An investigation into the lepton flavor changing neutral current at a Z-factory

The potential for detecting the lepton flavor changing neutral current (LFCNC) via the Z → eτ rare decay at a Z -factory is investigated. Practicable event selection strategies are designed to increase signal significance over SM contributions. Assuming no apparent deviation from SM predictions, one can conclude that the most general model-independent LFCNC effective form factors would be constrained at an unprecedent level, and accordingly a 3-order improvement from LEP1 measurements on the upper limit of BR( Z → eτ ) could be achieved, as precisely as 10 −8 with 100 fb −1 at Z -factory.