Search for charged lepton flavor violating Z and Z^' boson decays in proton-proton collisions at [Formula Presented]

A search for flavor violating decays of the Z boson to charged leptons is performed using data from proton-proton collisions at [Formula Presented] TeVcollected with the CMS detector at the LHC,corresponding to an integrated luminosity of 138 fb⁻¹. Each of the decays [Formula Presented] isconsidered. The data are consistent with the backgrounds expected from standard model processes. For the [Formula Presented] channel the observed (expected) 95% confidence level upper limit on the branching fraction is [Formula Presented], which is the most stringent direct limit to date on this process; the corresponding limits for the [Formula Presented] channels are [Formula Presented], respectively. Additionally, the eμ final state is used to search for lepton flavor violating decays of Z^' resonances in the mass range from 110 to 500 GeV. No significant excess is observed above the predicted background levels.