Vainshtein screening in Horndeski theories nonminimally and kinetically coupled to ordinary matter

We study the Vainshtein screening mechanism in Horndeski theories in the presence of a scalar field phi nonminimally and kinetically coupled to ordinary matter field. A general interacting Lagrangian describing this coupling is characterized by energy transfer f(1) and momentum exchange f(2). For a spherically symmetric configurations on top of the cosmological background, we investigate the static perturbations in linear and nonlinear regimes with respect to the scalar field perturbation. In the former regime, the parametrized post-Newtonian parameter generally deviates from unity as long as the matter coupling or G(4,phi) exists. On the other hand, in the latter regime, we show that the nonlinear self-interaction term of scalar field successfully activates the Vainshtein mechanism even in the presence of the couplings f(1) and f(2). The gravitational potentials recover the Newtonian behavior deep inside the Vainshtein radius. The bounds on coupling terms not to substantially change the Vainshtein radius are also given.

Automated summary

This study investigates the Vainshtein screening mechanism and the coupling between scalar field and ordinary matter field in Horndeski theories. It finds that the effectiveness of this mechanism in linear and nonlinear perturbations depends on the coupling terms.