利用纠缠的超子反超子对精确测量物质-反物质不对称性
Precise Measurement of Matter-Antimatter Asymmetry with Entangled Hyperon Antihyperon Pairs
AI总结:
该研究通过使用BESIII实验收集的10087±44×10^6个J/ψ事件,利用九维螺旋度振幅拟合e^+e^-→J/ψ→Ξ^-Ξ^+及后续衰变,精确测量了Ξ^-和Ξ^+的衰变参数,以及强相位差和弱相位差,并确定了CP不对称性观测量,这些结果是目前最精确的测量。
摘要:
利用纠缠的Ξ^-反Ξ^+对系统,通过收集10087±44×10^6个J/ψ事件,进行CP破坏的搜索。使用九维螺旋度振幅拟合e^+e^-→J/ψ→Ξ^-反Ξ^+及后续衰变。Ξ^-和Ξ^+的衰变参数比目前最好的结果有更高的精度。此外,强相位差(δ_P-δ_S)=(0.3±1.2±0.2)×10^-2 rad和弱相位差(ξ_P-ξ_S)=(-0.2±1.2±0.1)×10^-2 rad被直接确定。这些是到目前为止最精确的测量。CP不对称性观测量A_{CP}^Ξ=(-7.8±4.8±0.8)×10^-3和Δϕ_{CP}^Ξ=(0.6±5.1±0.2)×10^-3 rad被确定,这些结果与CP守恒一致。此外,还独立测量了Λ衰变参数和CP不对称性观测量A^Λ_{CP}=(-2.9±4.3±0.7)×10^-3,这些结果与之前的测量一致,但精度有了显著提高。
英文摘要:
A search for $CP$ violation with an entangled system of $Ξ^-\barΞ^+$ pairs is performed, using $(10,087\pm44)\times10^{6}$ $J/ψ$ events collected with the BESIII experiment. A nine-dimensional helicity amplitude is used to fit $e^+e^- \to J/ψ\toΞ^-\barΞ^+$ and its subsequent decays. The $Ξ^-$ and $Ξ^+$ decay parameters are determined with higher precision compared to the best results reported so far. Furthermore, the strong phase difference, $(δ_P-δ_S)=(0.3\pm1.2\pm0.2)\times10^{-2}~\text{rad}$, and the weak phase difference, $(ξ_P-ξ_S)=(-0.2\pm1.2\pm0.1)\times10^{-2}~\text{rad}$, are directly determined. These are the most precise measurements to date. The $CP$ asymmetry observables $A_{CP}^Ξ=(-7.8\pm4.8\pm0.8)\times10^{-3}$ and $Δϕ_{CP}^Ξ=(0.6\pm5.1\pm0.2)\times10^{-3}~\text{rad}$ are determined, which are consistent with $CP$ conservation. In addition, independent measurements of the $Λ$ decay parameter and $CP$ asymmetry $A^Λ_{CP}=(-2.9\pm4.3\pm0.7)\times10^{-3}$ are also obtained, which are in agreement with the previous measurements, but with much improved precision.
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