Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Transverse spin observables in hard-scattering hadronic processes within
  collinear factorization   We review what is currently known about the transverse spin structure of
hadrons, in particular from observables that can be analyzed within a collinear
framework. These effects have been around for 40 years and represent a critical
test of perturbative QCD. We look at both proton-proton and lepton-nucleon
collisions for various final states. While the main focus is on transverse
single-spin asymmetries, we also discuss how longitudinal-transverse
double-spin asymmetries offer a complimentary, yet equally important, source of
information on the quark-gluon content of hadrons. We also summarize some
recent progress in solidifying the theoretical formalism behind these
observables and give an outlook on future directions of research.

27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat
24
The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat