Search for excited leptons in e+e− annihilation at s = 130-140 GeV

Abstract We report on a search for the excited leptons e ∗ , μ ∗ , τ ∗ and ν ∗ in e + e − collisions at s = 130-140 GeV using the L3 detector at LEP. No evidence has been found for their existence. From an analysis of the expected pair produced l ∗ l ∗ in the channels eeγγ, μμγγ, ττγγ, eeWW, and ννγγ, we determine the lower mass limits at 95% C.L. of 64.7 GeV for e ∗ , 64.9 GeV for μ ∗ , 64.2 GeV for τ ∗ , 57.3 GeV (eW decay mode) and 61.4 GeV (νγ decay mode) for ν ∗ . From an analysis of the expected singly produced ll ∗ in the channels eeγ, μμγ, ττγ, νeW and ννγ, we determine upper limits on the couplings λ m l ∗ up to m l ∗ = 130 GeV .