Scalar-tensor theory with EGB term from Einstein Chern-Simons gravity

TL;DR

This paper derives a four-dimensional scalar-tensor gravity theory with a Gauss-Bonnet term from a five-dimensional Einstein Chern-Simons gravity via Randall-Sundrum compactification, revealing new gravitational degrees of freedom.

Contribution

It introduces a novel derivation of scalar-tensor gravity with Gauss-Bonnet term from higher-dimensional Einstein Chern-Simons gravity, expanding the understanding of gravitational degrees of freedom.

Findings

Derivation of 4D scalar-tensor gravity with Gauss-Bonnet term

Connection to Horndeski theory

Introduction of new gravitational degrees of freedom

Abstract

It is shown that the compactification a la Randall Sundrum of the so called, five dimensional Einstein Chern Simons action gravity leads to an action for a four dimensional scalar tensor gravity that includes a Gauss Bonnet term, which belongs to a particular case of the action of the Horndeski theory. The five dimensional action includes new gravitational degrees of freedom that were introduced requiring that the action be invariant under symmetries greater than the usual Poincare or (A)dS symmetries, namely the so called generalized Poincare algebras B5.