A statistical approach to multifield inflation: many-field perturbations beyond slow roll

Journal Article · Mon Oct 01 04:00:00 EDT 2012 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2012/10/046· OSTI ID:22279655

McAllister, Liam; Xu, Gang ^[1]; Renaux-Petel, Sébastien ^[2]

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1. Department of Physics, Cornell University, Ithaca, NY 14853 (United States)
2. Centre for Theoretical Cosmology, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge (United Kingdom)

We study multifield contributions to the scalar power spectrum in an ensemble of six-field inflationary models obtained in string theory. We identify examples in which inflation occurs by chance, near an approximate inflection point, and we compute the primordial perturbations numerically, both exactly and using an array of truncated models. The scalar mass spectrum and the number of fluctuating fields are accurately described by a simple random matrix model. During the approach to the inflection point, bending trajectories and violations of slow roll are commonplace, and 'many-field' effects, in which three or more fields influence the perturbations, are often important. However, in a large fraction of models consistent with constraints on the tilt the signatures of multifield evolution occur on unobservably large scales. Our scenario is a concrete microphysical realization of quasi-single-field inflation, with scalar masses of order H, but the cubic and quartic couplings are typically too small to produce detectable non-Gaussianity. We argue that our results are characteristic of a broader class of models arising from multifield potentials that are natural in the Wilsonian sense.

• OSTI ID: 22279655
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 10 Vol. 2012; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
APPROXIMATIONS
COSMOLOGY
ENERGY SPECTRA
EVOLUTION
INFLATIONARY UNIVERSE
LIMITING VALUES
MASS
MASS SPECTRA
PERTURBATION THEORY
POTENTIALS
SCALARS
STRING MODELS
STRING THEORY