Precise Measurement of the $\Lambda$ Electric Dipole Moment through the Entangled Strange Baryon-Antibaryon System

Abstract

The dominance of matter over antimatter in the universe has consistently driven the pursuit of new physics beyond the Standard Model that violates charge-parity symmetry. Unlike the well-constrained electrons and neutrons, strange baryons (hyperons) remain a largely unexplored territory, in which interactions between hyperons and particles from new physics could induce a non-trivial electric dipole moment (EDM). However, direct measurements of hyperon EDMs through spin precession are highly challenging due to their short lifetimes. In this paper, we present a novel method to extract the EDM of the lightest hyperon, $\Lambda$, using the entangled $\Lambda$$\overline{\Lambda}$ system. Our result is consistent with zero, achieving a three-order-of-magnitude improvement over the previous upper limit established in the 1980s with comparable statistics, providing stringent constraints on potential new physics.