Institute of High Energy Physics, Beijing 100049, People's Republic of China.
G.I. Budker Institute of Nuclear Physics SB RAS (BINP), Novosibirsk 630090, Russia.
Phys Rev Lett. 2018 Jun 15;120(24):242003. doi: 10.1103/PhysRevLett.120.242003.
Using a low background data sample of 9.7×10^{5} J/ψ→γη^{'}, η^{'}→γπ^{+}π^{-} events, which are 2 orders of magnitude larger than those from the previous experiments, recorded with the BESIII detector at BEPCII, the decay dynamics of η^{'}→γπ^{+}π^{-} are studied with both model-dependent and model-independent approaches. The contributions of ω and the ρ(770)-ω interference are observed for the first time in the decays η^{'}→γπ^{+}π^{-} in both approaches. Additionally, a contribution from the box anomaly or the ρ(1450) resonance is required in the model-dependent approach, while the process specific part of the decay amplitude is determined in the model-independent approach.
利用 BESIII 探测器在 BEPCII 上记录的 9.7×10^{5} J/ψ→γη^{'}，η^{'}→γπ^{+}π^{-}事件的低本底数据样本，其数量级比以前的实验大两个数量级，通过模型相关和模型独立两种方法研究了 η^{'}→γπ^{+}π^{-}的衰变动力学。首次在这两种方法中观察到 η^{'}→γπ^{+}π^{-}衰变中 ω 和 ρ(770)-ω 干涉的贡献。此外，在模型相关方法中需要来自盒异常或 ρ(1450)共振的贡献，而在模型独立方法中则确定了衰变振幅的过程特定部分。
