Seminarium "High Energy, Cosmology and Astro-particle Physics (HECA)"

The study of quantum observables at high-energy colliders provides a powerful probe of the quantum structure underlying particle interactions. In this talk, I will begin by outlining the general framework for defining and measuring such observables. I will then discuss the impact of beam polarisation on quantum properties emerging in 2 to 2 fermionic inelastic scattering processes, considering different possible mediators such as scalar, vector, and tensor operators. Focusing on top-antitop pair production at future lepton colliders, I will present analytic results for the spin density matrix and examine a range of quantum information-theoretic quantities, including entanglement, spin correlations, Bell inequality violations, and measures of purity and magic. The overarching goal is to assess how beam polarization can be exploited to probe the quantum character of the t-tbar system and enhance sensitivity to potential new physics effects.