2019/04/26 by Sergey Alexandrov, Alexandrov, Sergei, Speziale, Simone · 1 citation
Physics and Astronomy · #Cosmology and Gravitation Theories #Black Holes and Theoretical Physics #Relativity and Gravitational Theory
paper · doi:10.48550/arxiv.1904.11906
We analyze a bi-gravity model based on the first order formalism, having as fundamental variables two tetrads but only one Lorentz connection. We show that on a large class of backgrounds its linearization agrees with general relativity. At the non-linear level, additional degrees of freedom appear, and we reveal the mechanism hiding them around the special backgrounds. We further argue that they do not contain a massive graviton, nor the Boulware-Deser ghost. The model thus propagates only one graviton, whereas the nature of the additional degrees of freedom remains to be investigated. We also present a foliation-preserving deformation of the model, which keeps all symmetries except time diffeomorphisms and has three degrees of freedom.