On the gluon content of the eta and eta' mesons

Abstract

A phenomenological analysis of radiative $V\to Pγ$ and $P\to Vγ$ decays is performed with the purpose of determining the gluonic content of the $η$ and $η^\prime$ wave functions. Our results show that within our model there is no evidence for a gluonium contribution in the $η$, $Z_η^2=0.00\pm 0.12$, or the $η^\prime$, $Z_{η^\prime}^2=0.04\pm 0.09$. In terms of a mixing angle description this corresponds to $ϕ_P=(41.4\pm 1.3)^\circ$ and $|ϕ_{η^\prime G}|=(12\pm 13)^\circ$. In addition, the $η$-$η^\prime$ mixing angle is found to be $ϕ_P=(41.5\pm 1.2)^\circ$ if we don't allow for a gluonium component.