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

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.

Note:

12 pages, 3 figures, the published version

95.36.+x
98.80.Cq
98.80.Es
effective field theory
dark energy
phantom: crossing
cosmic background radiation
baryon: oscillation: acoustic
cosmological model
dark matter: coupling

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

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