Lepton flavor violating $Z\to l_il_j$ in flavor-universal   topcolor-assisted technicolor
  In the context of flavor-universal topcolor-assisted technicolor (TC2) models, we calculate the lepton flavor violating (LFV) $Z\to l_il_j$ decays. We find that the extra U(1) gauge boson $Z^{\prime}$ can give significant contributions to these LFV processes. With reasonable values of the parameters, the branching ratios of the processes $Z\to \tau\mu$ and $Z\to \tau e$ can approach the experimental upper limits. The indirect bound on the process $Z\to \mu e$ can give a severe constraint on the flavor-universal TC2 models. 
Chongxing Yue, Hong Li, Yanming Zhang, Yong Jia