Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the electric activity of superfluid systems   The Keldysh's theory of superfluidity of rarefied electron-hole gas is
generalized to a case of possible pair polarizability. It was shown that
inhomogeneity of the system leads to dipole moment which is proportional to the
density gradient. The dipole moment appears also near boundaries of the system.
It was determined that quantized vortices in a magnetic field carry a real
electric charge. In He II at H=10 T and helium rotation velocity $10^2$
s$^{-1}$ the charge density is about $10^4e$ cm$^{-3}$, where $e$ is the
electron charge.

33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio