Phenomenology of superstring-inspired SO(10) grand-unified-theory model with intermediate scale.

Abstract

We examine in detail a superstring-inspired SO(10) grand-unified-theory model in which the mixing of Weinberg-Salam Higgs fields and large Majorana masses for right-handed neutrinos are generated by the higher-dimensional terms in the superpotential at the intermediate-scale symmetry breaking. Fixing the Higgs-field mixing strength $\ensuremath{\mu}$ as 1 TeV and assuming the usual soft terms of broken $N=1$ supergravity, we study the radiative symmetry breakings at the intermediate scale ${M}_{I}$ and the scale ${M}_{W}$. Conditions and constraints for the symmetry breakings severely restrict the allowed range of the supergravity parameters and give bounds on the top-quark mass ${m}_{t}$. We have obtained ${m}_{t}\ensuremath{\le}141$ GeV if the identity $B=A\ensuremath{-}1$ is assumed. The low-energy particle spectra are analyzed. All squarks and sleptons are predicted to have masses in the TeV region. Some of the gaugino-related supersymmetric particles can be light, and lower bounds for these sparticle masses are given. One neutral Higgs boson is light and the other Higgs bosons are all very massive (g a few TeV).