Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Leading and higher twists in the proton polarized structure function at
  large Bjorken x   A phenomenological parameterization of the proton polarized structure
function has been developed for x > 0.02 using deep inelastic data up to ~ 50
(GeV/c)**2 as well as available experimental results on both photo- and
electro-production of proton resonances. According to the new parameterization
the generalized Drell-Hearn-Gerasimov sum rule is predicted to have a
zero-crossing point at Q**2 = 0.16 +/- 0.04 (GeV/c)**2. Then, low-order
polarized Nachtmann moments have been estimated and their Q**2-behavior has
been investigated in terms of leading and higher twists for Q**2 > 1
(GeV/c)**2. The leading twist has been treated at NLO in the strong coupling
constant and the effects of higher orders of the perturbative series have been
estimated using soft-gluon resummation techniques. In case of the first moment
higher-twist effects are found to be quite small for Q**2 > 1 (GeV/c)**2, and
the singlet axial charge has been determined to be a0[10 (GeV/c)**2] = 0.16 +/-
0.09. In case of higher order moments, which are sensitive to the large-x
region, higher-twist effects are significantly reduced by the introduction of
soft gluon contributions, but they are still relevant at Q**2 ~ few (GeV/c)**2
at variance with the case of the unpolarized transverse structure function of
the proton. Our finding suggests that spin-dependent correlations among partons
may have more impact than spin-independent ones. As a byproduct, it is also
shown that the Bloom-Gilman local duality is strongly violated in the region of
polarized electroproduction of the Delta(1232) resonance.

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The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: stat
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The categories of this paper are: comp-gas
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The categories of this paper are: cond-mat
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The categories of this paper are: eess
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The categories of this paper are: q-bio
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The categories of this paper are: alg-geom
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The categories of this paper are: ao-sci
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: chem-ph