Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A simple diagnosis of non-smoothness of black hole horizon: Curvature
  singularity at horizons in extremal Kaluza-Klein black holes   We propose a simple method to prove non-smoothness of a black hole horizon.
The existence of a $C^1$ extension across the horizon implies that there is no
$C^{N + 2}$ extension across the horizon if some components of $N$-th covariant
derivative of Riemann tensor diverge at the horizon in the coordinates of the
$C^1$ extension. In particular, the divergence of a component of the Riemann
tensor at the horizon directly indicates the presence of a curvature
singularity. By using this method, we can confirm the existence of a curvature
singularity for several cases where the scalar invariants constructed from the
Riemann tensor, e.g., the Ricci scalar and the Kretschmann invariant, take
finite values at the horizon. As a concrete example of the application, we show
that the Kaluza-Klein black holes constructed by Myers have a curvature
singularity at the horizon if the spacetime dimension is higher than five.

17
The categories of this paper are: q-fin
13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat