N-flation: Multifield inflationary dynamics and perturbations

Kim, S. A. and Liddle, A. R. (2006) N-flation: Multifield inflationary dynamics and perturbations. Physical Review D, 74 (2). 0235131-0235136. ISSN 0556-2821

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Abstract

We carry out numerical investigations of the dynamics and perturbations in the Nflation model of Dimopoulos et al. (2005). This model features large numbers of scalar fields with different masses, which can cooperate to drive inflation according to the assisted inflation mechanism. We extend previous work to include random initial conditions for the scalar fields, and explore the predictions for density perturbations and the tensor-to-scalar ratio. The tensor-to-scalar ratio depends only on the number of e-foldings and is independent of the number of fields, their masses, and their initial conditions. It therefore always has the same value as for a single massive field. By contrast, the scalar spectral index has significant dependence on model parameters. While normally multi-field inflation models make predictions for observable quantities which depend also on the unknown field initial conditions, we find evidence of a ‘thermodynamic’ regime whereby the predicted spectral index becomes independent of initial conditions if there are enough fields. Only in parts of parameter space where the mass spectrum of the fields is extremely densely packed is the model capable of satisfying the tight observational constraints from WMAP3 observations.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy
Depositing User: SRO Admin
Date Deposited: 20 Mar 2007
Last Modified: 10 Mar 2017 18:09
URI: http://sro.sussex.ac.uk/id/eprint/1094
Google Scholar:40 Citations

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