Bimetric structure formation: Non-Gaussian predictions

Joao Magueijo, Johannes Noller, Federico Piazza

Research output: Contribution to journalArticlepeer-review


The minimal bimetric theory employing a disformal transformation between matter and gravity metrics is known to produce exactly scale-invariant fluctuations. It has a purely equilateral non-Gaussian signal, with an amplitude smaller than that of Dirac Born Infeld inflation (with opposite sign) but larger than standard inflation. We consider nonminimal bimetric models, where the coupling B appearing in the disformal transformation ĝμν = gμν−B∂μϕ∂νϕ can run with ϕ. For power-law B(ϕ) these models predict tilted spectra. For each value of the spectral index, a distinctive distortion to the equilateral property can be found. The constraint between this distortion and the spectral index can be seen as a “consistency relation” for nonminimal bimetric models.
Original languageEnglish
Article number043521
JournalPhysical Review D
Publication statusPublished - 2010


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