Structure and prospects of the simplest SO(10) GUTs

TL;DR

This paper reviews minimal SO(10) grand unified theories with adjoint Higgs, highlighting that relaxing traditional assumptions reveals lighter intermediate states, which can impact TeV-scale phenomenology and proton decay predictions.

Contribution

It demonstrates that the minimal survival approximation underestimates the B-L scale, allowing for a broader parameter space compatible with non-supersymmetric unification and the seesaw mechanism.

Findings

B-L scale estimates can be relaxed by up to four orders of magnitude.

Intermediate-scale states may be as light as TeV, affecting collider phenomenology.

Proton decay predictions in minimal SO(10) models are potentially more accessible.

Abstract

We recapitulate the latest results on the class of the simplest SO(10) grand unified models in which the GUT-scale symmetry breaking is triggered by an adjoint Higgs representation. We argue that the minimal survival approximation traditionally used in the GUT- and seesaw-scale estimates tends to be blind to very interesting parts of the parameter space in which some of the intermediate-scale states necessary for non-supersymmetric unification of the SM gauge couplings can be as light as to leave their imprints in the TeV domain. The stringent minimal-survival-based estimates of the B-L scale are shown to be relaxed by as much as four orders of magnitude, thus admitting for a consistent implementation of the standard seesaw mechanism even without excessive fine-tuning implied by the previous studies. The prospects of the minimal renormalizable SO(10) GUT as a potential candidate for a well-calculable theory of proton decay are discussed in brief.