Locality in collider tests of Quantum Mechanics with top quark pairs

Tests of quantum properties of fundamental particles in high energy colliders are starting to appear. However, such experiments may suffer from the locality loophole. We argue for criteria that take into account the space-like separation between measurements for the case of spin correlations in top quark pairs produced at the LHC. We derive bounds considering three different definitions of what constitutes the quantum measurement - the decay of top quarks, the decay of W bosons, and the stable decay products contacting a macroscopic device.