Crossing $w=-1$ by a single scalar field coupling with matter and the observational constraints

TL;DR

This paper introduces a logarithmic correction to a dark energy model that naturally avoids the coincidence problem, allows the equation of state to cross -1, and fits observational data well, resembling the Lambda-CDM model at late times.

Contribution

It proposes a new dark energy model with a logarithmic correction that can cross the phantom divide and fits observational data, including a stable tracker solution.

Findings

Model can cross w=-1 smoothly with dark matter interaction.

Best-fit parameters align with observational data.

Non-coupled model mimics Lambda-CDM at late times.

Abstract

Motivated by Yang-Mills dark energy model, we propose a new model by introducing a logarithmic correction. we find that this model can avoid the coincidence problem naturally and gives an equation of state $w$ smoothly crossing -1 if an interaction between dark energy and dark matter exists. It has a stable tracker solution as well. To confront with observations based on the combined data of SNIa, BAO, CMB and Hubble parameter, we obtain the best fit values of the parameters with $1\sigma, 2\sigma, 3\sigma$ errors for the noncoupled model: $\Omega_m=0.276\pm0.008^{+0.016+0.024}_{-0.015-0.022}$, $h=0.699\pm0.003\pm0.006\pm0.008$, and for the coupled model with a decaying rate $\gamma=0.2$: $\Omega_m=0.291\pm0.004^{+0.008+0.012}_{-0.007-0.011}$, $h=0.701\pm0.002\pm0.005\pm0.007$. In particular, it is found that the non-coupled model has a dynamic evolution almost undistinguishable to $\Lambda$CDM at the late-time Universe.