Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Calculation of gluon contribution to the proton spin by using the
  non-perturbative quantization \`a la Heisenberg   The contribution of crossed gluon fields in flux tubes connecting quarks to
the proton spin is calculated. The calculations are performed following
non-perturbative Heisenberg's quantization technique. In our approach a proton
is considered as consisting of three quarks connected by three flux tubes. The
flux tubes contain color longitudinal electric and transversal electric and
magnetic fields. The transversal fields causes the appearance of the angular
momentum density. The dimensionless relation between the angular momentum and
the mass of the gluon fields is obtained. The contribution to proton spin from
rotating quarks and flux tubes connecting quarks is estimated. Simple numerical
relation between the proton mass, the speed of light and the proton radius,
which is of the same order as the Planck constant, is discussed.

24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex