Accidental Approximate Generation Universality and its Possible Verification

Abstract

The universality of $e-\mu-\tau$ interactions may only be an accidental approximate symmetry analogous to that of flavor SU(2) and SU(3). This was specifically realized by an extension of the standard model proposed in 1981. Two key predictions are that the $\tau$ lifetime should be longer and that the $\rho$ parameter measured at the Z peak should have an additional negative contribution. These are consistent with present precision electroweak measurements. A future decisive test of this model would be the discovery of new W and Z bosons with nearly degenerate masses of a few TeV.