Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dipole-proton $S$-matrix derived from diffractive meson
  electroproduction   Through a determination of the $S$-matrix element for the scattering of a
localized colour dipole on a proton, we show that saturation effects can
already be sizable at HERA. The saturation scale is found to be around 1-1.5
$GeV^2$ for the highest available energies and for central collisions, and is a
decreasing function of the impact parameter.

16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics