  We study the resistivity of three-dimensional semimetals with linear
dispersion in the presence of on-site electron-electron interaction. The
well-known quadratic temperature dependence of the resistivity of conventional
metals is turned into an unusual $T^6$-behavior. An analogous change affects
the thermal transport, preserving the linearity in $T$ of the ratio between
thermal and electrical conductivities. These results hold from weak coupling up
to the non-perturbative region of the Mott transition. Our findings yield a
natural explanation for the hitherto not understood large exponents
characterizing the temperature-dependence of transport experiments on various
topological semimetals.
