More on QCD ghost dark energy

The difference between the vacuum energy of quantum fields in Minkowski space and in a Friedmann-Robertson-Walker universe might be related to the observed dark energy. The vacuum energy of the Veneziano ghost field introduced to solve the U(1)(A) problem in QCD is of the form H + O(H-2). Based on this, we study the dynamical evolution of a phenomenological dark energy model whose energy density is of the form alpha H + beta H-2. In this model, the universe approaches a de Sitter phase at late times. We fit the model with current observational data, including SnIa, BAO, CMB, BBN, the Hubble parameter, and the growth rate of matter perturbation. It shows that the universe begins to accelerate at redshift z similar to 0.75, and this model is consistent with current data. In particular, this model fits the data of the growth factor well as the Lambda CDM model.