SU(5) Theories with Both Proton Stability and Cosmological Baryon-Number Generation

It is shown how the addition of a global $\mathrm{U}{\mathrm{}\left(1\right)\mathrm{}}_c$ of color to the conventional SU(5) model leads to a stable proton despite the nonconservation of baryon number. A stable, massive, neutral lepton is also predicted. The possibility that emerges of having relatively light mass ($M\gtrsim M_W$) color-triplet Higgs mesons modifies the gauge hierarchy problem and leads to cosmological baryon-number generation at low temperatures ($\mathrm{kT}\approx 100$ GeV).