Department of Physics

Abstract: The QCD axion is a hypothetical particle proposed to solve the strong CP problem and thus explain why neutrons have a vanishing electric dipole moment. The axion has long been known to be an excellent candidate for dark matter. We have discovered novel axion dynamics in the early universe, called axion rotations, which may naturally occur as a result of quantum gravity effects and cosmic inflation. This dynamics was overlooked in the extensive literature but has profound consequences. In this talk, I will discuss the example where axion rotations can simultaneously generate axion dark matter and the observed excess of matter over antimatter in the Universe. Remarkably, rich phenomenology automatically arises with sharp, distinct, and correlated predictions. These include specific axion properties, unique gravitational wave signals, and correlated mass scales of supersymmetry and neutrinos. Models with decaying heavy axions may be tested by neutrino experiments such as DUNE and long-lived particle searches at the LHC. Thus far, axion rotations have added fuel to experimental efforts and paved new theory research avenues, opening up resolutions to the deepest cosmological mysteries with discoverable signatures.