Six-lepton z′ resonance at the large hadron collider

New physics models admit the interesting possibility of a Z′ weak boson associated with an extra U(1) gauge symmetry and a Higgs boson that is heavy enough to decay into a pair of Z bosons. Then Z′ production and decay via Z′→ZH→ZZZ has a distinctive LHC signal that is nearly background-free and reconstructs the H and Z′ masses and widths. The Z′ decay to 3 pairs of leptons is especially distinctive. The ZH decay mode exists even if the Z′ is decoupled from leptons, which motivates an independent 6-lepton resonance search regardless of the dilepton search results.