Speaker
Description
The flavor symmetry-breaking scale in the Froggatt-Nielsen (FN) mechanism is very weakly constrained by present experiments and can lie anywhere between a few TeVs and the Planck scale. We construct two minimal, non-supersymmetric, ultraviolet (UV) complete models that generate the FN mechanism, with a global $U(1)_{\rm{FN}}$ flavor symmetry and a single flavon field. Using the one-loop finite temperature effective potential, we explore the possibility of a strong first-order phase transition (SFOPT) induced by the flavon. We show that if the flavor symmetry-breaking occurs at intermediate scales $\sim 10^4-10^7$ GeV, then in certain regions of the parameter space, the associated stochastic gravitational wave (GW) background is strong enough to be detected by planned GW observatories. We identify viable parameter regions for the best detection prospects. A strong GW signal prefers $\mathcal{O}(1)$ values of the quartic coupling for Higgs-flavon mixing, $\lambda_{HS}$, and $\mathcal{O}(0.1)$ values of the flavon quartic coupling, $\lambda_S$. We show that the observed parameter space is compatible with Higgs data. While both models of flavor can produce a detectable GW background, the GW signature does not discriminate between them.
