Leptoquarks with exactly stable protons

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-flavored U(1) X gauge symmetry in the ultraviolet and generates neutrino masses, leaving a discrete Z 9 or Z 18 gauge symmetry in the infrared, forbidding ∆ B = 1 processes. This provides an elegant framework to address the flavour anomalies and can be adapted to many other new-physics models. The U(1) X can emerge from a gauge–flavour unified SU(12) × SU(2) × SU(2) theory at even higher energies.