Dynamical diffeomorphisms

TL;DR

This paper develops a general effective dynamical framework for spacetime diffeomorphisms within a fixed metric, revealing unique properties and an effective cosmological constant arising from the identity solution.

Contribution

It introduces a novel effective dynamics model for spacetime diffeomorphisms with distinct kinematical and dynamical features, including a conserved energy-momentum tensor with two parts.

Findings

Energy-momentum tensor has two independently conserved components

Background solution corresponds to the identity diffeomorphism

Effective cosmological constant emerges from the background energy-momentum

Abstract

We construct a general effective dynamics for diffeomorphisms of spacetime, in a fixed external metric. Though related to familiar models of scalar fields as coordinates, our models have subtly different properties, both at kinematical and dynamical level. The energy-momentum tensor consists of two independently conserved parts. The background solution is the identity diffeomorphism and the energy-momentum tensor of this solution gives rise to an effective cosmological constant.