Non-renormalizable grand unification utilizing the leptoquark mechanism of neutrino mass

TL;DR

This paper explores a non-supersymmetric grand unified theory with scalar leptoquarks that relate neutrino masses to down-type quark masses, predicting specific particle masses and proton decay constraints.

Contribution

It introduces a non-renormalizable GUT model with scalar leptoquarks linking neutrino and quark masses, providing bounds on leptoquark and proton decay-related particle masses.

Findings

Color sextet, weak isodoublet at 1-10 TeV predicted.

Upper bound of 2.5 x 10^{15} GeV on scalar leptoquark masses.

Proton decay constraints imply leptoquark mass > 2.1 x 10^9 GeV.

Abstract

We analyze a non-supersymmetric, non-renormalizable grand unified theory whose particle content is that of the Georgi-Glashow model augmented only by scalars from the \textbf{10} and \textbf{35} representations. A prediction of our model is a color sextet, weak isodoublet whose mass lies at 1 TeV (10 TeV) and that does not couple to Standard Model fermions at tree level. The leptoquark mechanism through which Majorana neutrinos radiatively acquire their masses relates the neutrino mass matrix to that of the down-type quarks. A consequence of this relation and perturbativity of coupling constants is the upper bound of $2.5 \times 10^{15}$ GeV on the masses of the scalar leptoquarks $S_1^*$ and ${\widetilde R}_{2}$. Electroweak mixing of these leptoquarks induces a B-L violating decay of the proton which indirectly contrains the mass of ${\widetilde R}_{2}$ to be greater than $2.1 \times 10^9$ GeV. We find the grand unification scale to exceed $1.4 \times 10^{16}$ GeV in all scenarios considered.