A bstract We study the quantum properties of the Higgs-boson decays into four fermions via two vector bosons ( H → VV * → 4 f ). In particular, we focus on the case of two different-flavour lepton pairs ( H → ZZ * → μ + μ − e + e − ). We compute the quantum-information observables for the corresponding two-qutrit system ( ZZ ) at next-to-leading order electroweak (NLO EW) accuracy in the SM. We find that NLO EW corrections lead to giant (order 1) effects in some specific cases, significantly altering the extraction of observables quantifying the quantum correlations. We identify observables that are robust and can be used to extract reliable information. Finally, we discuss possible new physics (NP) effects, parametrised via an effective-field-theory approach. We show how quantum observables can increase the sensitivity to NP also for the process considered in this study.
Gratta et al. (Mon,) studied this question.