Leptoquarks, axions and the unification of B, L, and Peccei-Quinn symmetries

TL;DR

This paper explores models unifying axion, baryon, and lepton symmetries using leptoquarks and diquarks, analyzing B and L violation patterns and their implications for nucleon decay, neutron oscillations, and cosmology.

Contribution

It introduces a framework linking axion models with baryon and lepton number violations through leptoquarks and diquarks, unifying these symmetries and exploring their phenomenological consequences.

Findings

Unified symmetry framework involving axions, B, and L.

Possible nucleon decay channels involving axions.

Implications for neutron-antineutron oscillations and cosmology.

Abstract

In this paper, axion models supplemented by leptoquarks and diquarks are systematically analyzed. Turning on some couplings to and among these latter states permits to unify the Peccei-Quinn symmetry with baryon (B) and lepton (L) numbers, such that the axion becomes associated to the spontaneous breaking of the three $U(1)$ symmetries. All possible four- and six-fermion patterns of B and L violation are discussed, including those inducing proton decay, with $\Delta B = 1$ and $\Delta L = \pm 1, \pm 3$, neutron-antineutron oscillations with $\Delta B = 2$, and Majorana neutrino masses with $\Delta L = 2$. Scenarios in which one or two axion fields necessarily appear in any B and/or L violating operators are also constructed. Nucleon decays would then necessarily involve an axion in the final state, while neutron-antineutron oscillations would only happen in an axionic background. This could have implications for the neutron lifetime puzzle, and more generally, opens the door to new phenomenological and cosmological applications.