TeV-scale supersymmetric standard model and brane world

Recently we proposed a TeV-scale Supersymmetric Standard Model in which the gauge coupling unification is as precise (at one loop) as in the MSSM, and occurs in the TeV range. One of the key ingredients of this model is the p resence of new states neutral under SU(3)(c) x SU(2)(w) but charged under U (1)(y) whose mass scale is around that of the electroweak Higgs doublets. I n this paper we show that the introduction of these states allows us to gau ge novel anomaly free discrete las well as continuous) symmetries (similar to "lepton" and "baryon" numbers) which suppress dangerous higher dimension al operators and stabilize the proton. Furthermore, the mass hierarchy betw een the up and down quarks (e.g. t versus b) can be explained without appea ling to large tan beta, and the mu-term for the electroweak Higgs doublets las well as for the new states) can be generated, We also discuss various p henomenological implications of our model which lead to predictions testabl e in the present or near future collider experiments. In particular, we poi nt out that signatures of scenarios with high versus low unification (strin g) scale might be rather different. This suggests the possibility that the collider experiments may distinguish between these scenarios even without a direct production of heavy Kaluza-Klein or string states. (C) 1999 Elsevie r Science B.V. All rights reserved.