Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Viscosity Bound, Causality Violation and Instability with Stringy
  Correction and Charge   Recently, it has been shown that if we consider the higher derivative
correction, the viscosity bound conjectured to be $\eta/s=1/4\pi$ is violated
and so is the causality. In this paper, we consider medium effect and the
higher derivative correction simultaneously by adding charge and Gauss-Bonnet
terms. We find that the viscosity bound violation is not changed by the charge.
However, we find that two effects together create another instability for large
momentum regime. We argue the presence of tachyonic modes and show it
numerically. The stability of the black brane requires the Gauss-Bonnet
coupling constant $\lambda$($=2\alpha'/l^2$) to be smaller than 1/24. We draw a
phase diagram relevant to the instability in charge-coupling space.

18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
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The categories of this paper are: eess
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol