Flavor "conservation" and hierarchy in TeV-scale supersymmetric standard model

Recently a TeV-scale Supersymmetric Standard Model (TSSM) was proposed in w hich the gauge coupling unification is as precise (at one loop) as in the M SSM, and occurs in the TeV range. Proton stability in the TSSM is due to an anomaly free Z(3) x Z(3) discrete gauge symmetry, which is also essential for successfully generating neutrino masses in the desirable range. In this paper we show that the TSSM admits anomaly free non-Abelian discrete flavo r gauge symmetries (based on a left-right product tetrahedral group) which together with a "vector-like" Abelian (discrete) flavor gauge symmetry supp resses dangerous higher dimensional operators corresponding to flavor chang ing neutral currents (FCNCs) to an acceptable level. Discrete flavor gauge symmetries are more advantageous compared with continuous flavor gauge symm etries as the latter must be broken, which generically results in unaccepta bly large gauge mediated flavor violation. In contrast, in the case of disc rete flavor gauge symmetries the only possibly dangerous sources of flavor violation either come from the corresponding "bulk" flavon (that is, flavor symmetry breaking Higgs) exchanges, or are induced by flavon VEVs. These s ources of flavor violation, however, are adequately suppressed by the above flavor gauge symmetries for the string scale similar to 10-100 TeV. (C) 19 99 Elsevier Science B.V, All rights reserved.