  Optical properties of two-dimensional massless Dirac fermions are considered
by the formalism of pseudospin precession equations which provides an easy and
natural semiphenomenological way to include correlation effects. It is shown
that the latter are negligible, with the only assumption that the system under
consideration is normal Fermi liquid. This result probably explains recent
experimental data on the universal optical conductivity of graphene (Nair R. R.
et al, Science 320 (2008) 1308).
