Determination of Spin-Parity Quantum Numbers of X(2370) as 0−+ from J/ψ→γKS0KS0η′

Abstract

Based on $(10087\pm 44)\times {10}^{6}J/\psi$ events collected with the BESIII detector, a partial wave analysis of the decay $J/\psi \to \gamma K_S^0{K}_S^0{\eta }^{\prime }$ is performed. The mass and width of the $X(2370)$ are measured to be $2395\pm 11(\mathrm{stat}{)}_{-94}^{+26}(\mathrm{syst})\mathrm{MeV}/c^2$ and ${188}_{-17}^{+18}(\mathrm{stat}{)}_{-33}^{+124}(\mathrm{syst})\mathrm{MeV}$, respectively. The corresponding product branching fraction is $\mathcal{B}[J/\psi \to \gamma X(2370)]\times \mathcal{B}[X(2370)\to f_0(980){\eta }^{\prime }]\times \mathcal{B}[f_0(980)\to K_S^0{K}_S^0]=(1.31\pm 0.22(\mathrm{stat}{)}_{-0.84}^{+2.85}(\mathrm{syst}))\times {10}^{-5}$. The statistical significance of the $X(2370)$ is greater than $11.7\sigma$ and the spin parity is determined to be $0^{-+}$ for the first time. The measured mass and spin parity of the $X(2370)$ are consistent with the predictions of the lightest pseudoscalar glueball.