Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On energy-momentum and spin/helicity of quark and gluon fields   In special relativity, quantum matter can be classified according to
mass-energy and spin. The corresponding field-theoretical notions are the
energy-momentum-stress tensor T and the spin angular momentum tensor S. Since
each object in physics carries energy and, if fermionic, also spin, the notions
of T and S can be spotted in all domains of physics. We discuss the T and S
currents in Special Relativity (SR), in General Relativity (GR), and in the
Einstein-Cartan theory of gravity (EC). We collect our results in 4 theses: (i)
The quark energy-momentum and the quark spin are described correctly by the
canonical (Noether) currents T and S, respectively. (ii) The gluon
energy-momentum current is described correctly by the (symmetric and gauge
invariant) Minkowski type current. Its (Lorentz) spin current vanishes, S = 0.
However, it carries helicity of plus or minus one. (iii) GR contradicts thesis
(i), but is compatible with thesis (ii). (iv) Within the viable EC-theory, our
theses (i) and (ii) are fulfilled and, thus, we favor this gravitational
theory.

18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph