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19 February, 2017

posted 19 Feb 2017, 06:17 by Scott Melville   [ updated 19 Feb 2017, 06:17 ]
Extending bimetric models of massive gravity to avoid to rely on the Vainshtein mechanism on local scales and the Higuchi bound on cosmological scales
(5 pages)

In massive bigravity theories, the mass parameters can be promted to functions of a single scalar field, removing the need for the Vainshtein mechanism to match GR at small distances. This modification is argued to be stable on cosmological scales, and to avoid the usual Higuchi bound for the mass paramters on de Sitter backgrounds. The scalar field itself introduces a problematic fifth force, but this can be screened by the chameleon mechanism at small distances.


In order to match the successes of GR in the solar system, massive gravity theories typically rely on a Vainshtein screening mechanism at low distances, where non-linearities effectively screen the effects of the additional massive degrees of freedom. The underlying idea here is to promote the graviton mass to an independent field, with a vanishing vev, effectively replacing the need for a screening mechanism with an additional degree of freedom.