  The average density of states of two- and three-dimensional Weyl fermions is
studied in the self-consistent Born approximation (SCBA) and its corrections.
The latter have been organized in terms of a 1/N expansion. It turns out that
an expansion in terms of the disorder strength is not applicable, as previously
mentioned by other authors. Nevertheless, the 1/N expansion provides a
justification of the SCBA as the large N limit of Weyl fermions.
