Prospects of measuring quantum entanglement in $\ddot{I}„\ddot{I}„$ final states at a future $e^{+}{e}^{-}$ Higgs factory

Abstract

We introduce a method to study quantum entanglement at a future $e^{+}{e}^{-}$ Higgs factory (here the Future Circular Collider colliding $e^{+}$ and $e^{-}$ (FCC-ee) operating at $\sqrt{s}=240\mathrm{GeV}$) in the $\ddot{I}„\ddot{I}„$ final state. This method is focused on the $\ddot{I}„\to \ddot{I}€\hat{I}{½}_{\ddot{I}}„$ decay. We show how the introduced method works on simulated events without detector effects. When detector effects are applied, the necessary $\ddot{I}„$ four-momenta can be reconstructed from kinematic constraints. We will discuss the advantages of $e^{+}{e}^{-}$ collisions over $pp$ collisions where the reconstruction of the $\ddot{I}„\ddot{I}„$ rest frame is more difficult. This discussion will focus on the influence of $p_T$ trigger cuts on the visible $\ddot{I}{€}^{\pm }$ in the $\ddot{I}„$ lepton decay.