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

Understand

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 $\gamma=0.2$: $\Omega_m=0.291\pm0.004^{+0.008+0.012}_{-0.007-0.011}$, $h=0.701\pm0.002\pm0.005\pm0.007$.