Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: From AdS/CFT correspondence to hydrodynamics. II. Sound waves   As a non-trivial check of the non-supersymmetric gauge/gravity duality, we
use a near-extremal black brane background to compute the retarded Green's
functions of the stress-energy tensor in N=4 super-Yang-Mills (SYM) theory at
finite temperature. For the long-distance, low-frequency modes of the diagonal
components of the stress-energy tensor, hydrodynamics predicts the existence of
a pole in the correlators corresponding to propagation of sound waves in the
N=4 SYM plasma. The retarded Green's functions obtained from gravity do indeed
exhibit this pole, with the correct values for the sound speed and the rate of
attenuation.

22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
4
The categories of this paper are: cond-mat