发表机构
State Key Laboratory of Heavy Ion Science and Technology, Institute of Modern Physics, Chinese Academy of Sciences; University of Chinese Academy of Sciences; Peng Huanwu Collaborative Center for Research and Education, International Institute for Interdisciplinary and Frontiers, Beihang University; School of Physics, Southeast University（中国科学院近代物理研究所重离子科学和技术国家重点实验室; 中国科学院大学; 北京航空航天大学前沿交叉学科研究院彭桓武理论研究协同创新中心; 东南大学物理学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出利用同位旋破坏衰变J/ψ→Σ̄⁰Λ作为灵敏探针，结合色散关系和圈图计算，定量研究类时超子电磁形状因子中的双光子交换效应，并预测可观测量特征及不确定性。
AI 中文摘要
虽然双光子交换（TPE）效应在类空核子电磁形状因子中已被广泛研究了二十多年，但它们在类时区域的表现尚未被明确确立。我们提出同位旋破坏衰变$J/\psi \to \bar{\Sigma}^{0}\Lambda$及其电荷共轭过程，作为探测类时超子电磁形状因子中TPE贡献的灵敏探针。该通道通过灵敏且稳健的极化和自旋关联可观测量，为分离TPE效应提供了一个干净的实验室，这些可观测量尤其因$\Lambda$-$\Sigma^0$质量劈裂而增强。结合单光子交换贡献的色散关系分析与TPE振幅的显式圈图计算，我们对阈值区域的TPE效应进行了定量研究。我们的结果表明，所考虑的可观测量能够提供TPE贡献的明确特征，并给出了其大小及相应理论不确定性的预测。
英文摘要
While two-photon exchange (TPE) effects in space-like nucleon electromagnetic form factors have been extensively studied for over two decades, their manifestations in the time-like region have yet to be definitively established. We propose the isospin-violating decay $J/ψ\to \barΣ^{0}Λ$ and its charge-conjugate process as a sensitive probe of TPE contributions to time-like hyperon electromagnetic form factors. This channel provides a clean laboratory for isolating TPE effects through sensitive and robust polarization and spin-correlation observables, which are particularly enhanced by the $Λ$-$Σ^0$ mass splitting. Combining a dispersion-relation analysis of the one-photon-exchange contribution with explicit loop calculations of the TPE amplitudes, we perform a quantitative study of TPE effects in the threshold region. Our results demonstrate that the considered observables can provide unambiguous signatures of TPE contributions and present predictions for their size together with the associated theoretical uncertainties.
Comments12 pages, 8 figures
