Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nucleon longitudinal spin structure at COMPASS   The nucleon spin structure is studied at COMPASS via the measurement of the
spin dependent properties of deep inelastic muon-deuteron scattering. Both
inclusive and semi-inclusive observables are investigated, with the emphasis
put on the latter. This allows to access, in particular, the gluon polarization
($\Delta G/G$) and the flavor decomposition of the quark helicity
distributions. Results from measurements with longitudinal target polarization
are presented, as well as uncertainties expected from the first 3 years of data
taking.

24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
19
The categories of this paper are: eess
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con