Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Towards a Direct Measurement of the Quark Orbital Angular Momentum
  Distribution   We discuss two different definitions of partonic orbital angular momentum
given in the literature in terms of the Fourier transform of a Wigner
distribution, $F_{14}$, and a twist three generalized parton distribution,
$\tilde{E}_{2T}$, respectively. We derive a relation between the two
definitions which reflects their specific spin and intrinsic transverse
momentum/transverse space correlations as well as their gauge link structure.

12
The categories of this paper are: nucl-th
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The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
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The categories of this paper are: math-ph
18
The categories of this paper are: econ
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The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat