Speaker
Description
Multiple axions may emerge in the low-energy effective theory of Nature. Generically, the potentials describing these axion fields are non-diagonal, such that a QCD axion might mix with one or more other axion-like-particles. QCD instanton effects render mixing between such states temperature-dependent. We explore how this mass-mixing can impact dark matter production through the misalignment mechanism. We provide an analytic prescription based on the Landau-Zener formalism which allows us to capture non-adiabatic conversion between the mass eigenstates and predict the impact on the present-day relic. This allows us to present haloscope predictions for the patterns that mixed states appear in if a sterile axion mixes with a QCD axion. Our results suggest that if an axion is discovered off the QCD axion line, then the hypothesis that it makes up part of the Strong CP solution predicts the existence of a second state, which can be targeted to confirm the scenario.
