Evidence for ${\eta }_c$(2S)$\to\pipieta$ decay

Abstract

The decay $η_c(2S)\to\pipieta$ is searched for through the radiative transition $\psi (3686)\to \gamma {\eta }_c(2S)$ using 448 million $\psi$(3686) events accumulated at the BESIII detector. The first evidence of ${\eta }_c(2S)\to {\pi }^{+}{\pi }^{-}\eta$ is found with a statistical significance of 3.5$\sigma$. The product of the branching fractions of $\psi (3686)\to \gamma {\eta }_c(2S)$ and $η_c(2S)\to\pipieta$ is measured to be $Br(ψ(3686)\toγη_c(2S))\times Br(η_c(2S)\to\pipieta)=(2.97\pm0.81\pm0.26)\times10^{-6}$, where the first uncertainty is statistical and the second one is systematic. The branching fraction of the decay $η_c(2S)\to\pipieta$ is determined to be $Br(η_c(2S)\to\pipieta)=(42.4\pm11.6\pm3.8\pm30.3)\times10^{-4}$, where the third uncertainty is transferred from the uncertainty of the branching fraction of $\psi (3686)\to \gamma {\eta }_c(2S)$.

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Cited by in corpus (1)

• Measurements of charmonia decays from BESIII