Phantom energy mediates a long-range repulsive force

TL;DR

This paper explores scalar field models with non-standard kinetic terms, revealing that phantom energy can produce a long-range repulsive force, potentially leading to clustering of dark energy and modified gravitational effects.

Contribution

It derives cosmological perturbation equations and Yukawa corrections for general scalar field models, highlighting the unique effects of phantom energy and a generalized Brans-Dicke theory.

Findings

Phantom energy induces a negative coupling, leading to a repulsive long-range force.

Dark energy may cluster on astrophysical scales.

Newtonian effects depend on a single parameter in the generalized Brans-Dicke model.

Abstract

Scalar field models with non-standard kinetic terms have been proposed in the context of k-inflation, of Born-Infeld lagrangians, of phantom energy and, more in general, of low-energy string theory. In general, scalar fields are expected to couple to matter inducing a new interaction. In this paper I derive the cosmological perturbation equations and the Yukawa correction to gravity for such general models. I find three interesting results: first, when the field behaves as phantom energy (equation of state less than -1) then the coupling strength is negative, inducing a long-range repulsive force; second, the dark energy field might cluster on astrophysical scales; third, applying the formalism to a Brans-Dicke theory with general kinetic term it is shown that its Newtonian effects depend on a single parameter that generalizes the Brans-Dicke constant.