Speaker
Description
Axions and axion-like particles (ALPs) remain compelling dark matter (DM) candidates, provided that the associated Peccei-Quinn (PQ) symmetry breaking scale is sufficiently large to ensure cosmological stability. In this talk, I will explore a novel framework in which ALPs possess flavor-violating (FV) couplings to Standard Model (SM) quarks, allowing them to be produced via freeze-in in the early universe. I will demonstrate that rare meson decays, such as $K \rightarrow \pi a \quad \text{and} \quad B \rightarrow K a,$ allow us to probe decay constants as high as $f_a \sim 10^{10{-}12}~\mathrm{GeV}.$ Remarkably, this parameter space is typically thought to be inaccessible to terrestrial experiments. The structure of FV couplings opens up opportunities to test otherwise elusive ALP scenarios, while remaining consistent with astrophysical and cosmological constraints. I will highlight key differences between the lepton and quark FV scenarios, particularly in their sensitivity to decay versus scattering production channels, the degree of suppression required to evade X-ray constraints, and the relevance of next-to-leading order (NLO) corrections. Altogether, this framework connects the flavor and dark matter frontiers, offering a new avenue to search for light dark matter candidates through precision flavor experiments and future X-ray telescopes.
