Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Holography and hydrodynamics: diffusion on stretched horizons   We show that long-time, long-distance fluctuations of plane-symmetric
horizons exhibit universal hydrodynamic behavior. By considering classical
fluctuations around black-brane backgrounds, we find both diffusive and shear
modes. The diffusion constant and the shear viscosity are given by simple
formulas, in terms of metric components. For a given metric, the answers can be
interpreted as corresponding kinetic coefficients in the holographically dual
theory. For the near-extremal Dp, M2 and M5 branes, the computed kinetic
coefficients coincide with the results of independent AdS/CFT calculations. In
all the examples, the ratio of shear viscosity to entropy density is equal to
\hbar/(4\pi k_B), suggesting a special meaning of this value.

2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol