Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Investigation into the limits of perturbation theory at low Q^2 using
  HERA deep inelastic scattering data   A phenomenological study of the final combined HERA data on inclusive deep
inelastic scattering (DIS) has been performed. The data are presented and
investigated for a kinematic range extending from values of the four-momentum
transfer, $Q^2$, above 10$^4$ GeV$^2$ down to the lowest values observable at
HERA of $Q^2$ = 0.045 GeV$^2$ and Bjorken $x$, $x_{\rm Bj}$ = 6 $\cdot$
10$^{-7}$. The data are well described by fits based on perturbative quantum
chromodynamics (QCD) using collinear factorisation and evolution of the parton
densities encompassed in the DGLAP formalism from the highest $Q^2$ down to
$Q^2$ of a few GeV$^2$. The Regge formalism can describe the data up to $Q^2
\approx$ 0.65 GeV$^2$. The complete data set can be described by a new fit
using the ALLM parameterisation. The region between the Regge and the
perturbative QCD regimes is of particular interest.

2
The categories of this paper are: math
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
18
The categories of this paper are: econ
19
The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol