Spectral function of the two-dimensional system of massless Dirac electrons

We determine the one-particle spectral function for the two-dimensional system of massless Dirac electrons interacting via the long-range Coulomb interaction. The electron self-energy is calculated within the G0W0 approximation, paying particular attention to the contribution coming from the collective plasmon mode. We find that, due to the acoustic plasmon dispersion, the spectral function has a renormalized quasi-particle δ-peak at the chemical potential along with a side band for the Fermi wave vector together with a wide structure with a pronounced spectral weight near the Dirac point. The present approach is appropriate for the wide range of energy scales given by the plasmon energy which may be probed in angle-resolved photoemission spectroscopy (ARPES) experiments.