Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Diffractive Vector Meson Production at HERA: from Soft to Hard QCD   Experimental results from HERA on diffractive vector meson production and
their theoretical interpretation within microscopic QCD are reviewed with an
emphasis on the BFKL color dipole and kt-factorization approaches.

19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn