Search for the X(2370) and observation of ηc→ηηη′ in J/ψ→γηηη′

Le résumé fourni par la source

Using a sample of $1.31\ifmmode\times\else\texttimes\fi{}{10}^{9}\text{ }\text{ }J/\ensuremath{\psi}$ events collected with the BESIII detector, we perform a study of $J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\eta}\ensuremath{\eta}{\ensuremath{\eta}}^{\ensuremath{'}}$ to search for the $X(2370)$ and ${\ensuremath{\eta}}_{c}$ in the $\ensuremath{\eta}\ensuremath{\eta}{\ensuremath{\eta}}^{\ensuremath{'}}$ invariant mass distribution. No significant signal for the $X(2370)$ is observed, and we set an upper limit for the product branching fraction of $\mathcal{B}(J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\gamma}X(2370)\ifmmode\cdot\else\textperiodcentered\fi{}\mathcal{B}(X(2370)\ensuremath{\rightarrow}\ensuremath{\eta}\ensuremath{\eta}{\ensuremath{\eta}}^{\ensuremath{'}})<9.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ at the 90% confidence level. A clear ${\ensuremath{\eta}}_{c}$ signal is observed for the first time, yielding a product branching fraction of $\mathcal{B}(J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\eta}}_{c})\ifmmode\cdot\else\textperiodcentered\fi{}\mathcal{B}({\ensuremath{\eta}}_{c}\ensuremath{\rightarrow}\ensuremath{\eta}\ensuremath{\eta}{\ensuremath{\eta}}^{\ensuremath{'}})=\phantom{\rule{0ex}{0ex}}(4.86\ifmmode\pm\else\textpm\fi{}0.62(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.45(\mathrm{sys}))\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$.

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