北京谱仪BESIII精确测量Y(4260)粒子

Precise measurement of the Y(4260) particle at the Beijing spectrometer BESIII

利用北京谱仪BESIII实验采集的约9 fb^(-1)数据样本,BESIII测量了e^+e^-→π^+π^- J/ψ过程的产生截面,并对在该过程中观测到的Y(4260)粒子的质量和宽度做了目前世界上最精确的测量。BESIII的测量给出Y(4260)粒子的质量在4.22 GeV/c^2左右,比之前的测量偏低;宽度约44 MeV,比之前的测量窄很多。相比之前的实验,BESIII对Y(4260)粒子参数的精确测量给解释该粒子的理论模型提供了更强的约束。另外,BESIII实验在4.32 GeV/c^2附近还观测到一个新粒子信号,信号显著性为7.6σ。新粒子的质量和宽度和之前观测到的Y(4360)粒子的质量和宽度在误差范围内吻合,有可能是同一个粒子。

Using 9fb-1 data collected with the BESIII spectrometer at the Beijing Electron Positron Collider II storage ring,the production cross section of the e＋e-→π＋π-J/ψ process was measured.We observed the Y（4260） resonance and measured its parameters with the best precision to date in the world.Our measurement shows that the mass of Y（4260） is around 4.22 GeV/c2 and its width is about 44 MeV,which are lower and much narrower,respectively,than previous measurements.BESIII＇s precise measurement sets a tighter constraint on the interpretation of the Y（4260） internal structure models compared with previous experiments.In addition,BESIII also observed a new resonance near 4.32 GeV/c2,with a statistical significance of 7.6σ.The mass and width of this resonance agree with the Y（4360） state within experimental error.