Search for A to Zh(bb) in ATLAS at 13 TeV

A search for a heavy, CP-odd Higgs boson, A, decaying into a Z boson and a CP-even Higgs boson, h, with a mass of 125 GeV is performed using the ATLAS detector at the Large Hadron Collider. The search uses proton–proton collision data at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 3.2 /fb. Decays of h bosons to bb pairs, where the resulting hadronic jets can be resolved or are merged in the detector, are both considered. Final states of the Z boson decaying to a pair of charged leptons, Z → e+e− and Z → μ+μ−, or into neutrinos, Z → νν, are considered. The data are used to determine 95% confidence level upper limits on the product of production cross-sections and branching fractions, σ(pp → A)·BR(A → Zh)·BR(h → bb) for mA = [200,2000] GeV assuming gluon-fusion or b-quark-associated exclusive production. Results are also interpreted in the context of benchmark models for a two-Higgs doublet extension of the Standard Model.