Evidence for the ηc(2S)→π+π−η decay

Le résumé fourni par la source

The decay ${\ensuremath{\eta}}_{c}(2S)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\eta}$ is searched for through the radiative transition $\ensuremath{\psi}(3686)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\eta}}_{c}(2S)$ using 448 million $\ensuremath{\psi}(3686)$ events accumulated at the BESIII detector. The first evidence of ${\ensuremath{\eta}}_{c}(2S)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\eta}$ is found with a statistical significance of $3.5\ensuremath{\sigma}$. The product of the branching fractions of $\ensuremath{\psi}(3686)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\eta}}_{c}(2S)$ and ${\ensuremath{\eta}}_{c}(2S)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\eta}$ is measured to be $\mathrm{Br}(\ensuremath{\psi}(3686)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\eta}}_{c}(2S))\ifmmode\times\else\texttimes\fi{}\mathrm{Br}({\ensuremath{\eta}}_{c}(2S)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\eta})=\phantom{\rule{0ex}{0ex}}(2.97\ifmmode\pm\else\textpm\fi{}0.81\ifmmode\pm\else\textpm\fi{}0.26)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$, where the first uncertainty is statistical and the second one is systematic. The branching fraction of the decay ${\ensuremath{\eta}}_{c}(2S)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\eta}$ is determined to be $\mathrm{Br}({\ensuremath{\eta}}_{c}(2S)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\eta})=\phantom{\rule{0ex}{0ex}}(42.4\ifmmode\pm\else\textpm\fi{}11.6\ifmmode\pm\else\textpm\fi{}3.8\ifmmode\pm\else\textpm\fi{}30.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$, where the third uncertainty is transferred from the uncertainty of the branching fraction of $\ensuremath{\psi}(3686)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\eta}}_{c}(2S)$.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.