Experimental mass limit for the fourth-generation sequential lepton from e/sup +/e/sup -/ annihilations at. sqrt. s-bar = 56 GeV

A search for pair production for fourth-generation sequential leptons in e/sup +/e/sup -/ annihilation at a center-of-mass energy ..sqrt..s = 56 GeV is reported. Event topologies corresponding to the cases where one particle decays leptonically while the other decays hadronically as well as those where both particles decay hadronically were explored. We set a 95%-confidence-level lower limit of 27.6 GeV/c/sup 2/ for the mass of a fourth-generation lepton.