Nat Commun. 2024 Oct 11;15(1):8812. doi: 10.1038/s41467-024-51802-y.
One of the fundamental goals of particle physics is to gain a microscopic understanding of the strong interaction. Electromagnetic form factors quantify the structure of hadrons in terms of charge and magnetization distributions. While the nucleon structure has been investigated extensively, data on hyperons are still scarce. It has recently been demonstrated that electron-positron annihilations into hyperon-antihyperon pairs provide a powerful tool to investigate their inner structure. We present a method useful for hyperon-antihyperon pairs of different types which exploits the cross section enhancement due to the effect of vacuum polarization at the J/ψ resonance. Using the 10 billion J/ψ events collected with the BESIII detector, this allows a precise determination of the hyperon structure function. The result is essentially a precise snapshot of the transition process, encoded in the transition form factor ratio and phase. Their values are measured to be R = 0.860 ± 0.029(stat.) ± 0.015(syst.), and . Furthermore, charge-parity (CP) breaking is investigated in this reaction and found to be consistent with CP symmetry.
粒子物理学的基本目标之一是从微观层面理解强相互作用。电磁形状因子根据电荷和磁化分布来量化强子的结构。虽然对核子结构已进行了广泛研究，但关于超子的数据仍然稀少。最近已证明，正负电子湮灭产生超子 - 反超子对为研究它们的内部结构提供了一个有力工具。我们提出一种对不同类型的超子 - 反超子对有用的方法，该方法利用了在J/ψ共振处真空极化效应导致的截面增强。利用北京谱仪III（BESIII）探测器收集的100亿个J/ψ事例，这使得能够精确测定超子结构函数。结果本质上是跃迁过程的精确快照，编码在跃迁形状因子比和相位中。测得它们的值为R = 0.860 ± 0.029（统计）± 0.015（系统），以及 。此外，在该反应中研究了电荷宇称（CP）破坏，发现其与CP对称性一致。
