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Cosmology in bimetric theory with an effective composite coupling to matter
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Oskar Klein Centre, AlbaNova University Centre, Sweden.
2015 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, Vol. 2015, no 4, 008Article in journal (Refereed) Published
Abstract [en]

We study the cosmology of bimetric theory with a composite matter coupling. We find two possible branches of background evolution. We investigate the question of stability of cosmological perturbations. For the tensor and vector perturbations, we derive conditions on the absence of ghost and gradient instabilities. For the scalar modes, we obtain conditions for avoiding ghost degrees. In the first branch, we find that one of the scalar modes becomes a ghost at the late stages of the evolution. Conversely, this problem can be avoided in the second branch. However, we also find that the constraint for the second branch prevents the doubly coupled matter fields from being the standard ingredients of cosmology. We thus conclude that a realistic and stable cosmological model requires additional minimally coupled matter fields.

Place, publisher, year, edition, pages
2015. Vol. 2015, no 4, 008
Keyword [en]
Dark energy theory, Modified gravity
National Category
Physical Sciences
URN: urn:nbn:se:kth:diva-166982DOI: 10.1088/1475-7516/2015/04/008ISI: 000355742500009ScopusID: 2-s2.0-84927512039OAI: diva2:813669
EU, FP7, Seventh Framework Programme, 306425EU, European Research Council, ERC-2011-StG 279363-HiDGR; 24540256

QC 20150525

Available from: 2015-05-25 Created: 2015-05-21 Last updated: 2015-06-25Bibliographically approved

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Heisenberg, Lavinia
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