Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pion Properties in a Hot $\Pi N \Delta$ Gas   Based on a recent meson-exchange model for the vacuum $\pi\pi$ interaction we
compute selfconsistently the in-medium $\pi\pi$ scattering amplitude and pion
selfenergy in a hot $\pi N\Delta$ gas. The contributions to the pion selfenergy
are calculated from the $\pi\pi$ T-matrix as well as from p-wave interaction
with nucleons and thermally abundant $\Delta$'s. Results are presented for two
scenarios believed to be realized in the relativistic heavy ion collisions
performed at the GSI-SIS and the CERN-SpS. Possible implications for the
observed soft pion enhancement at both SIS and SpS are indicated.

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The categories of this paper are: astro-ph
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The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-lat
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The categories of this paper are: acc-phys
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The categories of this paper are: nlin
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The categories of this paper are: q-fin
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The categories of this paper are: physics
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an