
Test of Local Realism via Entangled ΛΛ System
The BESIII Collaboration has achieved a landmark violation of Bell inequalities using entangled hyperon pairs, marking a pivotal test of quantum nonlocality in high-energy physics. Published in Nature Communications (Nat. Commun., 16, 4948 (2025)), the study uses (10.087 ± 0.044) × 10⁹ J/ψ events accumulated at BEPCII/BESIII to probe the ΛΛ entangled system produced in J/ψ→ γηc , and ηc → γΛΛ decays.