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

Motivated by the 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 SN Ia, BAO, CMB and Hubble parameter, we obtain the best-fit values of the parameters with 1σ, 2σ, 3σ errors for the non-coupled model: Ωm = 0.276 ± 0.008+0.016+0.024-0.015-0.022, h = 0.699 ± 0.003 ± 0.006 ± 0.008, and for the coupled model with a decaying rate γ = 0.2: Ωm = 0.291 ± 0.004+0.008+0.012-0.007-0.011, h = 0.701 ± 0.002 ± 0.005 ± 0.007. In particular, it is found that the non-coupled model has a dynamic evolution almost indistinguishable to ΛCDM at the late-time Universe.