Search for a nearly degenerate lepton doublet (L−,L0)

K. Riles, M. L. Perl, T. Barklow, A. Boyarski, P. R. Burchat, D. L. Burke, J. M. Dorfan, G. J. Feldman, L. Gladney, G. Hanson, K. Hayes, R. J. Hollebeek (+34 others)
1990 Physical Review D, Particles and fields  
We have searched for a heavy charged lepton with an associated neutrino of nearly the same mass in e e annihilation data taken with the Mark II detector at a center-of-mass energy of 29 GeV. In order to suppress contamination from conventional two-photon reactions, this analysis uses a novel, radiative-tagging technique. Requiring the presence of an isolated, energetic photon allows a search for lepton doublets with mass splittings smaller than that previously accessible to experiment. No
more » ... xperiment. No evidence for such a new lepton doublet has been found, enab1ing limits to be placed on allowed mass combinations. Mass splittings as low as 250-400 MeV/c are excluded for charged-lepton masses between 500 MeV/c' and 10 GeV/c .
doi:10.1103/physrevd.42.1 pmid:10012691 fatcat:2xrmutbdtfc23asn2iql5wzfhy