Search for excited leptons at 130–140 GeV

Abstract

A search for the radiative decay of excited charged leptons, ℓ ∗, and for radiative and weak decays of excited electron neutrinos, ν e ∗ , is performed, using the 5.8 pb −1 of data collected by ALEPH at 130–140 GeV. No evidence for a signal is found in single or pair production. Excluded mass limits from pair production are close to 65 GeV/ c 2 for all excited lepton species. Limits on the couplings, λ m ℓ ∗ , of excited leptons are derived from single production. For an excited lepton mass of 130 GeV/ c 2, these limits are 0.04 GeV −1 for μ ∗ and τ ∗ , and 0.0007 GeV −1 for e ∗. For ν e ∗ , the limit is at the level of 0.03 GeV −1 for a mass of 120 GeV/ c 2, independent of the decay branching ratios.