Radiative phi-meson decays and η−η′ mixing: a QCD sum rule analysis

The radiative transitions $\phi \to \eta \gamma$ and $\phi \to \eta^\prime\gamma$ are analysed using QCD sum-rules. The results we obtain for ${\calB}(\phi \to \eta \gamma)=(1.15 \pm 0.2) 10^{-2}$ and ${\cal B}(\phi \to\eta^\prime \gamma)=(1.18 \pm 0.4) 10^{-4}$ are in very good agreement withexisting experimental data. The related issue of $\eta-\eta^\prime$ mixing isdiscussed and we give predictions for the $\eta$ and $\eta^\prime$ decayconstants in the framework of a mixing scheme in the quark-flavour basis.Comment: Latex, 15 pages, 3figures. Some typos correcte