Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Three-dimensional Lorentz model in a magnetic field : exact and
  Chapman-Enskog solutions   We derive the exact solution of the Boltzmann kinetic equation for the
three-dimensional Lorentz model in the presence of a constant and uniform
magnetic field. The velocity distribution of the electrons reduces
exponentially fast to its spherically symmetric component. In the long time
hydrodynamic limit there remains only the diffusion process governed by an
anisotropic diffusion tensor. The systematic way of building the Chapman-Enskog
solutions is described.

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The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
3
The categories of this paper are: physics
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
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The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg