Solar System experiments do not yet veto modified gravity models

TL;DR

This paper revisits the equivalence between modified gravity and scalar-tensor theories, showing that Solar System experiments do not currently rule out modified gravity models, contrary to previous beliefs.

Contribution

It demonstrates that the dynamical equivalence breaks down in the general relativity limit, challenging prior assumptions about Solar System constraints on modified gravity.

Findings

Dynamical equivalence between theories breaks down in the GR limit

Solar System experiments do not veto modified gravity models

Gauge-independent analysis supports the conclusion

Abstract

The dynamical equivalence between modified and scalar-tensor gravity theories is revisited and it is concluded that it breaks down in the limit to general relativity. A gauge-independent analysis of cosmological perturbations in both classes of theories lends independent support to this conclusion. As a consequence, the PPN formalism of scalar-tensor gravity and Solar System experiments do not veto modified gravity, as previously thought.