Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravitational Wave and CMB Probes of Axion Kination   Rotations of an axion field in field space provide a natural origin for an
era of kination domination, where the energy density is dominated by the
kinetic term of the axion field, preceded by an early era of matter domination.
Remarkably, no entropy is produced at the end of matter domination and hence
these eras of matter and kination domination may occur even after Big Bang
Nucleosynthesis. We derive constraints on these eras from both the cosmic
microwave background and Big Bang Nucleosynthesis. We investigate how this
cosmological scenario affects the spectrum of possible primordial gravitational
waves and find that the spectrum features a triangular peak. We discuss how
future observations of gravitational waves can probe the viable parameter
space, including regions that produce axion dark matter by the kinetic
misalignment mechanism or the baryon asymmetry by axiogenesis. For QCD axion
dark matter produced by the kinetic misalignment mechanism, a modification to
the inflationary gravitational wave spectrum occurs above 0.01 Hz and, for high
values of the energy scale of inflation, the prospects for discovery are good.
We briefly comment on implications for structure formation of the universe.

18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
1
The categories of this paper are: cs
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom