Coupling Unification and Dark Matter in a Standard Model Extension with Adjoint Majorana Fermions

TL;DR

This paper explores an extension of the Standard Model with Majorana fermions in adjoint representations, achieving coupling unification and a viable dark matter candidate, with testable proton decay predictions.

Contribution

It demonstrates that adjoint Majorana fermions can unify couplings and provide a dark matter candidate, linking unification with dark matter in a novel way.

Findings

Successful coupling unification with adjoint fermions.

The $SU(2)_L$ triplet fermion as a dark matter candidate.

Predicted short proton lifetime testable by future experiments.

Abstract

We revisit an extension of the Standard Model with Majorana fermions in the adjoint representations. There, a precise coupling unification and the good candidate for dark matter (the $SU(2)_L$ triplet fermion) are achieved simultaneously. In particular, we show that the $SU(3)_c$ octet fermion which is required for successful unification can be a good non-thermal source of the triplet fermion dark matter. We also show that the scenario predicts a rather short lifetime of the proton compared with the supersymmetric Standard Model, and the most parameter space can be explored by the future experiments such as the Hyper-Kamiokande experiment.