Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exact Black String Solutions in Three Dimensions   A family of exact conformal field theories is constructed which describe
charged black strings in three dimensions. Unlike previous charged black hole
or extended black hole solutions in string theory, the low energy spacetime
metric has a regular inner horizon (in addition to the event horizon) and a
timelike singularity. As the charge to mass ratio approaches unity, the event
horizon remains but the singularity disappears.

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The categories of this paper are: physics
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
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The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
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The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ