Vainshtein regime in Scalar-Tensor gravity: constraints on DHOST theories

Understand

We study the screening mechanism in the most general scalar-tensor theories that leave gravitational waves unaffected and are thus compatible with recent LIGO/Virgo observations.

• Using the effective field theory of dark energy approach, we consider the general action for perturbations beyond linear order, focussing on the quasi-static limit.
• When restricting to the subclass of theories that satisfy the gravitational wave constraints, the fully nonlinear effective Lagrangian contains only three independent parameters.
• One of these, $\beta_1$, is uniquely present in degenerate higher-order theories.