Entanglement and Bell inequalities violation in $$H\rightarrow ZZ$$ H → Z Z with anomalous coupling

Abstract

Abstract We discuss entanglement and violation of Bell-type inequalities for a system of two Z bosons produced in Higgs decays. We take into account beyond the Standard Model (anomalous) coupling between H and daughter bosons but we limit ourselves to an overall scalar ZZ state (we exclude the possibility that H contains a pseudo-scalar component). In particular we consider the case when each Z decays further into fermion-antifermion pair. We find that the ZZ state is entangled and violates the CGLMP inequality for all values of the (anomalous) coupling constant. We also discuss the impact of a background on these results. The methods we develop are completely general, since they can be extrapolated to any scalar particle decaying into two spin-1 particles of different masses. Moreover, the violation of the CGLMP inequality in the final state is theoretically ensured for any value of the couplings.