Novel extension of MSSM and "TeV scale" coupling unification

Motivated by the coupling unification problem, we propose a novel extension of the Minimal Supersymmetric Standard Model. One of the predictions of this extension is the existence of new states neutral under SU(3)(c) circle times SU(2), but charged under U(l)(Y). The mass scale for these new states can be around the mass scale of the electroweak Higgs doublets. This suggests the possibility of their detection in the present or near future collider experiments. Unification of gauge couplings in this extension is as precise (at one loop) as in the MSSM, and can occur in the TeV range. (C) 1999 Elsevier Science B.V. All rights reserved.