Minimal axion model from flavor

We show that solving the flavor problem of the Standard Model with a simple U(1)H flavor symmetry naturally leads to an axion that solves the strong $CP$ problem and constitutes a viable Dark Matter candidate. In this framework, the ratio of the axion mass and its coupling to photons is related to the SM fermion masses and predicted within a small range, as a direct result of the observed hierarchies in quark and charged lepton masses. The same hierarchies determine the axion couplings to fermions, making the framework very predictive and experimentally testable by future axion and precision flavor experiments.