Notes on ghost dark energy

We study a phenomenological dark energy model which is rooted in the Veneziano ghost of QCD. In this dark energy model, the energy density of dark energy is proportional to Hubble parameter and the proportional coefficient is of the order Lambda(3)(QCD), where Lambda QCD is the mass scale of QCD. The universe has a de Sitter phase at late time and begins to accelerate at redshift around z(acc) similar to 0.6. We fit this model and give the constraints on model parameters, with current observational data including Type Ia supernovea, baryon acoustic oscillation, cosmic microwave background, big bang nucleosynthesis, and Hubble parameter data. We also study the cosmological evolution of the dark energy with interaction with cold dark matter.