Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Perpendicular Diffusion of Energetic Particles: A Complete Analytical
  Theory   Over the past two decades scientists have achieved a significant improvement
of our understanding of the transport of energetic particles across a mean
magnetic field. Due to test-particle simulations as well as powerful non-linear
analytical tools our understanding of this type of transport is almost
complete. However, previously developed non-linear analytical theories do not
always agree perfectly with simulations. Therefore, a correction factor $a^2$
was incorporated into such theories with the aim to balance out inaccuracies.
In this paper a new analytical theory for perpendicular transport is presented.
This theory contains the previously developed unified non-linear transport
theory, the most advanced theory to date, in the limit of small Kubo number
turbulence. For two-dimensional turbulence new results are obtained. In this
case the new theory describes perpendicular diffusion as a process which is
sub-diffusive while particles follow magnetic field lines. Diffusion is
restored as soon as the turbulence transverse complexity becomes important. For
long parallel mean free paths one finds that the perpendicular diffusion
coefficient is a reduced field line random walk limit. For short parallel mean
free paths, on the other hand, one gets a hybrid diffusion coefficient which is
a mixture of collisionless Rechester & Rosenbluth and fluid limits. Overall the
new analytical theory developed in the current paper is in agreement with
heuristic arguments. Furthermore, the new theory agrees almost perfectly with
previously performed test-particle simulations without the need of the
aforementioned correction factor $a^2$ or any other free parameter.

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The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci