Search for heavy resonances decaying into a pair of Z bosons in the ℓ ⁺ℓ ^–ℓ '⁺ℓ '^– and ℓ ⁺ℓ ^–ν ν̅ final states using 139 fb^–1 of proton-proton collisions at √s = 13 TeV with the ATLAS detector

A search for heavy resonances decaying into a pair of Z bosons leading to ℓ⁺ℓ⁻ℓ′⁺ℓ′⁻ and ℓ⁺ℓ⁻ν ν̅  final states, where ℓ stands for either an electron or a muon, is presented. The search uses proton–proton collision data at a centre-of-mass energy of 13 TeV collected from 2015 to 2018 that corresponds to the integrated luminosity of 139 fb⁻¹ recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. Different mass ranges spanning 200 GeV to 2000 GeV for the hypothetical resonances are considered, depending on the final state and model. In the absence of a significant observed excess, the results are interpreted as upper limits on the production cross section of a spin-0 or spin-2 resonance. The upper limits for the spin-0 resonance are translated to exclusion contours in the context of Type-I and Type-II two-Higgs-doublet models, and the limits for the spin-2 resonance are used to constrain the Randall–Sundrum model with an extra dimension giving rise to spin-2 graviton excitations.