Dark Matter Stability from residual flavour symmetries

We propose a model-independent framework in which Dark Matter stability emerges naturally from residual discrete ${\mathbb{Z}}_N$ symmetries left unbroken by the spontaneous breaking of continuous flavour symmetries, both Abelian and non-Abelian. No ad hoc stabilizing symmetry is required, as Dark Matter stability is an inherent consequence of the underlying flavour dynamics. As an explicit example, we construct a prototype model based on a $\text{SU}(2{)}_{\text{F}}\otimes \text{U}(1{)}_{\text{F}}$ Froggatt-Nielsen symmetry, which successfully reproduces the observed charged lepton mass spectrum and the PMNS mixing matrix, while identifying the lightest sterile neutrino as a stable Dark Matter candidate. Furthermore, we study the Dark Matter phenomenology within our model in the freeze-in regime, including production channels mediated by higher-dimensional operators suppressed by the cutoff scale $\mathrm{\Lambda }$. Our analysis shows that continuous flavour symmetries can provide a unified, self-consistent framework addressing both the flavour puzzle and the origin, stability, and production of Dark Matter.