Radiative VPγ transitions and η–η′ mixing

A value for the η–η′ mixing angle is extracted from the data on VPγ transitions using simple quark-model ideas. The set of data covers all possible radiative transitions between the pseudoscalar and vector meson nonets. Two main ingredients of the model are the introduction of flavour-dependent overlaps for the various qq̄ wave functions and the use of the quark-flavour basis to describe the η–η′ system. In this basis the mixing angle is found to be φP=(37.7±2.4)°.