[论文解读] Searches for new physics beyond the Standard Model in hyperon sector

Jianyu Zhang, Jinlin Fu+1 more|arXiv (Cornell University)|Feb 25, 2026

Particle physics theoretical and experimental studies被引用 0

一句话总结

A BESIII-driven review summarizing hyperon-sector searches for BSM physics, including CP violation via Lambda EDM, baryon/lepton number violation, dark-sector signatures, and invisible decays, with world-leading limits.

ABSTRACT

Hyperon physics offers a distinctive laboratory for probing the intensity frontier and searching for physics beyond the Standard Model. This review summarizes recent results from the BESIII experiment, including pioneering studies of dark baryons, massless BSM particles, and invisible decay modes, together with investigations of baryon- and lepton-number violation. A central highlight is the determination of the $Λ$ electric dipole moment using quantum-entangled hyperon-antihyperon pairs, achieving a sensitivity three orders of magnitude beyond previous limits. These measurements provide world-leading constraints on new physics scenarios and establish a robust foundation for next-generation precision studies. By integrating experimental progress with theoretical developments and future facility prospects, this review emphasizes the critical role of hyperon probes in testing the fundamental laws of nature.

研究动机与目标

• Motivate high-precision, flavor-diagonal probes of CP violation and baryon/lepton-number conservation beyond the SM using hyperons.
• Summarize BESIII results on CP-violating observables, B/L-violating processes, and dark-sector/invisible decays.
• Highlight experimental methods leveraging quantum-entangled hyperon–antihyperon pairs and double-tag techniques.
• Assess implications for BSM parameter spaces and future facility prospects (e.g., STCF).

提出的方法

• Use quantum-entangled J/psi -> hyperon–antihyperon pairs to access polarization observables and CP-violating form factors.
• Extract CP-violating and parity-violating form factors (notably H_T and F_A) from angular correlations in Lambda–antiLambda decays.
• Apply double-tag techniques in J/psi decays to search for invisible decays and rare BNV/LNV channels.
• Employ data-driven background modeling and control samples to set upper limits on rare decays and missing-energy signatures.
• Translate observables into constraints on quark EDM/CEDM parameters and dark-sector effective operators.

实验结果

研究问题

• RQ1 当前 hyperon 系统中对 CP 违反参数的限制，特别是 Lambda EDM 的限制如何，并且它们如何约束奇夷夷（strange-quark） CPV 部分？
• RQ2 Hyperon 衰变是否存在重子数或轻子数违背，它们是否能揭示暗领域或与 Majorana 中微子相关的过程？
• RQ3 通过缺失能量信号，Hyperon 衰变是否能揭示隐形或无质量的暗领域粒子？
• RQ4 Hyperon 为基础的约束与中子/电子基础的 BSM 场景相比如何，未来设施能否提升灵敏度？
• RQ5 关于介导夸克-暗重子转移的暗重子及相关 Wilson 系数的最严格界限是什么？

主要发现

Physics Topic	Observable	Experimental Limit (90% CL)
Dark Baryon Sector	B(Xi^- -> pi^- chi)	4.2 × 10^-5 − 6.5 × 10^-4
Invisible Decay	B(Lambda -> invisible)	7.4 × 10^-5
Massless BSM Particle	B(Sigma^+ -> p + invisible)	3.2 × 10^-5
Λ EDM	|d_Λ|	6.5 × 10^-19 e·cm (95% CL)
Baryon/Lepton Violation	B(Xi^0 -> K^- e^+)	3.6 × 10^-6
Baryon/Lepton Violation	B(Xi^- -> Sigma^+ e^- e^-)	2.0 × 10^-5
Baryon/Lepton Violation	B(Sigma^- -> p e^- e^-)	6.7 × 10^-5
Baryon/Lepton Violation	δm_{ΛΛbar}	3.8 × 10^-18 GeV

• Lambda 超子电矩被约束为 |d_Lambda| < 6.5 × 10^-19 e·cm（95% CL），比之前的限制高出约三个数量级。
• 未观察到 Lambda–antiLambda 振荡信号；振荡参数 delta m_Lambda Lambda < 8 × 10^-18 GeV（90% CL），在 1.31×10^9 个 J/psi 事件中有改进的数据至 delta m < 2.1×10^-18 GeV（90% CL）。
• 对 B/L 违反衰变的搜索给出上限：BXi^0 -> K^- e^+ < 6×10^-6, BXi^0 -> K^+ e^- < 9×10^-6, BSigma^- -> p e^- e^- < 7×10^-5（90% CL）。
• 隐形 Lambda 衰变限制：B(Lambda -> invisible) < 7.4 × 10^-5（90% CL）。
• 在 Sigma^+ -> p + invisible 的质量无关粒子搜索中，B(Sigma^+ -> p + invisible) < 3.2 × 10^-5（90% CL），并约束新粒子对 F_sd^A > 2.8 × 10^7 GeV 的夹持。
• Xi^- -> pi^- + invisible 的暗重子搜索给出质量假设下的界限为 4.5×10^-5 至 6.5×10^-4；若 m_chi = m_Lambda，则 B < 6.5×10^-4（90% CL）。