Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Collective motion of self-propelled particles interacting without
  cohesion   We present a comprehensive study of Vicsek-style self-propelled particle
models in two and three space dimensions. The onset of collective motion in
such stochastic models with only local alignment interactions is studied in
detail and shown to be discontinuous (first-order like). The properties of the
ordered, collectively moving phase are investigated. In a large domain of
parameter space including the transition region, well-defined high-density and
high-order propagating solitary structures are shown to dominate the dynamics.
Far enough from the transition region, on the other hand, these objects are not
present. A statistically-homogeneous ordered phase is then observed, which is
characterized by anomalously-strong density fluctuations, superdiffusion, and
strong intermittency.

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The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs