Higgs-boson mass bound inE6-based supersymmetric theories

We consider low-energy supersymmetric models which come from ${\mathrm{E}}_6$-based grand unified or superstring-inspired theories whose scalar fields come from 27’s, 27¯’s, or 1’s of ${\mathrm{E}}_6$. Two classes of models emerge. In one, an upper bound of 108 GeV to the mass of the lightest Higgs scalar is found, independent of the precise gauge group, soft-supersymmetry-breaking parameters, or superpotential parameters. In the other, the requirement of perturbative unification is sufficient to arrive at a similar bound. Other Higgs-boson mass relations are also discussed. Failure to find a Higgs boson with a mass near or below 108 GeV would therefore rule out nearly all such ${\mathrm{E}}_6$-based models.