Third Family Quark-Lepton Unification at the TeV Scale

Abstract

We construct a model of quark-lepton unification at the TeV scale based on an $SU(4)$ gauge symmetry, while still having acceptable neutrino masses and enough suppression in flavor changing neutral currents. An approximate $U(2)$ flavor symmetry is an artifact of family-dependent gauge charges leading to a natural realization of the CKM mixing matrix. The model predicts sizeable violation of PMNS unitarity as well as a gauge vector leptoquark $U_1^{\mu }=(3,1,2/3)$ which can be produced at the LHC -- both effects within the reach of future measurements. In addition, recently reported experimental anomalies in semi-leptonic $B$-meson decays, both in charged $b\to c\tau \nu$ and neutral $b\to s\mu \mu$ currents, can be accommodated.

Comments: 9 pages, 5 tables. Version accepted for publication in PLB