Effective Lagrangian description of the lepton flavor violating decays Z-->li lj

A comprehensive analysis of the lepton flavor violating (LFV) decays Z–>li lj is presented within the effective Lagrangian approach. Both the decoupling and nondecoupling scenarios are explored. The experimental constraints from li –> lj lk \bar{lk} and li -->lj gamma as well as some relationships arising from the gauge invariance of the effective Lagrangian are used to put constraints on Z–>li lj. It is found that while current experimental data impose very strong constraints on Z–>mu e, the channel Z --> tau mu (e)still may be at the reach of the planned TESLA collider.