Primordial fluctuations and non-Gaussianities from multifield DBI Galileon inflation
- 1 November 2011
- journal article
- Published by IOP Publishing in Journal of Cosmology and Astroparticle Physics
- Vol. 2011 (11), 042
- https://doi.org/10.1088/1475-7516/2011/11/042
Abstract
We study a cosmological scenario in which the DBI action governing the motion of a D3-brane in a higher-dimensional spacetime is supplemented with an induced gravity term. The latter reduces to the quartic Galileon Lagrangian when the motion of the brane is non-relativistic and we show that it tends to violate the null energy condition and to render cosmological fluctuations ghosts. There nonetheless exists an interesting parameter space in which a stable phase of quasi-exponential expansion can be achieved while the induced gravity leaves non trivial imprints. We derive the exact second-order action governing the dynamics of linear perturbations and we show that it can be simply understood through a bimetric perspective. In the relativistic regime, we also calculate the dominant contribution to the primordial bispectrum and demonstrate that large non-Gaussianities of orthogonal shape can be generated, for the first time in a concrete model. More generally, we find that the sign and the shape of the bispectrum offer powerful diagnostics of the precise strength of the induced gravity.Keywords
Other Versions
This publication has 100 references indexed in Scilit:
- Orthogonal non-Gaussianities from Dirac–Born–Infeld Galileon inflationClassical and Quantum Gravity, 2011
- Large slow-roll corrections to the bispectrum of noncanonical inflationJournal of Cosmology and Astroparticle Physics, 2011
- Folded resonant non-Gaussianity in general single field inflationJournal of Cosmology and Astroparticle Physics, 2010
- Non-Gaussianity from the bispectrum in general multiple field inflationJournal of Cosmology and Astroparticle Physics, 2008
- Perturbations in generalized multi-field inflationJournal of Cosmology and Astroparticle Physics, 2008
- A microscopic limit on gravitational waves from D-brane inflationPhysical Review D, 2007
- Comparing brane inflation to WMAPJournal of Cosmology and Astroparticle Physics, 2007
- Non-Gaussian inflationary perturbations from the dS/CFT correspondenceJournal of Cosmology and Astroparticle Physics, 2006
- Multithroat brane inflationPhysical Review D, 2005
- Inflation, supergravity, and superstringsPhysical Review D, 1995