Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurement of charged pions in 12C + 12C collisions at 1A GeV and 2A
  GeV with HADES   We present the results of a study of charged pion production in 12C + 12C
collisions at incident beam energies of 1A GeV and 2A GeV using the HADES
spectrometer at GSI. The main emphasis of the HADES program is on the
dielectron signal from the early phase of the collision. Here, however, we
discuss the data with respect to the emission of charged hadrons, specifically
the production of pi+- mesons, which are related to neutral pions representing
a dominant contribution to the dielectron yield. We have performed the first
large-angular range measurement of the distribution of pi+- mesons for the 12C
+ 12C collision system covering a fairly large rapidity interval. The pion
yields, transverse-mass and angular distributions are compared with
calculations done within a transport model, as well as with existing data from
other experiments. The anisotropy of pion production is systematically
analyzed.

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The categories of this paper are: econ
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The categories of this paper are: solv-int
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The categories of this paper are: adap-org
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The categories of this paper are: cond-mat
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The categories of this paper are: cs
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The categories of this paper are: hep-th
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The categories of this paper are: funct-an
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The categories of this paper are: ao-sci
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The categories of this paper are: math
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The categories of this paper are: nucl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: alg-geom
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The categories of this paper are: stat
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The categories of this paper are: chem-ph
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The categories of this paper are: q-fin
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The categories of this paper are: comp-gas