A Predictive $SO(10)$ Model

TL;DR

This paper presents a non-supersymmetric $SO(10)$ grand unified model with testable predictions including proton decay, dark matter candidates, topological defects, gravitational waves, and baryon asymmetry, linking particle physics and cosmology.

Contribution

It introduces a novel $SO(10)$ model with a specific symmetry breaking pattern that unifies gauge couplings and connects inflation, dark matter, and observable proton decay predictions.

Findings

Proton decay may be observable at Hyper-Kamiokande.

The model predicts stable intermediate mass fermions and topological defects.

Gravitational wave background from strings is detectable in planned experiments.

Abstract

We discuss some testable predictions of a non-supersymmetric $SO(10)$ model supplemented by a Peccei-Quinn symmetry. We utilize a symmetry breaking pattern of $SO(10)$ that yields unification of the Standard Model gauge couplings, with the unification scale also linked to inflation driven by an $SO(10)$ singlet scalar field with a Coleman-Weinberg potential. Proton decay mediated by the superheavy gauge bosons may be observable at the proposed Hyper-Kamiokande experiment. Due to an unbroken $Z_2$ gauge symmetry from $SO(10)$, the model predicts the presence of a stable intermediate mass fermion which, together with the axion, provides the desired relic abundance of dark matter. The model also predicts the presence of intermediate scale topologically stable monopoles and strings that survive inflation. The monopoles may be present in the Universe at an observable level. We estimate the stochastic gravitational wave background emitted by the strings and show that it should be testable in a number of planned and proposed space and land based experiments. Finally, we show how the observed baryon asymmetry in the Universe is realized via non-thermal leptogenesis.