Cosmological dynamics of a dirac-born-infeld field

Edmund J. Copeland, Shuntaro Mizuno, Maryam Shaeri

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

We analyze the dynamics of a Dirac-Born-Infeld (DBI) field in a cosmological setup which includes a perfect fluid. Introducing convenient dynamical variables, we show that the evolution equations form an autonomous system when the potential and the brane tension of the DBI field are arbitrary power law or exponential functions of the DBI field. In particular we find scaling solutions can exist when powers of the field in the potential and warp factor satisfy specific relations. A new class of fixed-point solutions are obtained corresponding to points which initially appear singular in the evolution equations, but on closer inspection are actually well defined. In all cases, we perform a phase-space analysis and obtain the late-time attractor structure of the system. Of particular note when considering cosmological perturbations in DBI inflation is a fixed-point solution where the Lorentz factor is a finite large constant and the equation of state parameter of the DBI field is w=-1. Since in this case the speed of sound cs becomes constant, the solution can be thought to serve as a good background to perturb about.

Original languageEnglish
Article number123501
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume81
Issue number12
DOIs
Publication statusPublished - 2010
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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