Quark-lepton Yukawa ratios and nucleon decay in SU(5) GUTs with type-III seesaw

Abstract

We consider an extension of the Georgi-Glashow SU(5) GUT model by a 45-dimensional scalar and a 24-dimensional fermionic representation, where the latter leads to the generation of the observed light neutrino masses via a combination of a type I and a type III seesaw mechanism. Within this scenario, we investigate the viability of predictions for the ratios between the charged lepton and down-type quark Yukawa couplings, focusing on the second and third family. Such predictions can emerge when the relevant entries of the Yukawa matrices are generated from single joint GUT operators (i.e. under the condition of single operator dominance). We show that three combinations are viable, (i) $y_{\tau }/y_b=3/2$, $y_{\mu }/y_s=9/2$, (ii) $y_{\tau }/y_b=2$, $y_{\mu }/y_s=9/2$, and (iii) $y_{\tau }/y_b=2$, $y_{\mu }/y_s=6$. We extend these possibilities to three toy models, accounting also for the first family masses, and calculate their predictions for various nucleon decay rates. We also analyse how the requirement of gauge coupling unification constrains the masses of potentially light relic states testable at colliders.

12 pages + 2 appendices + references, 4 figures

References in corpus (17)

• The Leptoquark Hunter's Guide: Pair Production
• Probing seesaw at LHC
• Search for heavy charged long-lived particles in the ATLAS detector in 36.1 fb${}^{-1}$ of proton-proton collision data at $\sqrt{s}=13$ TeV
• Renormalizable Adjoint SU(5)
• New GUT predictions for quark and lepton mass ratios confronted with phenomenology
• Upper Bound on the Mass of the Type III Seesaw Triplet in an SU(5) Model
• Naturalness of the Non-Universal MSSM in the light of the recent Higgs results
• θ^PMNS_13 = θ_C / \sqrt2 from GUTs
• Fermion Masses and the UV Cutoff of the Minimal Realistic SU(5)
• Unification versus proton decay in SU(5)
• Search for nucleon decay into charged antilepton plus meson in 0.316 megaton$\cdot$years exposure of the Super-Kamiokande water Cherenkov detector
• Towards predictive flavour models in SUSY SU(5) GUTs with doublet-triplet splitting
• On the Origin of Two-Loop Neutrino Mass from SU(5) Grand Unification
• Towards Minimal SU(5)
• A Parameter Space Exploration of the Minimal SU(5) Unification
• From Flavour to SUSY Flavour Models
• Predictions from a flavour GUT model combined with a SUSY breaking sector