Phenomenological Evidence for the Gluon Content of $\eta$ and ${\eta }^{\prime }$

Patricia Ball, J. -M. Frere, M. Tytgat

We discuss the effect of $\eta$--${\eta }^{\prime }$ mixing and of axial current anomalies on various decay processes. We describe the 2$\gamma$ decays of $\eta$ and ${\eta }^{\prime }$, the radiative decays of low-lying…