Measurement of the $\eta$ -${\eta }^{\prime }$ mixing angle in ${\pi }^{-}$ and $K^{-}$ beams with GAMS-$4\pi$ Setup

Abstract

The results of mixing angle measurement for ${\eta }^{\prime }$, $\eta$ mesons generated in charge exchange reactions with ${\pi }^{-}$ and $K^{-}$ beams are preseneted. When the ${\eta }^{\prime }$, $\eta$ mesons are described in nonstrange(NS)--strange(S) quark basis the ${\pi }^{-}$ and $K^{-}$ beams allow to study $|{\eta }_q>$ and $|{\eta }_s>$ parts of the meson wave function. The cross section ratio at $t^{\prime }=0$ (GeV/c)${}^2$ in the ${\pi }^{-}$ beam is $R_{\pi }({\eta }^{\prime }/\eta )=0.56\pm 0.04$, results in mixing angle ${\varphi }_P=(36.8\pm 1.{)}^o$. For $K^{-}$ beam the ratio is $R_K({\eta }^{\prime }/\eta )=1.30\pm 0.16$. It was found that gluonium content in ${\eta }^{\prime }$ is ${\sin }^2{\psi }_G=0.15\pm 0.06$. The experiment was carried out with GAMS-4$\pi$ Setup.

Comments: 6 pages, 4 figures, 1 table, to be submitted in European physical journal C. Minor changes, the Bibliography extended