Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Probing axial quark generalized parton distributions through exclusive
  photoproduction of a $\gamma\,\pi^\pm$ pair with a large invariant mass   Exclusive photoproduction of a $\gamma\,\pi^\pm$ pair in the kinematics where
the pair has a large invariant mass and the final nucleon has a small
transverse momentum is described in the collinear factorization framework. The
scattering amplitude is calculated at leading order in $\alpha_s$ and the
differential cross sections for the process are estimated in the kinematics of
the JLab~12-GeV experiments. The order of magnitude of the predicted
cross-sections seems sufficient for a dedicated experiment to be performed. The
process turns out to be very sensitive to the axial generalized parton
distribution combination $\tilde{H}_u - \tilde{H}_d$.

16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
24
The categories of this paper are: dg-ga