Glue content and mixing angle of theη−η′system: The effect of the isoscalar0−continuum

Abstract

Masses and topological charges of the $\ensuremath{\eta}$ and ${\ensuremath{\eta}}^{\ensuremath{'}}$ mesons are expressed in terms of the singlet-octet mixing angle $\ensuremath{\theta}$. Contributions of the pseudoscalar ${0}^{\ensuremath{-}}$ continuum are evaluated in a model independent way. Applications to the decay $\ensuremath{\eta}\ensuremath{\rightarrow}3\ensuremath{\pi}$ and to the radiative decay of vector mesons involving $\ensuremath{\eta}$ and ${\ensuremath{\eta}}^{\ensuremath{'}}$ are considered. Agreement with experiment is, in general, good and the results quite stable for $\ensuremath{-}30.5\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\lesssim}\ensuremath{\theta}\ensuremath{\lesssim}\ensuremath{-}18.5\ifmmode^\circ\else\textdegree\fi{}$.