Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Origin of Transverse Flow at the SPS   We study the transverse expansion in central Pb+Pb collisions at the CERN
SPS. Strong collective motion of hadrons can be created. This flow is mainly
due to meson baryon rescattering. It allows to study the angular distribution
of intermediate mass meson baryon interactions.

3
The categories of this paper are: physics
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
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The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math