Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Inelastic scattering of electrons by metastable hydrogen atoms in a
  laser field   The inelastic scattering of fast electrons by metastable hydrogen atoms in
the presence of a linearly polarized laser field is theoretically studied in
the domain of moderate field intensities. The interaction of the hydrogen atom
with the laser field is described by first-order time-dependent perturbation
theory, while the projectile electrons interacting with the laser field are
described by the Gordon-Volkov wave functions. An analytic expression is
obtained for the differential scattering cross section in the first-order Born
approximation for laser-assisted inelastic e-H(2s) scattering for the 2s-nl
excitation. Detailed analytical and numerical results are presented for
inelastic scattering accompanied by one-photon absorption, and the angular
dependence and resonance structure of the differential cross sections is
discussed for the 2s -4l excitation of metastable hydrogen.

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The categories of this paper are: cond-mat
11
The categories of this paper are: hep-lat
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex