Slow-roll k-essence
- Department of Physics, College of Humanities and Sciences, Nihon University, Tokyo 156-8550 (Japan)
- Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)
We derive slow-roll conditions for thawing k-essence with a separable Lagrangian p(X,{phi})=F(X)V({phi}). We examine the evolution of the equation of state parameter, w, as a function of the scale factor a, for the case where w is close to -1. We find two distinct cases, corresponding to X{approx_equal}0 and F{sub X}{approx_equal}0, respectively. For the case where X{approx_equal}0 the evolution of {phi} and hence w is described by only two parameters, and w(a) is model independent and coincides with similar behavior seen in thawing quintessence models. This result also extends to nonseparable Lagrangians where X{approx_equal}0. For the case F{sub X}{approx_equal}0, an expression is derived for w(a), but this expression depends on the potential V({phi}), so there is no model-independent limiting behavior. For the X{approx_equal}0 case, we derive observational constraints on the two parameters of the model, w{sub 0} (the present-day value of w), and the K, which parametrizes the curvature of the potential. We find that the observations sharply constrain w{sub 0} to be close to -1, but provide very poor constraints on K.
- OSTI ID:
- 21322445
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 80, Issue 4; Other Information: DOI: 10.1103/PhysRevD.80.043517; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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