f(R) gravity k-Essence late-time phenomenology

Cosmology of F(T) Gravity and k-Essence

Quantum Gravity Phenomenology

I give a brief non-technical review of " Quantum Gravity Phenomenology " and in particular I describe some studies which should soon allow to establish valuable data-based constraints on the short-distance structure of spacetime. The " quantum-gravity problem " has been studied for more than 70 years, but we still do not have a single experimental result whose interpretation requires us to advo...

Dynamics of K-essence

There are a number of mathematical theorems in the literature on the dynamics of cosmological models with accelerated expansion driven by a positive cosmological constant Λ or a nonlinear scalar field with potential V (quintessence) which do not assume homogeneity and isotropy from the beginning. The aim of this paper is to generalize these results to the case of k-essence models which are defi...

Reconstructing K-essence

We present a model independent method of reconstructing the Lagrangian for the k-essence field driving the present acceleration of the universe. We consider the simplest k-essence model for which the potential is constant. Later we use three parametrizations for the Hubble parameter H(z), consistent with recent the SN1a data, to yield the Lagrangian F . Our reconstruction program does not gener...

Atypical k-essence cosmologies

We analyze the implications of having a divergent speed of sound in k-essence cosmological models. We first study a known theory of that kind, for which the Lagrangian density depends linearly on the time derivative of the k-field. We show that consistency requires that the potential of the k-field be of the inverse square form. Then, we review the known result that the corresponding power-law ...