Z ′ Bosons and Supersymmetry 1

A broad class of supersymmetric extensions of the standard model predict a Z ′ vector boson whose mass is naturally in the range 250 GeV<MZ′<2 TeV. To avoid unacceptably large mixing with the Z, one requires either a discrete tuning of the U(1) charges or a leptophobic Z . Both cases are likely to arise as the low energy limits of heterotic string compactifications, but a survey of existing realistic string models provides no acceptable examples. A broken U(1) leads to additional D-term contributions to squark, slepton, and Higgs masses, which depend on the U(1) charge assignments and the Z ′ mass. The Tevatron and future colliders can discover or decisively rule out this class of models. 1 To appear in the Proceedings of the 1996 DPF/DPB Summer Study on New Directions for High Energy Physics (Snowmass 96), Snowmass CO, June 25 July 12, 1996. Research supported by the U.S. Department of Energy under contract DEAC03-76SF00515.