Observation of $\psi (3686)\to \Lambda \bar{\Lambda }{\eta }^{\prime }$ decay

Abstract

Using a sample of $(27.12\pm 0.14)\times 10^8$ $\psi (3686)$ events collected with the BESIII detector, the decay $\psi (3686)\to \Lambda \bar{\Lambda }{\eta }^{\prime }$ with ${\eta }^{\prime }$ subsequently decaying into $\gamma {\pi }^{+}{\pi }^{-}$ and $\eta {\pi }^{+}{\pi }^{-}$ is observed for the first time. The branching fraction of $\psi (3686)\to \Lambda \bar{\Lambda }{\eta }^{\prime }$ is measured to be $(7.34\pm 0.94(stat.)\pm 0.43(sys.))\times 10^{-6}$. No resonant structures are evident in the $\Lambda {\eta }^{\prime }$, $\bar{\Lambda }{\eta }^{\prime }$ and $\Lambda \bar{\Lambda }$ mass spectra.

11 page, 13 Figures