Radiative transitions involving neutral mesons with $J^P=0^{-} [\eta , {\eta }^{\prime }, \iota \mathrm{}(1440\left)\right] \mathrm{and} 2^{+} [f, f^{\prime }, \theta \mathrm{}(1640\left)\right]$ are used to provide information on the light-quark content of these mesons, and to test predictions of models in which these states are quarkonium-gluonium mixtures. Some suggested observations include (1) $\phi \to {\eta }^{\prime }\gamma$, predicted to have a branching ratio of 7×${10}^{-5\mathrm{}}$ in the standard quarkonium picture of ${\eta }^{\prime }$, (2) $f^{\prime }\to \gamma \gamma$, predicted to have a partial width ≳200 eV if $f^{\prime }=s\overline{s}$ but very sensitive to possible destructive interference from small nonstrange-quark admixtures, and (3) $\iota \mathrm{}\left(1440\right)\mathrm{}\to \gamma \gamma$ and $\theta \mathrm{}\left(1640\right)\mathrm{}\to \gamma \gamma$, which will be easily detectable unless these states are almost totally free of quarkonium admixtures.

• Received 26 July 1982

DOI:https://doi.org/10.1103/PhysRevD.27.1101