AC conductivity for a holographic Weyl Semimetal

We study the AC electrical conductivity at zero temperature in a holographic model for a Weyl semimetal. At small frequencies we observe a linear dependence in the frequency. The model shows a quantum phase transition between a topological semimetal (Weyl semimetal phase) with a non vanishing anomalous Hall conductivity and a trivial semimetal. The AC conductivity has an intermediate scaling due to the presence of a quantum critical region in the phase diagram of the system. The phase diagram is reconstructed using the scaling properties of the conductivity. We compare with the experimental data of [1502.03807] obtaining qualitative agreement.
Comment: 27 pages, 5 figures and 3 appendices. Published version; references added, discussion of section 5 extended and typos corrected