Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Random walk in a two-dimensional self-affine random potential :
  properties of the anomalous diffusion phase at small external force   We consider the random walk of a particle in a two-dimensional self-affine
random potential of Hurst exponent $H=1/2$ in the presence of an external force
$F$. We present numerical results on the statistics of first-passage times that
satisfy closed backward master equations. We find that there exists a
zero-velocity phase in a finite region of the external force $0<F<F_c$, where
the dynamics follows the anomalous diffusion law $ x(t) \sim \xi(F) \
t^{\mu(F)} $. The anomalous exponent $0<\mu(F)<1$ and the correlation length
$\xi(F)$ vary continuously with $F$. In the limit of vanishing force $F \to 0$,
we measure the following power-laws : the anomalous exponent vanishes as
$\mu(F) \propto F^a$ with $a \simeq 0.6$ (instead of $a=1$ in dimension $d=1$),
and the correlation length diverges as $\xi(F) \propto F^{-\nu}$ with $\nu
\simeq 1.29$ (instead of $\nu=2$ in dimension $d=1$). Our main conclusion is
thus that the dynamics renormalizes onto an effective directed trap model,
where the traps are characterized by a typical length $\xi(F)$ along the
direction of the force, and by a typical barrier $1/\mu(F)$. The fact that
these traps are 'smaller' in linear size and in depth than in dimension $d=1$,
means that the particle uses the transverse direction to find lower barriers.

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The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys