Search for Excited fermions

Results of searches for excited fermion production at LEP and HERA are presented. The data were collected with the DELPHI detector at LEP at e e centre-of-mass energies ranging from 189 GeV to 209 GeV, corresponding to an integrated luminosity of approximately 600 pb 1 , and with the H1 detector at HERA in e p collisions at a centre-of-mass energy of 300 GeV and in e p collisions at a centre-of-mass energy of 318 GeV, with integrated luminosities of 37 pb 1 and 15 pb 1 , respectively. In searches for pair-produced excited leptons, lower mass limits were established in the range 94 – 103 GeV/c 2 , depending on the channel and model assumptions. In searches for singly-produced excited fermions, upper limits on the parameter f Λ were set up to masses of the order of 250 GeV/c 2 . Inte