Gravity with more or less gauging
Abstract
General Relativity is usually formulated as a theory with gauge invariance under the diffeomorphism group, but there is a 'dilaton' formulation where it is in addition invariant under Weyl transformations, and a 'unimodular' formulation where it is only invariant under the smaller group of special diffeomorphisms. Other formulations with the same number of gauge generators, but a different gauge algebra, also exist. These different formulations provide examples of what we call 'inessential gauge invariance', 'symmetry trading' and 'linking theories'; they are locally equivalent, but may differ when global properties of the solutions are considered. We discuss these notions in the Lagrangian and Hamiltonian formalism.
Cite
@article{arxiv.1805.11626,
title = {Gravity with more or less gauging},
author = {Steffen Gielen and Rodrigo de Leon Ardon and Roberto Percacci},
journal= {arXiv preprint arXiv:1805.11626},
year = {2018}
}
Comments
24 pages, 1 table, 1 figure; minor changes to match published version