Hints of Dynamical Symmetry Breaking?

Abstract

There is current interest in a possible new massive gauge boson $X$ which mixes slightly with the $Z$ boson and accounts for certain anomalies in the LEP data. We show why constraints on models in which the $X$ boson does not couple to the first two families suggest dynamical electroweak symmetry breaking. The associated TeV mass fermions make up a fourth family. Constraints on the effects of the fourth left-handed neutrino also suggest a dynamical origin for its Majorana mass. We finally comment on related implications for the origin of quark masses.