https://doi.org/10.1140/epjc/s10052-006-0129-y
Regular Article - Theoretical Physics
Some properties of the newly observed X(1835) state at BES
1
Department of Physics, Nankai University, Tianjin, P.R. China
2
NCTS/TPE, Department of Physics, National Taiwan University, Taipei, Taiwan
3
Institute of Theoretical Physics, Academia Sinica, Beijing, P.R. China
* e-mail: liuxiang726@mail.nankai.edu.cn
Received:
17
March
2006
Published online:
21
November
2006
Recently the BES collaboration has announced the observation of a resonant state in the π+π-η’ spectrum in J/ψ→γπ+π-η’ decay. Fitting the data with a 0-+ state, the mass is determined to be 1833.7 MeV with 7.7σ statistic significance. This state is consistent with the one extracted from previously reported pp̄ threshold enhancement data in J/ψ→γpp̄. We study the properties of this state using QCD anomaly and QCD sum rules, assuming X(1835) to be a pseudoscalar, and we show that it is consistent with the data. We find that this state has a sizeable matrix element , leading to branching ratios of (2.61–7.37)×10-3 and (2.21–10.61)×10-2 for J/ψ→γGp and for Gp→π+π-η′, respectively. Combining the calculated branching ratio of J/ψ→γGp and data on threshold enhancement in J/ψ→γpp̄, we determine the coupling for the Gp–p–p̄ interaction. We finally study the branching ratios of the other J/ψ→γ+three mesons decay modes. We find that J/ψ→γGp→γ(π+π-η,KKπ0) can provide useful tests for the mechanism proposed.
© Springer-Verlag Berlin Heidelberg, 2007