Observation of the $X(2370)$ in $J/\ddot{I}ˆ\to {\hat{I}}^3{K}_S^0{K}_S^0\ddot{I}{€}^0$ and $J/\ddot{I}ˆ\to {\hat{I}}^3\ddot{I}{€}^0\ddot{I}{€}^0\hat{I}\cdot$

Abstract

Based on $(10087\pm 44)\times 10^6$ $J/\ddot{I}ˆ$ events collected with the BESIII detector, the $J/\ddot{I}ˆ\to {\hat{I}}^3{K}_S^0{K}_S^0\ddot{I}{€}^0$ and $J/\ddot{I}ˆ\to {\hat{I}}^3\ddot{I}{€}^0\ddot{I}{€}^0\hat{I}\cdot$ processes are studied. The $X(2370)$ is observed in both the $K_S^0{K}_S^0\ddot{I}{€}^0$ and $\ddot{I}{€}^0\ddot{I}{€}^0\hat{I}\cdot$ invariant mass spectra, with statistical significances greater than $14\ddot{I}ƒ$ and $20\ddot{I}ƒ$, respectively. Combining measurements from these processes with measurements from the previously reported $J/\ddot{I}ˆ\to {\hat{I}}^3{K}_S^0{K}_S^0\hat{I}{\cdot }^{\prime }$ process, the mass and width of the $X(2370)$ are determined to be $2359_{-14}^{+13}\text{MeV}/c^2$ and $170_{-29}^{+44}\text{MeV}$, respectively. In addition, the decay $X(2370)\to a_0(980{)}^0\ddot{I}{€}^0$ with $a_0(980{)}^0\to \ddot{I}{€}^0\hat{I}\cdot$ is observed with a statistical significance exceeding $9\ddot{I}ƒ$. The similarities in decay modes between the $X(2370)$ and $\hat{I}{\cdot }_c$ are consistent with the features of a pseudoscalar glueball.