Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Feynman-Schwinger technique in field theories   In these lectures we introduce the Feynman-Schwinger representation method
for solving nonperturbative problems in field theory. As an introduction we
first give a brief overview of integral equations and path integral methods for
solving nonperturbative problems. Then we discuss the Feynman-Schwinger (FSR)
representation method with applications to scalar interactions. The FSR
approach is a continuum path integral integral approach in terms of covariant
trajectories of particles. Using the exact results provided by the FSR approach
we test the reliability of commonly used approximations for nonperturbative
summation of interactions for few body systems.

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The categories of this paper are: math-ph
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The categories of this paper are: stat
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The categories of this paper are: econ
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: alg-geom
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The categories of this paper are: ao-sci
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The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
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The categories of this paper are: hep-ex