Bimetric gravity is cosmologically viable
Number of Authors: 5
2015 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 748, 37-44 p.Article in journal (Refereed) Published
Bimetric theory describes gravitational interactions in the presence of an extra spin-2 field. Previous work has suggested that its cosmological solutions are generically plagued by instabilities. We show that by taking the Planck mass for the second metric, M-f, to be small, these instabilities can be pushed back to unobservably early times. In this limit, the theory approaches general relativity with an effective cosmological constant which is, remarkably, determined by the spin-2 interaction scale. This provides a late-time expansion history which is extremely close to Lambda CDM, but with a technically-natural value for the cosmological constant. We find M-f should be no larger than the electroweak scale in order for cosmological perturbations to be stable by big-bang nucleosynthesis. We further show that in this limit the helicity-0 mode is no longer strongly-coupled at low energy scales.
Place, publisher, year, edition, pages
2015. Vol. 748, 37-44 p.
Modified gravity, Massive gravity, Background cosmology, Cosmic acceleration, Dark energy, Bimetric gravity, Bigravity
IdentifiersURN: urn:nbn:se:su:diva-120887DOI: 10.1016/j.physletb.2015.06.062ISI: 000359146200008OAI: oai:DiVA.org:su-120887DiVA: diva2:945044