Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetically-Charged Black Branes and Viscosity/Entropy Ratios   We consider asymptotically-AdS $n$-dimensional black brane solutions in a
theory of gravity coupled to a set of $N$ $p$-form field strengths, in which
the field strengths carry magnetic charges. For appropriately chosen charges,
the metrics are isotropic in the $(n-2)$ transverse directions. However, in
general the field strength configurations break the full Euclidean symmetry of
the $(n-2)$-dimensional transverse space. We then study the linearised equation
for transverse traceless metric perturbations in these backgrounds, and by
employing the Kubo formula we obtain expressions for $\eta/S$, the ratio of
shear viscosity to entropy density. We find that the KSS bound on the ratio
$\eta/S$ is generally violated in these solutions. We also extend the
discussion by including also a dilatonic scalar field in the theory, leading to
solutions that are asymptotically Lifshitz with hyperscaling violation.

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The categories of this paper are: patt-sol
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The categories of this paper are: dg-ga
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The categories of this paper are: econ
0
The categories of this paper are: hep-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: funct-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: solv-int
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The categories of this paper are: adap-org
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The categories of this paper are: nlin
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
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The categories of this paper are: atom-ph