Grand gauge-Higgs unification

Abstract

We propose a novel way to break grand unified gauge symmetries via the Hosotani mechanism in models that can accommodate chiral fermions. Adjoint scalar fields are realized through the so-called diagonal embedding method which is often used in the heterotic string theory. We calculate the one-loop effective potential of the adjoint scalar field in a five dimensional model compactified on an ${S}^{1}/{\mathbb{Z}}_{2}$ orbifold, as an illustration. It turns out that the potential is basically the same as the one in an ${S}^{1}$ model, and thus the results in literatures, in addition to the chiral fermions, can be realized easily.