Ultralight Particles Across the Spectra

Masha Baryakhtar (University of Washington)

Title: Ultralight Particles Across the Spectra

Abstract: Theories that seek to explain the outstanding puzzles of the Standard Model of particle physics often predict light, feebly-interacting particles whose discovery requires novel search strategies. Perhaps the most motivated is the QCD axion, which can elegantly solve the outstanding strong-CP problem of the Standard Model; other ultralight bosons may also appear in these theories and in our universe.  I will discuss a range of search strategies for these elusive particles. First, I will present my experimental proposal based on dielectric metamaterials, in which axion dark matter can efficiently convert to detectable single photons. Second, I will turn to the early universe, where even a small trace of ultralight scalar fields can be observed through the power of the cosmic microwave background. Finally, I will discuss how rotating black holes source exponentially large numbers of gravitationally-bound bosons, creating nature's laboratories for ultralight particles. In the case of dark photons, the resulting system appears as a novel multimessenger source in the sky.