Conformal couplings of Galileons to other degrees of freedom

Abstract

We discuss a formulation of Galileon actions in terms of matrix determinants in four dimensions. This approach allows one to straightforwardly determine derivative couplings between Galileons and scalar or vector degrees of freedom that lead to equations of motion with at most two space-time derivatives. We use this method to easily build generalizations of Galileon set-ups preserving conformal symmetry, finding explicit examples of couplings between Galileons and additional degrees of freedom that preserve the Galileon conformal invariance. We discuss various physical applications of our method and of our results.