Dark Energy with Logarithmic Cosmological Fluid

TL;DR

This paper introduces a logarithmic cosmological fluid model for dark energy that naturally explains the small current dark energy density and the universe's acceleration without fine-tuning, using scalar fields.

Contribution

It presents a novel dark energy model based on a logarithmic fluid and constructs dynamical scalar field models that fit current cosmic acceleration observations.

Findings

Model achieves small dark energy density naturally.

Scalar field potentials are explicitly derived.

Numerical consistency with accelerating universe is demonstrated.

Abstract

We propose a dark energy model with a logarithmic cosmological fluid which can result in a very small current value of the dark energy density and avoid the coincidence problem without much fine-tuning. We construct a couple of dynamical models that could realize this dark energy at very low energy in terms of four scalar fields quintessence and discuss the current acceleration of the Universe. Numerical values can be made to be consistent with the accelerating Universe with adjustment of the two parameters of the theory. The potential can be given only in terms of the scale factor, but the explicit form at very low energy can be obtained in terms of the scalar field to yield of the form V(\phi)=\exp(-2\phi)(\frac{4 A}{3}\phi+B). Some discussions and the physical implications of this approach are given.