Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Suppression of back-to-back hadron pairs at forward rapidity in d+Au
  Collisions at sqrt(s_NN)=200 GeV   Back-to-back hadron pair yields in d+Au and p+p collisions at sqrt(s_NN)=200
GeV were measured with the PHENIX detector at the Relativistic Heavy Ion
Collider. Rapidity separated hadron pairs were detected with the trigger hadron
at pseudorapidity |eta|<0.35 and the associated hadron at forward rapidity
(deuteron direction, 3.0<eta<3.8). Pairs were also detected with both hadrons
measured at forward rapidity; in this case the yield of back-to-back hadron
pairs in d+Au collisions with small impact parameters is observed to be
suppressed by a factor of 10 relative to p+p collisions. The kinematics of
these pairs is expected to probe partons in the Au nucleus with low fraction x
of the nucleon momenta, where the gluon densities rise sharply. The observed
suppression as a function of nuclear thickness, p_T, and eta points to cold
nuclear matter effects arising at high parton densities.

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The categories of this paper are: alg-geom
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The categories of this paper are: hep-lat
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: stat
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The categories of this paper are: mtrl-th
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The categories of this paper are: eess