Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nuclear transparency effect of $\pi^{-}$-mesons in p+$^{12}$C- and
  d+$^{12}$C- interactions at 4.2A GeV/c   The use of nuclear transparency effect of \pi^{-}-mesons in proton, and
deuteron induced interactions with carbon nuclei at 4.2A GeV/c, to get
information about the properties of nuclear matter, is presented in this work.
Half angle (\theta_{1/2}) technique is used to extract information on nuclear
transparency effect. The \theta_{1/2} divides the multiplicity of charged
particles into two equal parts depending on their polar angle in the lab. frame
in pp interactions. Particles with angle smaller than (incone particles) and
greater than (outcone particles) \theta_{1/2} are considered separate. The
average values of multiplicity, momentum and transverse momentum of the
\pi^{-}-mesons are analyzed as a function of a number of identified protons in
an event. We observed evidences in the data which could be considered as
transparency effect. For quantitative analysis, the results are compared with
cascade model. The observed effects are categorized into leading effect
transparency and medium effect transparency. The transparency in the latter
case could be the reason of collective interactions of grouped nucleons with
the incident particles.

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The categories of this paper are: eess
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The categories of this paper are: physics
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The categories of this paper are: atom-ph
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The categories of this paper are: adap-org
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
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The categories of this paper are: hep-th
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The categories of this paper are: supr-con
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The categories of this paper are: chao-dyn
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The categories of this paper are: bayes-an
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The categories of this paper are: math-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: nlin
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The categories of this paper are: astro-ph