  Frequency dependent conductivity of Coulomb interacting massless Dirac
fermions coupled to random scalar and random vector potentials is found as a
function of frequency in the regime controlled by a line of fixed points. Such
model provides a low energy description of a weakly rippled suspended graphene.
The main finding is that at the neutrality point the a.c. conductivity is not
frequency independent and may either increase or decrease with decreasing
frequency, depending on the values of the disorder variances $\Delta_{\phi}$,
$\Delta_{A}$ and the Coulomb coupling $\alpha=e^2/(\eps v_F)$. The low
frequency behavior is characterized by the values of two dimensionless
parameters $\gamma=\Delta_{\phi}/\alpha^2$ and $\Delta_A$ which are RG
invariants, and for small values of which the electron-hole "puddles" are
effectively screened making the results asymptotically exact.
