Grand gauge-Higgs unification and doublet-triplet splitting.

I present a new solution to the doublet-triplet splitting problem which works also in a SUSY SU(5) GUT and is testable at TeV-scale collider experiments. In this model, the SU(5) symmetry is broken through the Hosotani mechanism. Thanks to the phase nature of the Hosotani-breaking, the so-called "missing VEV" can be realized even in an SU(5) model to solve the problem. A general and distinctive prediction of this solution is the existence of light adjoint chiral supermultiplets with masses of the SUSY breaking scale which would be observed at the LHC. [ABSTRACT FROM AUTHOR]