Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Directed Percolation Process Advected by Compressible Velocity Field   The directed percolation process in the vicinity of non-equilibrium phase
transition is studied by the means of field theoretic methods. It will be
assumed that percolation takes place in a compressible environment, which will
be generated by the modified Kraichnan model. We will discuss differ- ences
with the incompressible case and describe how the given model can be
renormalized. The renormalization constants will be given to the one-loop
order.

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The categories of this paper are: gr-qc
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The categories of this paper are: adap-org
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The categories of this paper are: hep-ex
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The categories of this paper are: q-bio
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The categories of this paper are: bayes-an
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The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: stat
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-lat
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The categories of this paper are: atom-ph
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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: chao-dyn