Can gravitational waves reveal axions hiding in flavor symmetries?

Axions solve the strong CP problem but need protection from quantum effects—gauged flavor symmetries provide that shield while explaining why electrons are 200,000 times lighter than top quarks. The model produces two smoking guns: rare particle decays and a distinctive gravitational wave signature from decaying cosmic strings. This GW spectrum pattern could be detected alongside flavor physics experiments, offering a new way to hunt high-quality axion dark matter.