Abstract
Using a sample of \(1.31\times 10^{9} ~J/\psi \) events collected with the BESIII detector, we perform a study of \(J/\psi \rightarrow \gamma K{\bar{K}}\eta '\). X(2370) is observed in the \(K{\bar{K}}\eta '\) invariant-mass distribution with a statistical significance of \(8.3\sigma \). Its resonance parameters are measured to be \(M=2341.6\pm 6.5 \, \text {(stat.)} \pm 5.7 \, \text {(syst.)}~ \hbox {MeV}/c^{2}\) and \(\Gamma = 117\pm 10 \, \text {(stat.)}\pm 8 \, \text {(syst.)}~\hbox {MeV}\). The product branching fractions for \(J/\psi \rightarrow \gamma X(2370),X(2370)\rightarrow K^{+}K^{-}\eta '\) and \(J/\psi \rightarrow \gamma X(2370),X(2370)\rightarrow K_{S}^{0}K_{S}^{0}\eta '\) are determined to be \((1.79\pm 0.23\, \text {(stat.)}\pm 0.65\,\text {(syst.)})\times 10^{-5}\) and \((1.18\pm 0.32\, \text {(stat.)}\pm 0.39\, \text {(syst.)})\times 10^{-5}\), respectively. No evident signal for X(2120) is observed in the \(K{\bar{K}}\eta '\) invariant-mass distribution. The upper limits for the product branching fractions of \({\mathcal {B}}(J/\psi \rightarrow \gamma X(2120)\rightarrow \gamma K^{+} K^{-} \eta ')\) and \({\mathcal {B}}(J/\psi \rightarrow \gamma X(2120)\rightarrow \gamma K_{S}^{0} K_{S}^{0} \eta ')\) are determined to be \(1.49\times 10^{-5}\) and \(6.38\times 10^{-6}\) at the 90% confidence level, respectively.
