Coleman-Weinberg dynamics of ultralight scalar dark matter and GeV-scale right-handed neutrinos

Abstract: We consider an extension of the Standard Model by three singlet fermions and one singlet real scalar field. The scalar is an ultralight dark matter candidate whose abundance is set by dynamically induced misalignment from the Higgs portal. We focus on parameter space where the Coleman-Weinberg potential both fixes the dark matter relic abundance, and predicts the mass scale of right-handed neutrinos. The model prefers scalar masses in the range of $10 ~{\rm {\mu}eV} \lesssim m_{\phi} \lesssim 10 ~{\rm meV}$, and can be tested via direct searches for a light scalar (e.g. fifth force tests), or by searching for right-handed neutrinos in laboratory experiments.