Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermal Freeze-out and Longitudinally Non-uniform Collective Expansion
  Flow in Relativistic Heavy Ion Collisions   The non-uniform longitudinal flow model (NUFM) propsed recently is extended
to include also transverse flow. The resulting longitudinally non-uniform
collective expansion model (NUCEM) is applied to the calculation of rapidity
distribution of kaons, lambdas and protons in relativistic heavy ion collisions
at CERN-SPS energies. The model results are compared with the 200 A GeV/$c$ S-S
and 158 A GeV/$c$ Pb-Pb collision data. The central dips observed in
experiments are reproduced in a natural way.

37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat