Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Phenomenon of the time-reversal-violating photon polarization plane
  rotation by a gas placed to an electric field   T-odd P-odd phenomenon of the photon polarization plane rotation (circular
dichroism) is considered for an atomic (molecules) gas placed to an electric
field. The expression for the T non-invariant polarizability of an atom
(molecule) placed to an electric field is obtained. It is shown that the T-odd
plane rotation angle increases when the interaction energy of an atom
(molecule) with an electric field is the same order as the opposite parity
levels spacing.

15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
6
The categories of this paper are: astro-ph
12
The categories of this paper are: nucl-th