Revisiting fifth forces in the Galileon model

TL;DR

This paper reevaluates the constraints on fifth forces mediated by Galileon fields, showing that previous experimental bounds are less restrictive than once thought, due to the Vainshtein effect's screening.

Contribution

It provides a revised analysis of fifth force constraints in Galileon models, highlighting weaker experimental bounds than previously established.

Findings

Parameters are less constrained by experiments than earlier estimates.

The Vainshtein effect significantly suppresses the fifth force near heavy sources.

Revised bounds impact the viability of certain Galileon theories.

Abstract

A Galileon field is one which obeys a spacetime generalization of the non-relativistic Galilean invariance. Such a field may possess non-canonical kinetic terms, but ghost-free theories with a well-defined Cauchy problem exist, constructed using a finite number of relevant operators. The interactions of this scalar with matter are hidden by the Vainshtein effect, causing the Galileon to become weakly coupled near heavy sources. We revisit estimates of the fifth force mediated by a Galileon field, and show that the parameters of the model are less constrained by experiment than previously supposed.