Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theoretical estimate on tensor-polarization asymmetry in proton-deuteron
  Drell-Yan process   Tensor-polarized parton distribution functions are new quantities in spin-one
hadrons such as the deuteron, and they could probe new quark-gluon dynamics in
hadron and nuclear physics. In charged-lepton deep inelastic scattering (DIS),
they are studied by the twist-two structure functions $b_1$ and $b_2$. The
HERMES collaboration found unexpectedly large $b_1$ values than a naive
theoretical expectation based on the standard deuteron model. The situation
should be significantly improved in the near future by an approved experiment
to measure $b_1$ at JLab (Thomas Jefferson National Accelerator Facility).
There is also an interesting indication in the HERMES result that finite
antiquark tensor polarization exists. It could play an important role in
solving a mechanism on tensor structure in the quark-gluon level. The
tensor-polarized antiquark distributions are not easily determined from the
charged-lepton DIS; however, they can be measured in a proton-deuteron
Drell-Yan process with a tensor-polarized deuteron target. In this article, we
estimate the tensor-polarization asymmetry for a possible Fermilab
Main-Injector experiment by using optimum tensor-polarized PDFs to explain the
HERMES measurement. We find that the asymmetry is typically a few percent. If
it is measured, it could probe new hadron physics, and such studies could
create an interesting field of high-energy spin physics. In addition, we find
that a significant tensor-polarized gluon distribution should exist due to
$Q^2$ evolution, even if it were zero at a low $Q^2$ scale. The
tensor-polarized gluon distribution has never been observed, so that it is an
interesting future project.

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The categories of this paper are: astro-ph
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The categories of this paper are: q-alg
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The categories of this paper are: stat
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The categories of this paper are: solv-int
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The categories of this paper are: funct-an
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The categories of this paper are: math-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: acc-phys
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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: econ
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The categories of this paper are: bayes-an
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The categories of this paper are: gr-qc
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-th