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N-flation: multifield inflationary dynamics and perturbations

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journal contribution
posted on 2023-06-07, 19:29 authored by Soo Kim, Andrew Liddle
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 multifield 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.

History

Publication status

  • Published

File Version

  • Published version

Journal

Physical Review D

ISSN

0556-2821

Issue

2

Volume

74

Page range

0235131-0235136

Department affiliated with

  • Physics and Astronomy Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2012-02-06

First Open Access (FOA) Date

2016-03-22

First Compliant Deposit (FCD) Date

2016-11-10

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