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

Understand

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.