Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Direct Determination of the Gluon Density in the Proton at Low x   A leading order determination of the gluon density in the proton has been
performed in the fractional momentum range $1.9 \cdot 10^{-3} < x_{g/p} < 0.18$
by measuring multi-jet events from boson-gluon fusion in deep-inelastic
scattering with the H1 detector at the electron-proton collider HERA. This
direct determination of the gluon density was performed in a kinematic region
previously not accessible. The data show a considerable increase of the gluon
density with decreasing fractional momenta of the gluons.

14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat