  Weyl semimetal is a solid material with isolated touching points between
conduction and valence bands in its Brillouin zone -- Weyl points. Low energy
excitations near these points exhibit a linear dispersion and act as
relativistic massless particles. Weyl points are stable topological objects
robust with respect to most perturbations. We study effects of weak disorder on
the spectral and transport properties of Weyl semimetals in the limit of low
energies. We use a model of Gaussian white-noise potential and apply
dimensional regularization scheme near three dimensions to treat divergent
terms in the perturbation theory. In the framework of self-consistent Born
approximation, we find closed expressions for the average density of states and
conductivity. Both quantities are analytic functions in the limit of zero
energy. We also include interference terms beyond the self-consistent Born
approximation up to the third order in the disorder strength. These
interference corrections are stronger than the mean-field result and
non-analytic as functions of energy. Our main result is the dependence of
conductivity (in units $e^2/h$) on the electron concentration $\sigma =
\sigma_0 - 0.891\, n^{1/3} + 0.115\, (n^{2/3}/\sigma_0) \ln|n|$.
