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

TL;DR

This paper introduces a novel entanglement-based method to measure the $ ext{Lambda}$ hyperon's electric dipole moment, significantly improving the upper limit and constraining new physics beyond the Standard Model.

Contribution

It proposes a new technique using entangled hyperon-antihyperon pairs to measure the $ ext{Lambda}$ EDM, overcoming short lifetime challenges of hyperons.

Findings

Result is consistent with zero EDM.

Achieves a three-order-of-magnitude improvement over previous limits.

Provides stringent constraints on new physics models.

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.