The basic building block for Lorentz-invariant and ghost-free massive gravity is the square root of the combination g−1η, where g−1 is the inverse of the physical metric and η is a reference metric. Since the square root of a matrix is not uniquely defined, it is possible to have physically inequivalent potentials corresponding to different branches. We show that around the Minkowski background, the only perturbatively well-defined branch is the potential proposed by de Rham, Gabadadze and Tolley. On the other hand, if Lorentz symmetry is broken spontaneously, other potentials exist with a standard perturbative expansion. We show this explicitly building new Lorentz-invariant, ghost-free massive gravity potentials for theories that in the background preserve rotational invariance but break Lorentz boosts.
Titolo: | New Branches of Massive Gravity |
Autori: | |
Data di pubblicazione: | 2015 |
Rivista: | |
Handle: | http://hdl.handle.net/11697/15965 |
Appare nelle tipologie: | 1.1 Articolo in rivista |