Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Inclusive production of hadrons in $\ell^\uparrow p^\uparrow \to
  h^\uparrow X$ and spin measurements   We discuss the production of polarized hadrons in polarized lepton nucleon
interactions and show that the helicity density matrix of the hadron, when
measurable, can give information on the spin structure of the nucleon and the
spin dependence of the quark fragmentation process. Single spin asymmetries in
the $\ell N^\uparrow \to hX$ process are also briefly discussed.

9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th