  We compute the two-loop interaction correction to the minimal conductivity of
disorder-free intrinsic graphene with the help of dimensional regularization.
The calculation is done in two different ways: via density-density and via
current-current correlation functions. Upon properly renormalizing the
perturbation theory, in both cases, we find that: $\sigma = \sigma_0\,( 1 +
\al\,(19-6\pi)/12) \approx \sigma_0 \,(1 + 0.01\, \al)$, where $\al = e^2 / (4
\pi \hbar v)$ is the renormalized fine structure constant and $\sigma_0 = e^2 /
(4 \hbar)$. Our results are consistent with experimental uncertainties and
resolve a theoretical dispute.
