Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Associated $J/\psi + \gamma$ production as a probe of the polarized
  gluon distribution   Associated production of $J/\psi$ and a $\gamma$ has recently been proposed
as clean probe of the gluon distribution. The same mechanism can be used to
probe the polarized gluon content of the proton in polarized proton-proton
collisions. We study $J/\psi + \gamma$ production at both polarized fixed
target and polarized collider energies.

13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th