Multi-field galileons and higher co-dimension branes

TL;DR

This paper develops a multi-field extension of galileon theories derived from higher co-dimension branes, revealing a unique interaction structure, de Sitter solutions, and a non-renormalization property.

Contribution

It introduces a restrictive multi-galileon theory from higher co-dimension branes, extending the probe brane perspective and analyzing its properties and quantum stability.

Findings

Derived a unique multi-galileon interaction with a single coupling.

Found de Sitter-like self-accelerating solutions with ghost conditions.

Proved a non-renormalization theorem for multi-galileons.

Abstract

In the decoupling limit, the DGP model reduces to the theory of a scalar field pi, with interactions including a specific cubic self-interaction - the galileon term. This term, and its quartic and quintic generalizations, can be thought of as arising from a probe 3-brane in a 5-dimensional bulk with Lovelock terms on the brane and in the bulk. We study multi-field generalizations of the galileon, and extend this probe brane view to higher co-dimensions. We derive an extremely restrictive theory of multiple galileon fields, interacting through a quartic term controlled by a single coupling, and trace its origin to the induced brane terms coming from Lovelock invariants in the higher co-dimension bulk. We explore some properties of this theory, finding de Sitter like self accelerating solutions. These solutions have ghosts if and only if the flat space theory does not have ghosts. Finally, we prove a general non-renormalization theorem: multi-field galileons are not renormalized quantum mechanically to any loop in perturbation theory.