Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An analysis of polarized parton distribution functions with nonlinear
  QCD evolution equations   We present the polarized parton distribution functions from a QCD analysis of
the worldwide polarized deep inelastic scattering data, based on the dynamical
parton distribution model. All the sea quarks and gluons are dynamically
generated from QCD radiations, with the nonperturbative input contains only the
polarized valence quark distributions. This approach leads to a simple
parametrization, which has only four free parameters. In the analysis, we apply
the DGLAP equations with parton-parton recombination corrections. The
parameterized nonperturbative input at an extremely low $Q_0^2$ reproduces well
the spin-dependent structure functions measured at high $Q^{2}$. Comparisons
with experimental observations and some other polarized parton distribution
functions are also shown. Our results are in good agreement with the
experimental data and consistent with some other parameterized models.
Furthermore, our analysis gives the positive polarized gluon distribution and
it suggests that the gluon distribution plays an important role to the proton
spin content. The polarized antiquark distributions are non-zero at high $Q^2$
but quite small compared to polarized valence quark distribution, based on this
dynamical parton model analysis. This analysis shows smaller statistical
uncertainties for the polarized sea quark and gluon distributions, thanks to
the fewer free parameters used for the parametrization of the initial polarized
PDFs.

7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
4
The categories of this paper are: cond-mat
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys