Local vs. nonlocal entanglement in top-quark pairs at the LHC

TL;DR

This paper investigates the nature of entanglement in top-antitop quark pairs at the LHC, revealing local entanglement near threshold and nonlocal entanglement in boosted regions, with implications for quantum foundations.

Contribution

It distinguishes between local and nonlocal entanglement in top-quark pairs and links these phenomena to specific kinematic regions at the LHC, providing new insights into quantum correlations in high-energy physics.

Findings

Local entanglement near production threshold

Nonlocal entanglement in boosted regions with high invariant mass

Existence of separable states with non-zero discord and magic

Abstract

We show that the entanglement observed in top-antitop quark spin states at the LHC is local in the energy region close to the production threshold. In contrast, nonlocal entanglement is observed in the central boosted region defined by a top-quark pair invariant mass $m_{t\bar t} > 800$ GeV and scattering angles $\Theta$ satisfying $|\cos \Theta |<0.2$. This makes top-quark pairs a unique laboratory for studying the interplay between entanglement and Bell locality. The locality of entanglement near the production threshold is further supported by a recent CMS analysis, which reports a significance of more than $5\sigma$. We also demonstrate that there exists a kinematic region where the spin states of the top-antitop quark are separable, yet they exhibit non-zero discord and magic.