Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Superconducting instability in the surface of a topological insulator   It is argued that a superconducting instability appears in the electronic
states on the surface of a topological insulator due purely to electromagnetic
interactions. The discussion of this instability is based on the analysis of
the effective Coulomb interaction and the assumption that the system behaves
like a two dimensional Fermi liquid. It is shown that this superconducting
instability appears in the p-wave channel (like in the pure QED$_{3}$ case) and
an expression for the critical temperature of the transition is provided.

8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas