Non-universal gauge bosons Z ′ and rare top decays

Abstract

We study a new method for detecting non-universal gauge bosons Z ′ via considering their effects on rare top decays. We calculate the contributions of the nonuniversal gauge bosons Z ′ predicted by topcolor-assisted technicolor (TC2) models and flavor-universal TC2 models on the rare top decays t − → cV (V = g,γ,Z) and t − → clilj(li,lj = τ,µ, or e). We show that the branching ratios of these processes can be significantly enhanced. Over a sizable region of the parameter space, we have Br(t − → cg) ∼ 10 −5 and Br(t − → cττ) ∼ 10 −7, which may approach the observable threshold of near future experiments. Non-universal gauge bosons Z ′ may be detected via the rare top decay processes at the top-quark factories such as the CERN LHC. PACS number(s): 14.70.Pw, 12.60.Cn, 14.65.Ha