Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dynamical density response and optical conductivity in topological
  metals   Topological metals continue to attract attention as novel gapless states of
matter. While there by now exists an exhaustive classification of possible
topologically nontrivial metallic states, their observable properties, that
follow from the electronic structure topology, are less well understood. Here
we present a study of the electromagnetic response of three-dimensional
topological metals with Weyl or Dirac nodes in the spectrum, which systematizes
and extends earlier pioneering studies. In particular, we argue that a
smoking-gun feature of the chiral anomaly in topological metals is the
existence of propagating chiral density modes even in the regime of weak
magnetic fields. We also demonstrate that the optical conductivity of such
metals exhibits an extra peak, which exists on top of the standard metallic
Drude peak. The spectral weight of this peak is transferred from high
frequencies and its width is proportional to the chiral charge relaxation rate.

12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th