New Topflavor Models with Seesaw Mechanism

Abstract

New class of models are constructed in which the third family quarks, but not leptons, experience a new SU(2) or U(1) gauge force. Anomaly cancellation enforces the introduction of spectator quarks so that the top and bottom masses are naturally generated via a seesaw mechanism. We find the new contributions to the (S,T,U) parameters and Zbb vertex to be generically small. We further analyze how the reasonable flavor mixing pattern can be generated to ensure the top-seesaw mechanism and sufficiently suppress the flavor-changing effects for light quarks. Collider signatures for the light Higgs boson and top quark are also discussed.

To match the version in Rapid Communication of PRD, RevTex 5pp