THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS
Abstract
A search for unstable heavy fermions with the DELPHI detector at LEP is reported. Sequential and non-canonical leptons, as well as excited leptons and quarks, are considered. The data analysed correspond to an integrated luminosity of about 48 pb(-1) at an e(+)e(-) centre-of-mass energy of 183 GeV and about 20 pb(-1) equally shared between the centre-of-mass energies of 172 GeV and 161 GeV. The search for pair-produced new leptons establishes 95% confidence level mass limits in the region between 70 GeV/c(2) and 90 GeV/c(2), depending on the channel. The search for singly produced excited leptons and quarks establishes upper limits on the ratio of the coupling of the excited fermion to its mass (lambda/mf(*)) as a function of the mass.
