Search for the $X(2370)$ and observation of $\eta_{c}\to\eta\eta\eta^\prime$ in $J/\psi\to\gamma\eta\eta\eta^{\prime}$

TL;DR

This study searches for the $X(2370)$ resonance and observes the $ ext{eta}_c$ decay into $ ext{eta} ext{eta} ext{eta}^ ext{'}$ in $J/ ext{psi}$ decays, setting upper limits on the former and measuring the latter's branching fraction.

Contribution

First observation of $ ext{eta}_c$ decay into $ ext{eta} ext{eta} ext{eta}^ ext{'}$ and the establishment of an upper limit for the $X(2370)$ in $J/ ext{psi}$ decays.

Findings

No significant $X(2370)$ signal observed.

First observation of $ ext{eta}_c o ext{eta} ext{eta} ext{eta}^ ext{'}$ decay.

Measured $ ext{eta}_c$ decay branching fraction as $(4.86 extpm0.62 ext{(stat.)} extpm0.45 ext{(sys.)}) imes10^{-5}$.

Abstract

Using a sample of $1.31\times10^{9} ~J/\psi$ events collected with the BESIII detector, we perform a study of $J/\psi\to\gamma\eta\eta\eta^{\prime}$ to search for the $X(2370)$ and $\eta_{c}$ in the $\eta\eta\eta^{\prime}$ invariant mass distribution. No significant signal for the $X(2370)$ is observed, and we set an upper limit for the product branching fraction of ${\cal B}(J/\psi\to\gamma X(2370)\cdot{\cal B}(X(2370)\to\eta\eta\eta^{\prime}) < 9.2\times10^{-6}$ at the 90% confidence level. A clear $\eta_{c}$ signal is observed for the first time, yielding a product branching fraction of ${\cal B}(J/\psi\to \gamma\eta_{c})\cdot{\cal B}(\eta_{c}\to \eta\eta\eta^{\prime}) = (4.86\pm0.62~({\rm stat.})\pm0.45~({\rm sys.}))\times10^{-5}$.