Gauss-Bonnet Quintessence: Background Evolution, Large Scale Structure and Cosmological Constraints

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  • 22 September 2006
Abstract
We investigate a class of dark energy models in which a scalar field is coupled to the quadratic curvature invariants. Such couplings are present in the one-loop corrected string effective actions and appear generically in theories with extra dimensions. Hence, from the high energy theoretical point of view, these models are much better motivated than perhaps most of the modified gravity or usual (minimally coupled) quintessence models in the literature. We show that from the cosmological and observational perspective, the Gauss-Bonnet quintessence might also be an interesting model of dark energy, because it can 1) Be derived from an action principle, so one can make definite predictions, and it is simple enough to calculate these in practice; 2) Provide a mechanism to viably onset the late time acceleration after a scaling matter era; 3) Alleviate the coincidence problem; 4) Cross the phantom divide at the present and avoid Big Rip; 5) Be compatible with the CMB and LSS power spectra; 6) Present specific features which can be tightly constrained by both local and astrophysical experiments, such as Solar system, supernovae Ia, cosmic microwave background radiation, large scale structure and Big Bang nucleosynthesis; 7) Possibly provide an exit from the acceleration in the future; and 8) Do all this with just two extra parameters (compared to the concordance model) and without introducing unnatural scales into the Lagrangian.

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