Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Out of Equilibrium Quantum Field Theory --- Perturbation Theory and
  Generalized Boltzmann Equation   This paper describes perturbative framework, on the basis of the
closed-time-path formalism, in terms of quasiparticle picture for studying
quasiuniform relativistic quantum field systems near equilibrium and
nonequilibrium quasistationary systems. Two calculational schemes are
introduced, the one is formulated on the basis of the initial-particle
distribution function and the one is formulated on the basis of the
``physical''-particle distribution function. It is shown that both schemes are
equivalent and lead to a generalized kinetic or Boltzmann equation. Concrete
procedure of computing a generic amplitude is presented.

37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
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The categories of this paper are: funct-an
6
The categories of this paper are: astro-ph
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The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga
36
The categories of this paper are: cmp-lg