Fits to SO(10) Grand Unified Models

TL;DR

This paper performs detailed numerical fits of SO(10) grand unified models at the weak scale, incorporating recent experimental data and RG evolution, to analyze neutrino properties, Higgs mass, and Yukawa couplings in both SUSY and non-SUSY contexts.

Contribution

It introduces a comprehensive fitting procedure at the weak scale for SO(10) GUT models, including RG evolution and recent experimental constraints, which is novel compared to previous high-scale fits.

Findings

Fits are sensitive to the top-quark mass and Higgs mass.

Predictions for neutrino masses and mixing parameters are provided.

Inclusion of recent neutrino and Higgs data constrains model parameters.

Abstract

We perform numerical fits of Grand Unified Models based on SO(10), using various combinations of 10-, 120- and 126-dimensional Higgs representations. Both the supersymmetric and non-supersymmetric versions are fitted, as well as both possible neutrino mass orderings. In contrast to most previous works, we perform the fits at the weak scale, i.e. we use RG evolution from the GUT scale, at which the GUT-relations between the various Yukawa coupling matrices hold, down to the weak scale. In addition, the right-handed neutrinos of the seesaw mechanism are integrated out one by one in the RG running. Other new features are the inclusion of recent results on the reactor neutrino mixing angle and the Higgs mass (in the non-SUSY case). As expected from vacuum stability considerations, the low Higgs mass and the large top-quark Yukawa coupling cause some pressure on the fits. A lower top-quark mass, as sometimes argued to be the result of a more consistent extraction from experimental results, can relieve this pressure and improve the fits. We give predictions for neutrino masses, including the effective one for neutrinoless double beta decay, as well as the atmospheric neutrino mixing angle and the leptonic CP phase for neutrino oscillations.