Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurement of Sivers Asymmetries for Di-jets in \sqrt{s}=200 GeV pp
  Collisions at STAR   Measurement of the transverse spin dependence of the di-jet opening angle in
pp collisions at sqrt{s}=200 GeV has been performed by the STAR collaboration.
An analyzing power consistent with zero has been observed over a broad range in
pseudorapidity sum of the two jets with respect to the polarized beam
direction. A non-zero (Sivers) correlation between transverse momentum
direction of partons in the initial state and transverse spin orientation of
the parent proton has been previously observed in semi-inclusive deep inelastic
scattering (SIDIS).
  The present measurements are much smaller than deduced from predictions made
for STAR di-jets based on non-zero quark Sivers functions deduced from SIDIS,
and furthermore indicate that gluon Sivers asymmetries are comparably small.

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The categories of this paper are: quant-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: math-ph
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The categories of this paper are: q-bio
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The categories of this paper are: hep-lat
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The categories of this paper are: gr-qc
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The categories of this paper are: cond-mat
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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: ao-sci
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The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: chem-ph
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The categories of this paper are: cs