Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravitational Waves: the theorist's Swiss knife   Gravitational waves provide a novel and powerful way to test astrophysical
models of compact objects, early universe processes, beyond the Standard Model
particle physics, dark matter candidates, Einstein's theory of General
Relativity and extended gravity models, and even quantum gravity candidate
theories. A short introduction to the gravitational-wave background and the
method we are using to detect it will be presented. Constraints on various
astrophysical/cosmological models from the non-detectability of the
gravitational-wave background will be discussed. Gravitational waves from
transients will be highlighted and their physical implications will be
summarised.

25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom