k-essence and extended tachyons in brane-worlds

TL;DR

This paper explores the dynamics of k-essence and extended tachyon fields on a brane-world, revealing diverse cosmological evolutions including bouncing, collapsing, and singularity-ending universes, with specific potentials and kinetic functions analyzed.

Contribution

It introduces a model of k-essence and extended tachyons on a brane-world with novel solutions and analyzes their high and low energy limits, including negative energy tachyon fields.

Findings

Solutions include expanding, contracting, and bouncing universes.

Certain models end in big crunch or big rip.

High and low energy limits yield nearly power law solutions.

Abstract

We study a k-essence field evolving linearly with the cosmic time and the atypical k-essence model on a homogeneous and isotropic flat 3-brane. We show that the k-field is driven by an inverse quadratic polynomial potential. The solutions represent expanding, contracting or bouncing universes with a finite time span and some of them end in a big crunch or a big rip. Besides, by selecting the extended tachyonic kinetic functions we analyze the high and low energy limits of our model, obtaining the nearly power law solution. We introduce a tachyon field with negative energy density and show that the universe evolves between two singularities.