Improved tests of entanglement and Bell inequalities with LHC tops

TL;DR

This paper proposes new methods to improve the detection of quantum entanglement and Bell inequality violations in top quark pairs produced at the LHC by optimizing observables and event selection strategies.

Contribution

It introduces novel observables and a simple velocity cut to enhance entanglement signals and Bell inequality sensitivity in top pair production at the LHC.

Findings

Enhanced entanglement observables near threshold

Increased Bell inequality sensitivity by up to a factor of 7

Effective suppression of background subprocesses

Abstract

We discuss quantum entanglement in top pair production at the LHC. Near the $t \bar t$ threshold, entanglement observables are enhanced by suppressing the contribution of $q \bar q$ subprocesses, which is achieved by a simple cut on the velocity of the $t \bar t$ system in the laboratory frame. Furthermore, we design new observables that directly measure the relevant combinations of $t\bar t$ spin correlation coefficients involved in the measurement of entanglement and Bell inequalities. As a result, the statistical sensitivity is enhanced, up to a factor of 7 for Bell inequalities near threshold.