Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Constraints on the Geometries of Black Holes in Classical and
  Semiclassical Gravity   Constraints on the geometries of static spherically symmetric black holes are
obtained by requiring that the spacetime curvature be analytic at the event
horizon. Further constraints are obtained by requiring that the semiclassical
trace equation be satisfied in the case that only conformally invariant fields
are present. It is found that there exists a range of sizes for which zero
temperature black holes do not exist. The range depends on the number and types
of quantized fields present.

14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
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The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th