Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Surface charge of a flat superconducting slab in the Meissner state   The electrostatic potential in the flat superconducting slab is evaluated in
the framework of the Ginzburg-Landau theory extended by Bardeen to low
temperatures. For magnetic fields below B_c1, we discuss the formation of a
surface charge induced by the Bernoulli potential of the suppercurrents.

8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn