Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First measurement of transverse-spin-dependent azimuthal asymmetries in
  the Drell-Yan process   The first measurement of transverse-spin-dependent azimuthal asymmetries in
the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190
GeV/$c$, $\pi^{-}$ beam and a transversely polarized ammonia target. Three
azimuthal asymmetries giving access to different transverse-momentum-dependent
(TMD) parton distribution functions (PDFs) are extracted using dimuon events
with invariant mass between 4.3 GeV/$c^2$ and 8.5 GeV/$c^2$. The observed sign
of the Sivers asymmetry is found to be consistent with the fundamental
prediction of Quantum Chromodynamics (QCD) that the Sivers TMD PDFs extracted
from DY have a sign opposite to the one extracted from semi-inclusive
deep-inelastic scattering (SIDIS) data. We present two other asymmetries
originating from the pion Boer-Mulders TMD PDFs convoluted with either the
nucleon transversity or pretzelosity TMD PDFs. These DY results are obtained at
a hard scale comparable to that of a recent COMPASS SIDIS measurement and hence
allow unique tests of fundamental QCD universality predictions.

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The categories of this paper are: q-alg
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The categories of this paper are: alg-geom
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The categories of this paper are: q-fin
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The categories of this paper are: solv-int
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The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
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The categories of this paper are: cmp-lg
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-ex
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The categories of this paper are: quant-ph
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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: stat
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The categories of this paper are: hep-th
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The categories of this paper are: econ
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The categories of this paper are: eess