Solomon, Adam R.
- Journal Article
Rights / licenseCreative Commons Attribution 4.0 International
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, Mf, 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 ΛCDM, but with a technically-natural value for the cosmological constant. We find Mf 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. Show more
Journal / seriesPhysics Letters B
Pages / Article No.
SubjectModified gravity; Massive gravity; Background cosmology; Cosmic acceleration; Dark energy; Bimetric gravity; Bigravity
Organisational unit03896 - Beisert, Niklas / Beisert, Niklas
615203 - Extended Symmetries in Gauge and Gravity Theories (EC)
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