Abstract
The origin of neutrino masses remains one of the most pressing open questions in particle physics. While conventional approaches rely on extending the Standard Model with heavy fields or new symmetries, an alternative idea has recently emerged: neutrino masses may arise through refraction in the background of ultralight dark matter. In this framework, neutrinos acquire dynamic, effective, time-varying masses as they propagate through a coherent oscillating field, leading to distinctive imprints on oscillation experiments, beta-decay searches, and astrophysical neutrino signals. In this talk, I will introduce the basic mechanism of refractive neutrino masses and discuss its phenomenological consequences for laboratory, astrophysical, and cosmological probes and highlight how upcoming experiments may provide the first opportunities to test this novel connection between neutrinos and the dark sector.
