Narrow Results

We study the production line shape of $B^{\ast }\bar{B}$ near threshold, where the $B^{\ast }\bar{B}$ pair comes from the resonance $X_b$. Our study shows that the line shape depends sensitively on the binding energy and the probability of finding an elementary state in the physical bound state. Both of the two parameters are crucial to identify the structure of $X_b$. Therefore, the line shape measurement can shed light on the structure of $X_b$.

The cross-section of $e^{+}{e}^{-}\to K^{+}{K}^{-}J/\psi$ has been measured by BESIII experiment, two enhancements are seen around 4.2 GeV and 4.5 GeV. We try to fit the cross-section with coherent sum of two Breit–Wigner functions, the fit results show $e^{+}{e}^{-}\to K^{+}{K}^{-}J/\psi$ line shape can be described by $Y(4220)$ and a new structure around 4.5 GeV, also can be described by the known charmonium $\psi (4160)$ and $\psi (4415)$. Based on current data, we cannot distinguish which explanation is right. More measurements around 4.2 GeV and 4.5 GeV are desired to improve the understanding of the structures in $e^{+}{e}^{-}\to K^{+}{K}^{-}J/\psi$.

We reported the study of Y(2175) in J/ψ decays, the results from a partial wave analysis of and the observation of charged κ, based on 5.8×10⁷J/ψ events collected at BESII. We also reported the precision R values at the energy points of 2.60, 3.05 and 3.65 GeV/c² and the measurement of the line shape for the cross sections of e⁺e^- → hadrons in the energy range of 3.650 - 3.872 GeV/c². The status of BESIII running, as well as the preliminary results from BESIII are also presented.