Electroweak limits on nonuniversal $Z^{\prime }$ bosons

Many types of physics beyond the standard model include an extended electroweak gauge group. If these extensions are associated with flavor symmetry breaking, the gauge interactions will not be flavor universal. In this paper we update the bounds placed by electroweak data on the existence of flavor nonuniversal extensions to the standard model in the context of top-color assisted technicolor (TC2), noncommuting extended technicolor (NCETC), and the ununified standard model (UUM). In the first two cases the extended gauge interactions couple to the third generation fermions differently than to the light fermions, while in the ununified standard model the gauge interactions couple differently to quarks and leptons. The extra $\mathrm{SU}\left(2\right)\mathrm{}$ triplet of gauge bosons in NCETC and UUM models must be heavier than about 3 TeV, while the extra Z boson in TC2 models must be heavier than about 1 TeV.