Neutrino Mass, Coupling Unification, Verifiable Proton Decay, Vacuum Stability and WIMP Dark Matter in SU(5)

TL;DR

This paper proposes an extended non-supersymmetric SU(5) model that achieves gauge coupling unification, explains neutrino masses via type-II seesaw, predicts verifiable proton decay, and accommodates WIMP dark matter, addressing several Standard Model shortcomings.

Contribution

The authors extend the minimal SU(5) model with additional Higgs representations to unify gauge couplings, generate neutrino masses, and include a viable dark matter candidate, all while predicting observable proton decay.

Findings

Achieves precision gauge coupling unification without light non-standard particles.

Provides a lower bound on triplet mass for neutrino mass generation.

Predicts proton lifetime within reach of current and future experiments.

Abstract

Nonsupersymmetric minimal SU(5) with Higgs representations ${24}_H$ and $5_H$ and standard fermions in ${\bar 5}_F\oplus {10}_F$ is well known for its failure in unification of gauge couplings and lack of predicting neutrino masses. Like standard model, it is also affected by the instability of the Higgs scalar potential. We note that extending the Higgs sector by ${75}_H$ and ${15}_H$ not only leads to the popular type-II seesaw ansatz for neutrino masses with a lower bound on the triplet mass $M_{\Delta} > 2\times 10^9$ GeV, but also achieves precision unification of gauge couplings without proliferation of non-standard light Higgs scalars or fermions near the TeV scale. Consistent with recent LUX-2016 lower bound, the model easily accommodates a singlet scalar WIMP dark matter near the TeV scale which resolves the vacuum stability issue even after inclusion of heavy triplet threshold effect. We estimate proton lifetime predictions for $p\to e^+\pi^0$ including uncertainties due to input parameters and threshold effects due to superheavy Higgs scalars and superheavy $X^{\pm 4/3},Y^{\pm 1/3}$ gauge bosons. The predicted lifetime is noted to be verifiable at Super Kamiokande and Hyper Kamiokande experiments.