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

The radiative transitions phi→ηγ and phi→η'γ are analysed using QCD sum-rules. At leading order in perturbative QCD, we obtain the results: Script B(phi→ηγ) = (1.15+/-0.2) 10^-2 and Script B(phi→η'γ) = (1.18+/-0.4) 10^-4, in very good agreement with existing experimental data. The related issue of η-η' mixing is discussed and we give predictions for the η and η' decay constants in the framework of a mixing scheme in the quark-flavour basis.