Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Towards an explanation of transverse single-spin asymmetries in
  proton-proton collisions: the role of fragmentation in collinear
  factorization   We study the transverse single-spin asymmetry for single-hadron production in
proton-proton collisions within the framework of collinear twist-3
factorization in Quantum Chromodynamics. By taking into account the
contribution due to parton fragmentation we obtain a very good description of
all high transverse-momentum data for neutral and charged pion production from
the Relativistic Heavy Ion Collider. Our study may provide the crucial step
towards a final solution to the longstanding problem of what causes transverse
single-spin asymmetries in hadronic collisions within Quantum Chromodynamics.
We show for the first time that it is possible to simultaneously describe
spin/azimuthal asymmetries in proton-proton collisions, semi-inclusive
deep-inelastic scattering, and electron-positron annihilation by using
collinear twist-3 factorization in the first process along with transverse
momentum dependent functions extracted from the latter two reactions.

24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
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The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex