Dark Energy Coupled with Relativistic Dark Matter in Accelerating Universe

Recent observations favour an accelerating Universe dominated by the dark energy. We take the effective Yang-Mills condensate as the dark energy and couple it to a relativistic matter which is created by the decaying condensate. The dynamic evolution has asymptotic behaviour with finite constant energy densities, and the fractional densities Ω_Λ ～ 0.7 for dark energy and Ω_m ～ 0.3 for relativistic matter are achieved at proper values of the decay rate. The resulting expansion of the Universe is in the de Sitter acceleration.