Vainshtein mechanism in second-order scalar-tensor theories

TL;DR

This paper investigates how the Vainshtein mechanism operates in second-order scalar-tensor theories, demonstrating that it can recover General Relativity near matter sources even with strong field couplings, ensuring compatibility with local gravity tests.

Contribution

The study derives the Vainshtein radius in second-order scalar-tensor theories with matter coupling, extending understanding to models like Galileon and Brans-Dicke theories with cosmic acceleration implications.

Findings

Vainshtein mechanism effectively screens modifications to gravity.

Corrections to gravitational potentials are small enough for local tests.

Models can explain cosmic acceleration while satisfying gravity constraints.

Abstract

In second-order scalar-tensor theories we study how the Vainshtein mechanism works in a spherically symmetric background with a matter source. In the presence of the field coupling $F(\phi)=e^{-2Q\phi}$ with the Ricci scalar $R$ we generally derive the Vainshtein radius within which the General Relativistic behavior is recovered even for the coupling $Q$ of the order of unity. Our analysis covers the models such as the extended Galileon and Brans-Dicke theories with a dilatonic field self-interaction. We show that, if these models are responsible for the cosmic acceleration today, the corrections to gravitational potentials are generally small enough to be compatible with local gravity constraints.