Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electromagnetic fields in Schwarzschild and Reissner-Nordstr\"om
  geometry. Quantum corrections to the black hole entropy   Using standard coordinates, the Maxwell equations in the Reissner-Nordstr\"om
geometry are written in terms of a couple of scalar fields satisfying
Klein-Gordon like equations. The density of states is derived in the
semi-classical approximation and the first quantum corrections to the black
hole entropy is computed by using the brick-wall model.

9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
19
The categories of this paper are: eess
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs