The top quark in 2025 -- International year of Quantum Science and Technology
J. A. Aguilar-Saavedra
TL;DR
The paper argues that collider-scale top-quark processes provide a novel arena to test quantum mechanics at high energies. It surveys experimental advantages of the top quark, outlines theoretical motivations linked to the hierarchy problem, and reviews measurements of spin correlations and entanglement in $t\bar t$ production. It then analyzes the potential to probe post-quantum correlations, including CHSH-type tests in boosted-top kinematics and the Tsirelson bound $2\sqrt{2}$, as well as the possibility of post-decay entanglement in top decays. By extending foundational quantum tests to the energy frontier, the work highlights a complementary pathway to explore physics beyond the SM and the foundations of QM.
Abstract
Since its discovery at the Tevatron in 1995, the top quark has been extensively studied due to its unique properties. We discuss how the remarkable progress in top-quark physics has opened the possibility of using the top quark as a tool to test quantum mechanics at the energy frontier. After reviewing the motivations for exploring beyond quantum mechanics, we present an example: probing post-quantum correlations at the energy frontier with boosted top quarks.