Hidden sector or dark sector states appear in many extensions to the Standard Model, to provide a candidate for the darkmatter in the universe or to explain astrophysical observations of positron excesses. A hidden or dark sector can be introduced with an additional U(1)_d dark gauge symmetry. The presence of the dark sector could be inferred either from deviations from the SM-predicted rates of Drell-Yan (DY) events or from Higgs boson decays through exotic intermediate states. The discovery of the Higgs boson during Run 1 of the Large Hadron Collider opens a new and rich experimental program that includes the search for exotic decays H —> Z Zdark —> 4l and H —> Zdark Zdark —> 4l, where Zdark is a dark vector boson.