Eta-eta' mixing from V->Pgamma and J/psi->VP decays

Abstract

The $\eta$-${\eta }^{\prime }$ pseudoscalar mixing angle and the gluonium content of the ${\eta }^{\prime }$ meson are deduced from an updated phenomenological analysis of $V\to P\gamma$ and $J/\psi \to VP$ decays. In absence of gluonium, the value of the mixing angle in the quark-flavour basis is found to be ${\varphi }_P=(41.5\pm 1.2{)}^{\circ }$ from $V\to P\gamma$ and ${\varphi }_P=(40.5\pm 2.4{)}^{\circ }$ from $J/\psi \to VP$. In presence of gluonium, the values for the mixing angle and the gluonic content of the ${\eta }^{\prime }$ wave function are ${\varphi }_P=(41.4\pm 1.3{)}^{\circ }$ and $Z_{{\eta }^{\prime }}^2=0.04\pm 0.09$ from $V\to P\gamma$ and ${\varphi }_P=(44.5\pm 4.3{)}^{\circ }$ and $Z_{{\eta }^{\prime }}^2=0.28\pm 0.21$ from $J/\psi \to VP$, respectively.

Comments: 8 pages, uses appolb style. Talk presented at the Symposium on Meson Physics, Cracow, Poland, 1-4 October 2008