Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Soft transverse expansion in Pb(158 AGeV) on Pb collisions:
  preequilibrium motion or 1st order phase transition?   Transverse expansion of centrally produced matter in Pb on Pb collisions at
beam energies around 158 AGeV appears to be rather `soft'. Two possible reasons
-- an extended preequilibrium stage and a first order phase transition from a
quark-gluon-plasma into hadronic matter -- are discussed. The softening of
transverse expansion caused by preequilibrium dynamics is estimated with the
aid of the transport model RQMD which does not contain a first order phase
transition. It is found that the anisotropy of transverse flow in non-central
reactions is very different in the preequilibrium and hydrodynamic scenarios
even if the latter are based on a strong 1st order transition.

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The categories of this paper are: math
0
The categories of this paper are: hep-ph
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
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The categories of this paper are: nlin
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The categories of this paper are: astro-ph