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

Edmund J. Copeland*, Mohammad R. Garousi, M. Sami, Shinji Tsujikawa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

232 Citations (Scopus)


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 the quantity λ = -MpVφ/V3/2. die;/í3/É2. 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.

Original languageEnglish
Article number043003
Pages (from-to)043003-1-043003-11
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number4
Publication statusPublished - 2005 Feb
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)


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