Nonrenormalizable SU(5) GUTs: Leptoquark-induced neutrino masses

We revisit the doublet–triplet splitting problem within the SU(5) gauge group framework to advocate a viable regime with the light scalar leptoquark of the doublet–triplet splitting notoriety that is compatible with the current experimental bounds on partial proton decay lifetimes. We explicitly demonstrate, through a consistent use of higher-dimensional operators, how to implement suppression of baryon number violating interactions of the aforementioned color triplet. Our study thus offers an alternative approach to the doublet-triplet splitting problem as it removes a need for an extreme mass hierarchy between the partners residing in the same representation. We furthermore pursue two different extensions of two distinct symmetry breaking scenarios of SU(5), one with a 24-dimensional representation and the other one with a 75-dimensional representation, to produce comparative study of novel consequences for the gauge coupling unification and the one-loop level neutrino mass generation. Our results point toward qualitatively novel SU(5) scenarios, where the light scalar leptoquarks, responsible for the neutrino mass generation, might be even accessible at colliders and thus serve as an accelerator accessible portal to the high-scale physics.