Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Black Hole Spin Constraints on the Mass Spectrum and Number of
  Axion-like Fields   Astrophysical observations of spinning BHs, which span $ 5M_\odot\lesssim
M_{\rm BH}\lesssim 5\times 10^8 M_\odot$, can be used to exclude the existence
of certain massive bosons via the superradiance phenomenon. In this work, we
explore for the first time how these measurements can be used to constrain
properties of statistical distributions for the masses of multiple bosonic
fields. Quite generally, our methodology excludes $N_{\rm ax}\gtrsim 30$ scalar
fields with a range of mass distribution widths and central values spanning
many orders of magnitude. We demonstrate this for the specific example of
axions in string theory and M-theory, where the mass distributions in certain
cases take universal forms. We place upper bounds on $N_{\rm ax}$ for certain
scenarios of interest realised approximately as mass distributions in M-theory,
including the QCD axion, grand unified theories, and fuzzy dark matter.

31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom