de Sitter Galileon

TL;DR

This paper extends Galileon symmetry to de Sitter space using a probe-brane approach in higher dimensions, resulting in ghost-free invariants with potential cosmological applications.

Contribution

It introduces a generalized Galileon framework on de Sitter backgrounds via a probe-brane construction, maintaining symmetry and avoiding ghosts.

Findings

Lovelock invariants on the brane preserve Poincaré symmetry from the bulk.

Non-relativistic limit maintains Galileon symmetry on de Sitter.

Models are free of ghost-like pathologies and have cosmological relevance.

Abstract

We generalize the Galileon symmetry and its relativistic extension to a de Sitter background. This is made possible by studying a probe-brane in a flat five-dimensional bulk using a de Sitter slicing. The generalized Lovelock invariants induced on the probe brane enjoy the induced Poincar\'e symmetry inherited from the bulk, while living on a de Sitter geometry. The non-relativistic limit of these invariants naturally maintain a generalized Galileon symmetry around de Sitter while being free of ghost-like pathologies. We comment briefly on the cosmology of these models and the extension to the AdS symmetry as well as generic FRW backgrounds.