Finite Naturalness and Quark-Lepton Unification

TL;DR

This paper investigates the implications of finite naturalness in Pati-Salam models with quark-lepton unification, analyzing radiative corrections to the Higgs mass and their impact on model viability.

Contribution

It provides a detailed analysis of radiative corrections in minimal quark-lepton unification models, highlighting the dominance of two-loop corrections and proposing ways to relax naturalness bounds.

Findings

Radiative corrections to the Higgs mass are large, at least 10^4 times the Higgs mass squared.

Two-loop corrections for vector leptoquarks cancel at leading order.

Two-loop corrections dominate the finite naturalness bound, but can be mitigated.

Abstract

We study the implications of finite naturalness in Pati-Salam models where $SU(3)_C$ is embedded in $SU(4)$. For the minimal realization at low-scale of quark-lepton unification, which employs the inverse seesaw for neutrino masses, we find that radiative corrections to the Higgs boson mass are at least $\delta m_h^2 / m_h^2 \sim {\cal O}(10^4)$. The one-loop contributions to the Higgs mass are suppressed by four powers of the hypercharge gauge coupling. We find that for the vector leptoquarks the naively leading part of the two-loop corrections cancel. We assume the Dirac Yukawa couplings for neutrinos are equal to the up-type quark Yukawa couplings as predicted in the minimal theory for quark-lepton unification. Despite these findings, the two-loop corrections still dominate the finite naturalness bound. We mention a way to relax the lower bound on the vector leptoquark mass and have $\delta m_h^2 / m_h^2 \sim {\cal O}(10^2)$.