circ$.