252 Search Results

Using a sample of 1.31 × 10⁹ J/ψ events collected with the BESIII detector, we perform a study of J/ψ → γKK¯η'. X(2370) is observed in the KK¯η' invariant-mass distribution with a statistical significance of 8.3σ. Its resonance parameters are measured to be M = 2341.6 ± 6.5(stat.) ± 5.7(syst.) MeV/c² and Γ = 117 ± 10(stat.) ± 8(syst.) MeV. The product branching fractions for J/ψ → γX(2370), X(2370) → K⁺K^–η' and J/ψ → γX(2370), X(2370) → $$K$$ $$^{0}_{S}$$ $$K$$ $$^{0}_{S}$$η' are determined to be (1.79 ± 0.23(stat.) ± 0.65(syst.)) × 10^–5 and (1.18 ± 0.32(stat.) ± 0.39(syst.)) × 10^–5,more » respectively. No evident signal for X(2120) is observed in the KK¯η' invariant-mass distribution. The upper limits for the product branching fractions of B(J/ψ → γX(2120) → γK⁺K^–η') and B(J/ψ → γX(2120) → $$K$$ $$^{0}_{S}$$ $$K$$ $$^{0}_{S}$$η') are determined to be 1.49 × 10^–5 and 6.38 × 10^–6 at the 90% confidence level, respectively.« less

There has recently been a dramatic renewal of interest in hadron spectroscopy and charm physics. This renaissance has been driven in part by the discovery of a plethora of charmonium-like XYZ states at BESIII and B factories, and the observation of an intriguing proton-antiproton threshold enhancement and the possibly related X(1835) meson state at BESIII, as well as the threshold measurements of charm mesons and charm baryons. We present a detailed survey of the important topics in tau-charm physics and hadron physics that can be further explored at BESIII during the remaining operation period of BEPCII. This survey will helpmore » in the optimization of the data-taking plan over the coming years, and provides physics motivation for the possible upgrade of BEPCII to higher luminosity.« less