A Minimal Axio-dilaton Dark Sector

Understand

In scalar-tensor theories it is the two-derivative sigma-model interactions that like to compete at low energies with the two-derivative interactions of General Relativity (GR) $\unicode{x2014}$ at least once the dangerous zero-derivative terms of the scalar potential are suppressed (such as by a shift symmetry).

• But nontrivial two-derivative interactions require at least two scalars to exist and so never arise in the single-scalar models most commonly explored.
• Axio-dilaton models provide a well-motivated minimal class of models for which these self-interactions can be explored.
• We review this class of models and investigate whether these minimal two fields can suffice to describe both Dark Matter and Dark Energy.