Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Surprising mappings of 2D polar active fluids to 2D soap and 1D
  sandblasting   Active fluids and growing interfaces are two well-studied but very different
non-equilibrium systems. Each exhibits non-equilibrium behavior quite different
from that of their equilibrium counterparts. Here we demonstrate a surprising
connection between these two: the ordered phase of incompressible polar active
fluids in two spatial dimensions without momentum conservation, and growing
one-dimensional interfaces (that is, the 1+1-dimensional Kardar-Parisi-Zhang
equation), in fact belong to the same universality class. This universality
class also includes two equilibrium systems : two-dimensional smectic liquid
crystals, and a peculiar kind of constrained two-dimensional ferromagnet. We
use these connections to show that two-dimensional incompressible flocks are
robust against fluctuations, and exhibit universal long-ranged, anisotropic
spatio-temporal correlations of those fluctuations. We also thereby determine
the exact values of the anisotropy exponent $\zeta$ and the roughness exponents
$\chi_{_{x,y}}$ that characterize these correlations.

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The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
16
The categories of this paper are: stat
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
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The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn