Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Particle creation in nonstationary large N quantum mechanics   We consider an analog of particle production in a quartic $O(N)$ quantum
oscillator with time-dependent frequency, which is a toy model of particle
production in the dynamical Casimir effect and de Sitter space. We calculate
exact quantum averages, Keldysh propagator, and particle number using two
different methods. First, we employ a kind of rotating wave approximation to
estimate these quantities for small deviations from stationarity. Second, we
extend these results to arbitrarily large deviations using the
Schwinger-Keldysh diagrammatic technique. We show that in strongly
nonstationary situations, including resonant oscillations, loop corrections to
the tree-level expressions effectively result in an additional degree of
freedom, $N \to N + \frac{3}{2}$, which modifies the average number and energy
of created particles.

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The categories of this paper are: q-bio
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The categories of this paper are: stat
30
The categories of this paper are: q-alg
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The categories of this paper are: dg-ga
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The categories of this paper are: ao-sci
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The categories of this paper are: alg-geom
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The categories of this paper are: supr-con
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The categories of this paper are: adap-org
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The categories of this paper are: hep-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: eess
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The categories of this paper are: solv-int
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The categories of this paper are: acc-phys
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The categories of this paper are: nlin
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The categories of this paper are: chem-ph
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The categories of this paper are: q-fin