What is needed of a tachyon if it is to be the dark energy?

Copeland, Edmund J. ; Garousi, Mohammad R. ; Sami, M. ; Tsujikawa, Shinji (2005) What is needed of a tachyon if it is to be the dark energy? Physical Review D - Particles, Fields, Gravitation and Cosmology, 71 (4). No. pp. given. ISSN 1550-7998

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Official URL: http://prd.aps.org/abstract/PRD/v71/i4/e043003

Related URL: http://dx.doi.org/10.1103/PhysRevD.71.043003


We study a dark energy scenario in the presence of a tachyon field φ with potential V(φ) and a barotropic perfect fluid. The cosmological dynamics crucially depends on the asymptotic behavior of thequantity λ=−MpVφ/V3/2. If λ is a constant, which corresponds to an inverse square potential V(φ)∝φ−2, there exists one stable critical point that gives an acceleration of the Universe at late times. When λ→0 asymptotically, we can have a viable dark energy scenario in which the system approaches an instantaneous critical point that dynamically changes with λ If |λ| approaches infinity asymptotically, the Universe does not exhibit an acceleration at late times. In this case, however, we find an interesting possibility that a transient acceleration occurs in a regime where |λ| is smaller than of order unity.

Item Type:Article
Source:Copyright of this article belongs to The American Physical Society.
ID Code:70524
Deposited On:18 Nov 2011 13:04
Last Modified:18 Nov 2011 13:07

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