“School of Physics”

Back to Papers Home
Back to Papers of School of Physics

Paper   IPM / P / 8035
School of Physics
  Title:   What Is Needed of A Tachyon If It Is to Be the Dark Energy?
  Author(s): 
1.  E.J. Copeland
2.  M.R. Garousi
3.  M. Sami
4.  S. Tsujikawa
  Status:   Published
  Journal: Phys. Rev. D
  Vol.:  71
  Year:  2005
  Pages:   043003
  Supported by:  IPM
  Abstract:
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. 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.

Download TeX format
back to top
Clients Logo
Clients Logo
Clients Logo
Clients Logo
Clients Logo
Clients Logo
Clients Logo
Clients Logo
scroll left or right