Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Minimal Stochastic Model for Fermi's Acceleration   We introduce a simple stochastic system able to generate anomalous diffusion
both for position and velocity. The model represents a viable description of
the Fermi's acceleration mechanism and it is amenable to analytical treatment
through a linear Boltzmann equation. The asymptotic probability distribution
functions (PDF) for velocity and position are explicitly derived. The diffusion
process is highly non-Gaussian and the time growth of moments is characterized
by only two exponents $\nu_x$ and $\nu_v$. The diffusion process is anomalous
(non Gaussian) but with a defined scaling properties i.e. $P(|{\bf x}|,t) =
1/t^{\nu_x}F_x(|{\bf x}|/t^{\nu_x})$ and similarly for velocity.

29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
3
The categories of this paper are: physics