Observational constraints on a Yang-Mills condensate dark energy model
  Using the recently released Union2 compilation with 557 Type Ia supernovae, the shift parameter of cosmic microwave background given by the WMAP7 observations, and the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey, we perform the $\chi^2$ analysis on the 1-loop Yang-Mills condensate (YMC) dark energy model. The analysis has been made for both non-coupling and coupling models with $\Omega_{m0}$ and $w_0$ being treated as free parameters. It is found that, $\chi^2_{min}$ = 542.870 at $\Omega_{m0}$ = 0.2701 and $w_0$ = -0.9945 for non-coupling model, and $\chi^2_{min}$ = 542.790 at $\gamma$ = -0.015, $\Omega_{m0}$ = 0.2715 and $w_0$ = -0.9969 for coupling model. Comparing with the $\Lambda$CDM model, the YMC model has a smaller $\chi^2_{min}$, but it has greater values of the Bayesian and Akaike information criteria. Overall, YMC is as robust as $\Lambda$CDM. 
Z. W. Fu, Y. Zhang and M. L. Tong
gr-qc