Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The ratio of viscosity to entropy density in a pion gas satisfies the
  KSS holographic bound   We evaluate the ratio of shear viscosity to entropy density in a pion gas
employing the Uehling-Uehlenbeck equation and experimental phase-shifts
parameterized by means of the SU(2) Inverse Amplitude Method. We find that the
ratio for this monocomponent gas stays well above the KSS 1/(4 pi) bound. We
find similar results with other sets of phase shifts and conclude the bound is
nowhere violated.

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The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
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The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
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The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
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The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
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The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
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The categories of this paper are: q-fin