Quantum entanglement and Bell inequality violation at colliders

TL;DR

This review explores recent advances in detecting quantum entanglement and Bell inequality violations at particle colliders, analyzing experimental data across various particle systems and discussing implications for physics beyond the Standard Model.

Contribution

It provides a comprehensive overview of the definitions, tools, and recent experimental results in collider-based entanglement studies, highlighting new methods and potential for discovering new physics.

Findings

Entanglement observed in top-quark and B meson decays.

Bell inequality violations detected in collider experiments.

Entanglement as a tool to probe beyond Standard Model physics.

Abstract

The study of entanglement in particle physics has been gathering pace in the past few years. It is a new field that is providing important results about the possibility of detecting entanglement and testing Bell inequality at colliders for final states as diverse as top-quark, $\tau$-lepton pairs and $\Lambda$-baryons, massive gauge bosons and vector mesons. In this review, after presenting definitions, tools and basic results that are necessary for understanding these developments, we summarize the main findings -- as published by the beginning of year 2024 -- including analyses of experimental data in $B$ meson decays and top-quark pair production. We include a detailed discussion of the results for both qubit and qutrits systems, that is, final states containing spin one-half and spin one particles. Entanglement has also been proposed as a new tool to constrain new particles and fields beyond the Standard Model and we introduce the reader to this promising feature as well.