Mixing of η-η′ mesons in Jψ decays into a vector and a pseudoscalar meson

The octet-singlet mixing angle θP in the pseudoscalar meson nonet is deduced from the rich set of accurate data on Jψ decays into a vector and a pseudoscalar meson. Corrections due to non-ideal ω-φ mixing have been included for the first time and turn out to be crucial to find θP = −16.9° ± 1.7°, which is appreciably less negative than previous results coming from similar analyses.