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arXiv · 0910.1353

Observational Signatures of Gravitational Couplings in DBI Inflation

Damien A. Easson·Shinji Mukohyama·Brian A. Powell
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Abstract

In scalar-tensor theories the scalar fields generically couple nontrivially to gravity. We study the observable properties of inflationary models with non-minimally coupled inflaton and Dirac-Born-Infeld (DBI) kinetic term. Within the assumptions of the priors of our Monte-Carlo simulations we find these models can generate new interesting observable signatures. Our discussion focuses on string theory inspired phenomenological models of relativistic D-brane inflation. While successful string theory constructions of ultra-violet DBI brane inflation remain elusive, we show that in suitable regions of the parameter space it is possible to use cosmological observables to probe the non-minimial coupling. Fortunately, the most observationally promising range of parameters include models yielding intermediate levels of non-gaussianity in the range consistent with WMAP 5-year data, and to be constrained further by the Planck satellite.

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Damien A. Easson, Shinji Mukohyama, Brian A. Powell. 2009-10-07. Observational Signatures of Gravitational Couplings in DBI Inflation. https://doi.org/10.1103/physrevd.81.023512

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