Dark Matter and Gauge Coupling Unification in Non-supersymmetric SO(10) Grand Unified Models

TL;DR

This paper explores how non-supersymmetric SO(10) grand unified models can achieve gauge coupling unification and naturally incorporate a stable dark matter candidate, identifying only two viable models under various phenomenological constraints.

Contribution

It systematically analyzes intermediate gauge groups in SO(10) models for dark matter stability and unification, revealing only two models compatible with phenomenological constraints.

Findings

Only two models satisfy all phenomenological constraints.

Dark matter stability is guaranteed by a leftover Z2 symmetry.

Unification achieved at two-loop level with specific intermediate gauge groups.

Abstract

Unlike minimal SU(5), SO(10) provides a straightforward path towards gauge coupling unification by modifying the renormalization group evolution of the gauge couplings above some intermediate scale which may also be related to the seesaw mechanism for neutrino masses. Unification can be achieved for several different choices of the intermediate gauge group below the SO(10) breaking scale. In this work, we consider in detail the possibility that SO(10) unification may also provide a natural dark matter candidate, stability being guaranteed by a leftover $Z_2$ symmetry. We systematically examine the possible intermediate gauge groups which allow a non-degenerate, fermionic, Standard Model singlet dark matter candidate while at the same time respecting gauge coupling unification. Our analysis is done at the two-loop level. Surprisingly, despite the richness of SO(10), we find that only two models survive the analysis of phenomenological constraints, which include suitable neutrino masses, proton decay, and reheating.