String-inspired cosmology: a late time transition from a scaling matter era to a dark energy universe caused by a Gauss-Bonnet coupling

Tsujikawa, Shinji ; Sami, M. (2007) String-inspired cosmology: a late time transition from a scaling matter era to a dark energy universe caused by a Gauss-Bonnet coupling Journal of Cosmology and Astroparticle Physics, 2007 (1). No.pp.given. ISSN 1475-7516

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Official URL: http://iopscience.iop.org/1475-7516/2007/01/006

Related URL: http://dx.doi.org/10.1088/1475-7516/2007/01/006

Abstract

The Gauss-Bonnet (GB) curvature invariant coupled to a scalar field Φ can lead to an exit from a scaling matter dominated epoch to a late time accelerated expansion, which is attractive for alleviating the coincidence problem of dark energy. We derive the condition for the existence of cosmological scaling solutions in the presence of the GB coupling for a general scalar field Lagrangian density p(Φ,Χ), where Χ=−(½)(∇Φ)2 is a kinetic term of the scalar field. The GB coupling and the Lagrangian density are restricted to being in the forms f(Φ) αeλΦ and p = Χg(XeλΦ), respectively, where λ is a constant and g is an arbitrary function. We also derive fixed points for such a scaling Lagrangian with a GB coupling f(Φ) αeμΦ and clarify the conditions under which the scaling matter era is followed by a de Sitter solution which can appear in the presence of the GB coupling. Among the scaling models proposed in the current literature, we find that the models which allow such a cosmological evolution are an ordinary scalar field with an exponential potential and a tachyon field with an inverse square potential, although the latter requires a coupling between dark energy and dark matter.

Item Type:Article
Source:Copyright of this article belongs to Institute of Physics.
Keywords:Cosmological Applications of Theories with Extra Dimensions String Theory and Cosmology
ID Code:70512
Deposited On:19 Nov 2011 11:37
Last Modified:19 Nov 2011 11:37

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