  We theoretically study the quantum transport in three-dimensional Weyl
electron system in the presence of the charged impurity scattering using a
self-consistent Born approximation (SCBA). The scattering strength is
characterized by the effective fine structure constant $\alpha$, which depends
on the dielectric constant and the Fermi velocity of the linear band. We find
that the Boltzmann theory fails at the band touching point, where the
conductivity takes a nearly constant value almost independent of $\alpha$, even
though the density of states linearly increases with $\alpha$. There the
magnitude of the conductivity only depends on the impurity density. The
qualitative behavior is quite different from the case of the Gaussian
impurities, where the minimum conductivity vanishes below a certain critical
impurity strength.
