### 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 language | English |
---|---|

Article number | 123501 |

Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |

Volume | 81 |

Issue number | 12 |

DOIs | |

Publication status | Published - 2010 |

Externally published | Yes |

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### ASJC Scopus subject areas

- Nuclear and High Energy Physics

### Cite this

*Physical Review D - Particles, Fields, Gravitation and Cosmology*,

*81*(12), [123501]. https://doi.org/10.1103/PhysRevD.81.123501

**Cosmological dynamics of a dirac-born-infeld field.** / Copeland, Edmund J.; Mizuno, Shuntaro; Shaeri, Maryam.

Research output: Contribution to journal › Article

*Physical Review D - Particles, Fields, Gravitation and Cosmology*, vol. 81, no. 12, 123501. https://doi.org/10.1103/PhysRevD.81.123501

}

TY - JOUR

T1 - Cosmological dynamics of a dirac-born-infeld field

AU - Copeland, Edmund J.

AU - Mizuno, Shuntaro

AU - Shaeri, Maryam

PY - 2010

Y1 - 2010

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=77954642260&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77954642260&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.81.123501

DO - 10.1103/PhysRevD.81.123501

M3 - Article

VL - 81

JO - Physical review D: Particles and fields

JF - Physical review D: Particles and fields

SN - 0556-2821

IS - 12

M1 - 123501

ER -