Vacuum Instability and New Constraints on Fermion Masses

I show that, in the Weinberg-Salam model with one Higgs doublet, in order for the physical vacuum to be an absolute minimum (in the one-loop approximation), certain requirements on the fermion masses have to be met. Specifically, the quantity {{i^{m₅₈}^4}}^1{4}, where the summation extends over fermions, is bounded from above by approximately 133. 5 GeV ({sin^2}ₖ=0. 25) or 137. 7 GeV ({sin^2}ₖ=0. 2).