Scale Invariance in Newton-Cartan and Ho\v{r}ava-Lifshitz Gravity

Abstract

We present a detailed analysis of the construction of $z=2$ and $z\neq2$ scale invariant Ho\v{r}ava-Lifshitz gravity. The construction procedure is based on the realization of Ho\v{r}ava-Lifshitz gravity as the dynamical Newton-Cartan geometry as well as a non-relativistic tensor calculus in the presence of the scale symmetry. An important consequence of this method is that it provides us the necessary mechanism to distinguish the local scale invariance from the local Schr\"odinger invariance. Based on this result we discuss the $z=2$ scale invariant Ho\v{r}ava-Lifshitz gravity and the symmetry enhancement to the full Schr\"odinger group.