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 =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.

Gauge symmetry breaking patterns in an SU(5) grand gauge-Higgs unification model

“…As studied in the paper [6], the Kaluza-Klein (KK) mass spectrum for the Ψ (±) with η 6) and that for the Ψ (±) with η 0 Ψ η π Ψ = −1 by the same form in Eq. (2.6) with replacement n → n + 1/2, which implies that the KK mass spectrum is basically the same form with the one obtained for the S 1 compactification.…”

“…In addition, if a specific vacuum which is realized as a local minimum in Ref. [6] is assumed, the so-called doublet-triplet splitting problem can be naturally solved [10].…”

The standard model gauge symmetry from higher-rank unified groups in grand gauge-Higgs unification models

“…This situation leads to severe constraints on construction of gGHU models. We have shown that the difficulty is evaded and the adjoint "Higgs" field in the gGHU model is obtained [54,55] with the diagonal embedding method [63][64][65][66][67][68][69][70], which is known in the context of string theory. The doublettriplet splitting problem and several phenomenological aspects have been studied in the supersymmetric version of the model [56,57].…”

“…Recently, we have been focusing on application of the Hosotani mechanism to unified gauge symmetry breaking on an orbifold compactification S 1 /Z 2 , which enable us to incorporate chiral fermions in five-dimensional models [54][55][56][57]. In this case, the zero mode of the extra-dimensional gauge field, which have even parities under a boundary condition defined at the boundaries of the orbifold, plays a role of the Higgs field whose VEV breaks unified gauge symmetries into the standard model one.…”

Μ Parameter From Dynamical Rearrangement of U(1) and Θ Parameter

“…The other is that we use a variant of the diagonal embedding proposed in Ref. [21]. As shown later, we can impose appropriate BCs on both SM gauge bosons and matter fields, and the non-abelian structure such as SU(2) can be build by making a difference between the eigenstates of U(1) gauge symmetry and those of BCs.…”