Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: WKB versus generalized van Kampen system-size expansion: the stochastic
  logistic equation   Stochastic fluctuations are central to the understanding of extinction
dynamics. In the context of population models they allow for the description of
the transition from the vicinity of a non-trivial fixed point of the
deterministic dynamics to a trivial fixed point, where the population has
become extinct. To characterize analytically the fluctuations of a given
stochastic population model, one can operate within the so-called linear-noise
approximation. Here the fluctuations are taken to be Gaussian, and the
phenomenon of extinction is so rare as to be negligible, for all practical
purposes. When the size of the population becomes small, non-Gaussian
fluctuations are instead found. Two analytical schemes are in principle
available to determine the nature of the distribution of associated
fluctuations: the generalized van Kampen system-size expansion beyond the
conventional order of approximation and a WKB-like method. Here we investigate
the accuracy of these two different approximation schemes, with reference to a
simple stochastic process that converges to the logistic equation in the
deterministic limit.

28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
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The categories of this paper are: bayes-an
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph