IsZ2Kuseful for labeling fermion generations?

Abstract

The cyclic group ${Z}_{2K}$, which survives after the breakdown of $\mathrm{U}{(1)}_{X}$ through the instanton effects in composite models of massless quarks and leptons, is phenomenologically considered to label the fermion generations. In a simple case, where the usual SU(5) fermion multiplets are labeled by ${Z}_{6}$, the Georgi-Jarlskog mass matrices are shown to be obtained. The $t$-quark mass is also conjectured to be \ensuremath{\sim} 30 GeV.