Flavor “conservation” and hierarchy in TeV-scale supersymmetric standard model

Abstract

Recently a TeV-scale Supersymmetric Standard Model (TSSM) was proposed in which the gauge coupling unification is as precise (at one loop) as in the MSSM, and occurs in the TeV range. Proton stability in the TSSM is due to an anomaly free z 3 ⊗ 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 flavor gauge symmetries (based on a left-right product tetrahedral group) which together with a “vector-like” Abelian (discrete) flavor gauge symmetry suppresses dangerous higher dimensional operators corresponding to flavor changing neutral currents (FCNCs) to an acceptable level. Discrete flavor gauge symmetries are more advantageous compared with continuous flavor gauge symmetries as the latter must be broken, which generically results in unacceptably large gauge mediated flavor violation. In contrast, in the case of discrete 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 sources of flavor violation, however, are adequately suppressed by the above flavor gauge symmetries for the string scale ∼ 10–100 TeV.