Quarks, Triality, and Unitary Symmetry Schemes

It is shown that integral eigenvalues of $\frac{Q}{e}$ can be achieved for Gell-Mann's quarks (particles belonging to representations of S${\mathrm{U}}_3$ with nonzero triality type) by the introduction of a new additive quantum number for strongly interacting particles and a corresponding alteration of the Gell-Mann-Nishijima formula. A possible framework wherein such ideas can be formulated is provided by an extension of S${\mathrm{U}}_3$ symmetry to S${\mathrm{U}}_4$ or perhaps a higher unitary symmetry.