Non-universal gauge bosons $Z^{\prime }$ and rare top decays

Abstract

We study a new method for detecting non-universal gauge bosons $Z^{\prime }$ via considering their effects on rare top decays. We calculate the contributions of the non-universal gauge bosons $Z^{\prime }$ predicted by topcolor-assisted technicolor (TC2) models and flavor-universal TC2 models on the rare top decays $t⟶cV(V=g,\gamma ,Z)$ and $t⟶c{l}_i{l}_j(l_i,l_j=\tau ,\mu$, 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 $Br(t⟶cg)\sim 10^{-5}$ and $Br(t⟶c\tau \tau )\sim 10^{-7}$, which may approach the observable threshold of near future experiments. Non-universal gauge bosons $Z^{\prime }$ may be detected via the rare top decay processes at the top-quark factories such as the CERN LHC.

references added