Search for a heavy Higgs boson decaying into a Z boson and another heavy Higgs boson in the [Formula omitted] and [Formula omitted] final states in pp collisions at [Formula omitted] [Formula omitted] with the ATLAS detector

A search for a heavy neutral Higgs boson, A, decaying into a Z boson and another heavy Higgs boson, H, is performed using a data sample corresponding to an integrated luminosity of 139 fb [Formula omitted] from proton-proton collisions at [Formula omitted] [Formula omitted] recorded by the ATLAS detector at the LHC. The search considers the Z boson decaying into electrons or muons and the H boson into a pair of b-quarks or W bosons. The mass range considered is 230-800 [Formula omitted] for the A boson and 130-700 [Formula omitted] for the H boson. The data are in good agreement with the background predicted by the Standard Model, and therefore 95% confidence-level upper limits for [Formula omitted] are set. The upper limits are in the range 0.0062-0.380 pb for the [Formula omitted] channel and in the range 0.023-8.9 pb for the [Formula omitted] channel. An interpretation of the results in the context of two-Higgs-doublet models is also given.