On axion and familons

Abstract

We study the connection between the global family symmetry G F=SU( N) and Peccei-Quinn symmetry U(1) PQ in the context of SO(10). It turns out that GF automatically leads to U(1) PQ, if the Higgs representation is properly restricted. This implies that the decay K + → π + + nothing (Goldstone boson) should be observable soon. Furthermore, for odd number of families, the theory is free from the axionic domain wall problem. Finally, if B— L breaking is tied to G F and U(1) PQ breaking, the theory favors three families of fermions.