Search for excited leptons in e(+)e(-) collisions at root s=161 GeV

A search with the DELPHI detector at LEP for excited leptons (e*, mu*, tau* and nu*) decaying through gamma, W or Z transitions is reported. The data used correspond to an integrated luminosity of 10 pb(-1) e(+)e(-) centre-of-mass energy at an e of 161 GeV. The search for pair produced excited leptons established the limits m(e)* > 79.6 GeV/c(2), m(mu)* > 79.6 GeV/c(2), m(tau)* 79.4 GeV/c(2) and m(nu)* > 56.4 GeV/c(2) at 95% confidence level, assuming that the SU(2) and U(I) couplings of excited leptons are in the same ratio as for normal leptons and considering both left and right-handed components. Limits corresponding to other assumptions are also given. The search for single excited lepton production established upper limits on the ratio lambda/m(l)* of the coupling of the excited lepton to its mass.