Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electron polarizability of crystalline solids in quantizing magnetic
  fields and topological gap numbers   A theory of the static electron polarizability of crystals whose energy
spectrum is modified by quantizing magnetic fields is presented. It is argued
that The polarizability is strongly affected by non-dissipative Hall currents
induced by the presence of crossed electric and magnetic fields: these can even
change its sign. Results are illustrated in detail for a two dimensional square
lattice. The polarizability and the Hall conductivity are respectively linked
to the two topological quantum numbers entering the so--called Diophantine
equation. These numbers could in principle be detected in actual experiments.

1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat