Comment On ``Grand Unification and Supersymmetric Threshold"

Abstract

Barbieri and Hall have argued that threshold effects at the scale of grand-unification wipe out predictions on the SUSY scale, M_S. Using triviality arguments we give upper bounds on ultraheavy particles, while proton stability gives lower bounds on the mass of the higgs color-triplet. We find no useful lower bound on the $Σ$ supermultiplet, but if the strong coupling constant is as large as recent experiments suggest, unification in the minimal SUSY SU(5) model requires that the $Sigma$ masses be $\sim 10^{-7}M_V$ and that the color octet and weak triplet be split in mass by a factor of $\sim$100.