Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Scaling and asymptotic behavior of the $\gamma^* p$ total cross section
  at low x   The scaling in $\sigma_{\gamma^*p}$ cross sections (for $Q^2/W^2 << 1$) in
terms of the scaling variable $\eta = (Q^2 + m^2_0)/\Lambda^2 (W^2)$ is
interpreted in the generalized vector dominance/color-dipole picture (GVD/CDP).
The quantity $\Lambda^2 (W^2)$ is identified as the average gluon transverse
momentum absorbed by the $q \bar q$ state, $<\vec l^{~2}> = (1/6) \Lambda^2
(W^2)$. At any $Q^2$, for $W^2 \to \infty$, the cross sections for virtual and
real photons become universal, $\sigma_{\gamma^*p}(W^2,Q^2)/\sigma_{\gamma
p}(W^2) \to 1$. The gluon density corresponding to the color-dipole cross
section in the appropriate limit is found to be consistent with the results
from QCD fits.

23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga