$B-L$ as a Gauged Peccei-Quinn Symmetry

TL;DR

This paper explores embedding the Peccei-Quinn symmetry into a gauged B-L symmetry within a GUT framework, protecting the axion solution from quantum gravitational effects without extra singlet matter.

Contribution

It identifies B-L as a gauged Peccei-Quinn symmetry compatible with GUTs, avoiding additional singlet fields and addressing quantum gravity concerns.

Findings

B-L can serve as a gauged PQ symmetry in GUT models.

The model naturally incorporates right-handed neutrinos.

No extra singlet matter fields are needed for anomaly cancellation.

Abstract

The gauged Peccei-Quinn (PQ) mechanism provides a simple prescription to embed the global PQ symmetry into a gauged $U(1)$ symmetry. As it originates from the gauged PQ symmetry, the global PQ symmetry can be protected from explicit breaking by quantum gravitational effects once appropriate charge assignment is given. In this paper, we identify the gauged PQ symmetry with the ${B-L}$ symmetry, which is obviously attractive as the ${B-L}$ gauge symmetry is the most authentic extension of the Standard Model. As we will show, a natural $B-L$ charge assignment can be found in a model motivated by the seesaw mechanism in the $SU(5)$ Grand Unified Theory. As a notable feature of this model, it does not require extra $SU(5)$ singlet matter fields other than the right-handed neutrinos to cancel the self and the gravitational anomalies.