QCD axion from chiral gauge theories

Abstract

We present models of axion based on supersymmetric chiral gauge theories. In these models, the PQ symmetry is spontaneously broken by the non-perturbative dynamics of chiral gauge theory. Thanks to supersymmetry, IR dynamics of the models are calculable. We also present an example of a QCD axion model that is compatible with SU(5) grand unification. We find that in order to realize the gauge coupling unification with a certain precision, the GUT scale is the same with the PQ breaking scale, and the SUSY breaking scale is $\mathcal{O}(10^9)\mathrm{GeV}$.

Comments: 34 pages, 2 figures