Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of Events with an Energetic Forward Neutron in Deep
  Inelastic Scattering at HERA   In deep inelastic neutral current scattering of positrons and protons at the
center of mass energy of 300 GeV, we observe, with the ZEUS detector, events
with a high energy neutron produced at very small scattering angles with
respect to the proton direction. The events constitute a fixed fraction of the
deep inelastic, neutral current event sample independent of Bjorken $x$ and
$Q^2$ in the range $ 3 \cdot 10^{-4} < \xbj < 6\cdot 10^{-3}$ and $10 < Q^2
<100$~GeV$^2$.

12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con