High-quality Peccei-Quinn symmetry from the interplay of vertical and horizontal gauge symmetries

Luca Di Luzio, Giacomo Landini, Federico Mescia +1

We explore a class of axion models where an accidental $\mathrm{U}(1)$ Peccei-Quinn (PQ) symmetry automatically emerges from the interplay of vertical (grand-unified) and horizonta…