Measurements of the Mass and Full-Width of the ${\eta }_c$ Meson

J. Z. Bai

In a sample of 58 million $J/\psi$ events collected with the BES II detector, the process J/$\psi \to \gamma {\eta }_c$ is observed in five different decay channels: $\gamma K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}$, $\gamma {\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}$,…