Search for excited leptons with the DELPHI detector at LEP

A search for excited leptons with the DELPHI detector at LEP is reported. The data analysed correspond to an integrated luminosity of about 539 pb 1 collected at centre-of-mass energies ranging from 189 GeV to 208 GeV. The search for pairproduced excited leptons establishes 95% condence level mass limits in the region between 95 GeV/c 2 and 103 GeV/c 2 , depending on the channel. The search for singly produced excited leptons establishes upper limits on the ratio of the coupling of the excited lepton to its mass (=m ‘ ) as a function of the mass.