Understanding Bell locality tests at colliders

For decades, it has been known that local hidden variable theories cannot be disproved by collider experiments involving decaying particles. However, if these theories satisfy a small set of mild assumptions, they become testable. In particular, they can be disproved using Bell-like inequalities for ${\mu }^{+}{\mu }^{-}$ and ${\tau }^{+}{\tau }^{-}$ pairs.