Multi-scalar theories of gravity with direct matter couplings and their parametrized post-Newtonian parameters

Understand

We study theories of gravity including, in addition to the metric, several scalar fields in the gravitational sector.

• The particularity of this work is that we allow for direct couplings between these gravitating scalars and the matter sector, which can generally be different for the source and the probe of gravity, in addition to the universal interactions generated by the Jordan frame metric.
• The weak gravity regime of this theory, which would describe solar-system experiments, is studied using the parametrized post-Newtonian (PPN) formalism.
• We derive the expression of the ten parameters of this formalism.