Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Non perturbative spherical gravitational waves   It is well-known that there is no spherical/topologically spherical
gravitational waves in vacuum space in general relativity. We show that a
deviation from general relativity leads to exact vacuum spherical gravitational
waves, no matter how tiny this deviation is. We also discuss the related
topics, including Vaidya-like metric in $f(R)$ gravity. We demonstrate that the
existence of spherical gravitational wave is a non perturbative property for
gravities. We investigate energy carried by this nonperturbative wave. We first
find the wave solution from investigations of Vaidya-like metric in $f(R)$
gravity, which has only one longitude polarization. We further extend it to a
metric with two transverse polarizations by directly solving the field
equation.

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The categories of this paper are: physics
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
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The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
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The categories of this paper are: econ
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
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The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom