Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: String Perturbation Theory on the Schwinger-Keldysh Time Contour   We perform the large-$N$ expansion in the Schwinger-Keldysh formulation of
non-equilibrium quantum systems with matrix degrees of freedom, and study
universal features of the anticipated dual string theory. We find a rich
refinement of the topological genus expansion: In the original formulation, the
future time instant where the forward and backward branches of the
Schwinger-Keldysh time contour meet is associated with its own worldsheet genus
expansion. After the Keldysh rotation, the worldsheets decompose into a
classical and quantum part.

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The categories of this paper are: nlin
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The categories of this paper are: plasm-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: supr-con
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The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
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The categories of this paper are: ao-sci
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: econ
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The categories of this paper are: nucl-th
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The categories of this paper are: physics
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The categories of this paper are: dg-ga