Some properties of the newly observed X(1835) state at BES

Recently the BES collaboration has announced observation of a resonant state in the ${\pi }^{+}{\pi }^{-}{\eta }^{\mathrm{\prime }}$ spectrum in $J\mathrm{/}\psi \to \gamma {\pi }^{+}{\pi }^{-}{\eta }^{\mathrm{\prime }}$ decay. Fitting the data with a $0^{-+}$ state, the mass is determined to be 1833.7 MeV with $7.7\sigma$ statistic significance. This state is consistent with the one extracted from previously reported $p\bar{p}$ threshold enhancement data in $J\mathrm{/}\psi \to \gamma p\bar{p}$. We study the properties of this state using QCD anomaly and QCD sum rules assuming X(1835) to be a pseudoscalar and show that it is consistent with data. We find that this state has a sizeable matrix element $<0\mathrm{\mid }G\tilde{G}\mathrm{\mid }{G}_p>$ leading to branching ratios of $(2.61\sim 7.37)\times {10}^{-3}$ and $(2.21\sim 10.61)\times {10}^{-2}$ for $J\mathrm{/}\psi \to \gamma G_p$ and for $G_p\to {\pi }^{+}{\pi }^{-}{\eta }^{\mathrm{\prime }}$, respectively. Combining the calculated branching ratio of $J\mathrm{/}\psi \to \gamma G_p$ and data on threshold enhancement in $J\mathrm{/}\psi \to \gamma p\bar{p}$, we determine the coupling for $G_p-p-\bar{p}$ interaction. We finally study branching ratios of other $J\mathrm{/}\psi \to \gamma +threemesons$ decay modes. We find that $J/\psi \to \gamma G_p \to \gamma (\pi^+\pi^- \eta, K K \pi^0)$ can provide useful tests for the mechanism proposed.