Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: $J/\psi$ Production in Polarized and Unpolarized $ep$ Collision and
  Sivers and $\cos2\phi$ Asymmetries   We calculate the Sivers and $\cos2\phi$ azimuthal asymmetries in $J/\psi$
production in polarized and unpolarized semi-inclusive $ep$ collision
respectively, using the formalism based on transverse momentum dependent parton
distributions (TMDs). Non-relativistic QCD based color octet model is employed
for calculating the $J/\psi$ production rate. The Sivers asymmetry in this
process directly probes the gluon Sivers function. The estimated Sivers
asymmetry at $z=1$ is negative which is in good agreement with COMPASS data. We
also investigate the effect of TMD evolution on the Sivers asymmetry. The
$\cos2\phi$ asymmetry is sizable and probes the linearly polarized gluon
distribution in an unpolarized proton.

2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph