Goldstone models of modified gravity

Understand

We investigate scalar-tensor theories where matter couples to the scalar field via a kinetically dependent conformal coupling.

• These models can be seen as the low-energy description of invariant field theories under a global Abelian symmetry.
• The scalar field is then identified with the Goldstone mode of the broken symmetry.
• It turns out that the properties of these models are very similar to the ones of ultralocal theories where the scalar-field value is directly determined by the local matter density.