Speaker
Description
$SU(5)$ grand unified model, which unifies SM quarks and leptons in $\overline{5}$ and $10$ dimensional irreducible representations, yields observationally inconsistent tree-level Yukawa relations when only a single $5_{\rm H}$ or $45_{\rm H}$ dimensional irrep having a single Higgs contributes to the Yukawa sector. For instance, only $5_{\rm H}$ dimensional Higgs in the Yukawa sector yields $Y_d = Y_e^T$, while $45_{\rm H}$ gives $3Y_d = Y_e^T$. These inconsistent tree-level Yukawa relations can be rendered viable by switching on one-loop corrections to different Yukawa vertices. The former scenario requires extending the minimal model by $SU(5)$ singlets while the latter one requires splitting of mass of scalars residing in the same multiplet. Other setups are also explored where radiative effects make the inconsistent tree-level frameworks viable. As an application, a realistic, viable $SU(5)\times Z_3$ framework is constructed explaining neutrino-less double beta decay and adhering to proton decay constraints. Importantly, the findings highlight the feasibility of the simplest Yukawa sector when accounting for quantum corrections and substantial threshold effects.
The talk is based on the following references:
-- Phys.Rev.D 109 (2024)
-- 2411.06906 [hep-ph]
-- JHEP 01 (2026) 061
