Interacting dark sector with variable vacuum energy

We examine a cosmological scenario where dark matter is coupled to a variable vacuum energy while baryons and photons are two decoupled components for a spatially flat Friedmann-Robertson-Walker spacetime. We apply the chi 2 method to the updated observational Hubble data for constraining the cosmological parameters and analyze the amount of dark energy in the radiation era. We show that our model fulfills the severe bound of Omega(x)(z similar or equal to 1100) < 0.009 at the 2 sigma level, so it is consistent with the recent analysis that includes cosmic microwave background anisotropy measurements from the Planck survey, the Atacama Cosmology Telescope, and the South Pole Telescope along with the future constraints achievable by the Euclid and CMBPol experiments, and fulfills the stringent bound Omega(x)(z similar or equal to 1010) < 0.04 at the 2 sigma level in the big-bang nucleosynthesis epoch.