We explore a Z boson with family-nonuniversal couplings to charged leptons. The general effect of Z-Z mixing, of both kinetic and mass types, is included in the analysis. Adopting a model-independent approach, we perform a comprehensive study of constraints on the leptonic Z couplings from currently available experimental data on a number of flavor-conserving and flavor-changing transitions. Detailed comparisons are made to extract the most stringent bounds on the leptonic couplings. Such information is fed into predictions of various processes that may be experimentally probed in the near future.
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