Fourth-generation leptons at LEP2 Original Research Article

From non-observation at LEP1, a lower mass limit of 45 GeV has been established on any additional sequential fermion beyond three generations. Precision measurements have further constrained the number of such additional generations, either degenerate or nearly so, to be at most one. LEP2, an energy-upgraded version of LEPI, would provide a greater mass reach in the search for such particles. We study the pair production of fourth-generation leptons for various LEP2 energy options. We find that in most cases such particles could be discovered/ ruled out up to the kinematic limit.