Lifting Spacetime's Poincaré Symmetries

Abstract

In the following work, we pedagogically develop 5-vector theory, an evolution of scalar field theory that provides a stepping stone toward a Poincaré-invariant lattice gauge theory. Defining a continuous flat background via the four-dimensional Cartesian coordinates $\{x^a\}$, we `lift' the generators of the Poincaré group so that they transform only the fields existing upon $\{x^a\}$, and do not transform the background $\{x^a\}$ itself. To facilitate this effort, we develop a non-unitary particle representation of the Poincaré group, replacing the classical scalar field with a 5-vector matter field. We further augment the vierbein into a new $5\times5$ fünfbein, which `solders' the 5-vector field to $\{x^a\}$. In so doing, we form a new intuition for the Poincaré symmetries of scalar field theory. This effort recasts `spacetime data', stored in the derivatives of the scalar field, as `matter field data', stored in the 5-vector field itself. We discuss the physical implications of this `Poincaré lift', including the readmittance of an absolute reference frame into relativistic field theory. In a companion paper, we demonstrate that this theoretical development, here construed in a continuous universe, enables the description of a discrete universe that preserves the 10 infinitesimal Poincaré symmetries and their conservation laws.