We explore the phenomenological structure of a string-theory-inspired ${\mathrm{E}}_6$ grand unified group with low-energy gauge group SU(2${)}_{\mathrm{L}}$×U(1${)}_{\mathrm{Y}}$×U(1${)}_{\mathrm{Y}\mathcal{’}}$, with emphasis upon its implications for Higgs-boson production and detection. We first summarize constraints on the theory deriving from known limits on Z-Z’ mixing. We then describe how the most general superpotential allowed by ${\mathrm{E}}_6$ leads to constraints upon and relations among the various Higgs-boson masses, and between the Higgs-boson spectrum, the Z’, and the masses of supersymmetric particles. In addition we explore the couplings of the Higgs boson to the gauge and other particles of the theory and emphasize the associated implications for Higgs-boson and supersymmetric-particle detection. The tightly constrained nature of the parameter space of the theory leads to very specific predictions.

• Received 21 January 1988

DOI:https://doi.org/10.1103/PhysRevD.38.105