Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Collective Phenonema in the Interaction of Radiation with Matter   The aim of this communication is to present in a concentrated form the main
ideas of a method, developed by the author, for treating strongly
nonequilibrium collective phenomena typical of the interaction of radiation
with matter, as well as to give a survey of several applications of the method.
The latter is called the Scale Separation Approach since its basic techniques
rely on the possibility of separating different space-time scales in
nonequilibrium statistical systems. This approach is rather general and can be
applied to diverse physical problems, several of which are discussed here.
These problems are: Superradiance of nuclear spins, filamentation in resonant
media, semiconfinement of neutral atoms, negative electric current, and
collective liberation of light.

29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
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The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
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The categories of this paper are: adap-org
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol