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

TL;DR

This paper investigates how the Vainshtein screening mechanism operates in Horndeski theories with scalar fields that are nonminimally and kinetically coupled to matter, showing that nonlinear interactions restore Newtonian gravity within a certain radius.

Contribution

It demonstrates that nonlinear scalar self-interactions activate the Vainshtein mechanism even with matter couplings, and provides bounds on these couplings to preserve screening.

Findings

Vainshtein mechanism remains effective with matter couplings due to nonlinear interactions.

Parametrized post-Newtonian deviations occur in linear regime if couplings exist.

Gravitational potentials recover Newtonian behavior inside the Vainshtein radius.

Abstract

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.