Leptoquarks with Exactly Stable Protons

Abstract

We explore a novel mechanism to restrict TeV-scale leptoquark interactions and render the proton exactly stable to all orders in the effective field theory expansion. A scalar condensate breaks a lepton-flavoured $\mathrm{U}(1{)}_X$ gauge symmetry in the ultraviolet and generates neutrino masses, leaving a discrete ${\mathbb{Z}}_9$ or ${\mathbb{Z}}_{18}$ gauge symmetry in the infrared, forbidding $\Delta B=1$ processes. This provides an elegant framework to address the flavour anomalies and can be adapted to many other new-physics models. The $\mathrm{U}(1{)}_X$ can emerge from a gauge-flavour unified $\mathrm{SU}(12)\times \mathrm{SU}(2)\times \mathrm{SU}(2)$ theory at even higher energies.

Comments: 9 pages, 1 figure, 2 tables. v2: published version